
Qass. 
Book 



COPYRIGHT DEPOSIT 



I 



CHEMISTRY: 

GENERAL, MEDICAL, AND PHARMACEUTICAL, 



INCLUDING 



THE CHEMISTRY OF THE U. S. PHARMACOP(EIAo 



A MANUAL 

ON THE SCIENCE OF ^H^MT«TRY, AND ITS APPLICA= 
TIONS IN MEDICINE AND PHARMACY. 



BY 
JOHN ATTFIELD, F.R.S., 

M. A. AND PH. D. (TUBINGEN), F. I, C, F. C. S. 

PROFESSOR OF PRACTICAL CHEMISTRY TO THE PHARMACEUTICAL SOCIETY OF GREAT 

BRITAIN, 1862-96 ; FORMERLY DEMONSTRATOR OF CHEMISTRY AT ST BARTHOLOMEW'S 

HOSPITAL, LONDON; HONORARY MEMBER OF TWENTY-THREE SOCIETIES, 

ASSOCIATIONS, AND COLLEGES OF PHARMACY IN EUROPE AND AMERICA ; 

ONE OF THE THREE EDITORS OF THE BRITISH PHARMACOPOEIA, 1885 ; 

EDITOR OF THE ADDENDUM TO THE BRITISH PHARMACOPCEIA, 

EDITOR OF THE BRITISH PHARMACOPCEIA, 1898, AND 

OF ITS INDIAN AND COLONIAL ADDENDUM, 1900 

Edited by LEONAKD DOBBIN 

PH. D. (WtJRZBURG), F, I. C, F. C. S. 

LECTURER ON CHEMISTRY IN THE UNIVERSITY OF EDINBURGH ; LATELY 

EXAMINER IN CHEMISTRY ON THE BOARD OF EXAMINERS FOR SCOTLAND, 

OF THE PHARMACEUTICAL SOCIETY OF GREAT BRITAIN 



NINETEENTH EDITION 




LEA BROTHERS & CO., 
PHILADELPHIA AND NEW YORK, 

19 6. 



— ! 



cPtT 



UBRARY of CONGRESS 

Iwocouici Kecelved 

SEP 'Z^ 1906 

CL 

COPY A, 



)LASe C^ AAC. No. 



Copyright, 1906, by 
LEA BROTHERS & CO. 



Authority to use for comment the Pharmacopoeia of the United 
States bf America (Eighth Decennial Revision), in this volume, has 
been granted by the Board of Trustees of the United States Pharmaco- 
pceial Convention ; which Board of Trustees is in no way responsible 
for the accuracy of any translations of the Official Weights and 
Measures, or for any statement as to strength of Official Preparations. 



DORNAN, PRINTER, 
PHILADELPHIA. 



"But the greatest error of all is, mistaking the ultimate 
end of knowledge ; for some men covet knowledge out of a 
natural curiosity and inquisitive temper; some to entertain 
the mind with variety and delight ; some for ornament and 
reputation ; some for victory and contention ; many for lucrp 
and a livelihood; and but few for employing the diviae 
gift of reason to the use and benefit of mankind."— Lord 
Bacon, 



"I hold that the greatest friend to man is labor; that 
knowledge without toil, if possible, were worthless ; that 
toil in pursuit of knowledge is the best knowledge we can 
attain ; that the continuous effort for fame is nobler than 
fame itself; that it is not wealth suddenly acquired which 
is deserving of homage, but the virtues which a man exer- 
cises in the slow pursuit of wealth— the abilities so called 
forth, the self-denials so imposed ; in a word, that Labor 
and Patience are the true schoolmasters on earth."— Lord 
Lytton. 



" I want to learn all that one human being can. It is 
awful to be buried alive in the coffin of one's own ignorance 
and helplessness."— Graham Travers. 



PEEFAOE, 



The short title on the back of a book, and even the words on 
the title-page, are generally, and even necessarily, imperfect 
descriptions of the contents, and hence not unfrequently induce 
at the outset misconceptions in the minds of readers. The 
author of Chemistry : General^ Medical, and Pliarrtiaceuticalj 
would at once state, therefore, that his chief aim is to teach 
the science of chemistry to medical and pharmaceutical 
pupils. So far as laws and principles are concerned, the book 
is a work on General Chemistry ; but inasmuch as those laws 
and principles are elucidated and illustrated by that large por- 
tion of chemistry which is directly interesting to medical prac- 
titioners and pharmacists, the book may be said to be a work 
on Medical Chemistry and on Pharmaceutical Chemistry. Only 
in this conventional sense would the author speak of Medical 
and Pharmaceutical Chemistry ; for the truths of chemistry 
are the same far all students — crystalline verities which cannot 
be expanded or compressed to suit any class of workers. The 
leading principles of the science, however, can as easily be 
illustrated by or deduced from those facts which have interest 
as from those which have little or no special interest for the 
followers of medicine and pharmacy. The grand and simple 
leading truths or laws of chemistry, the lesser truths or prin- 
ciples, and nearly all the interesting relationships of elements 
and compounds — in a word, the science of chemistry — can be 
taught to medical and pharmaceutical students with little other 
aid than that afforded by the materials which lie in rich abun- 
dance all around these workers. Such a mode of teaching the 
general principles of the science and their applications in medi- 
cine and pharmacy is adopted in this volume. It is a mode which 
greatly increases the usefulness of the science to the students 



viii PREFACE. 

chiefly addressed, while it in no way diminishes the value of 
chemistry to them as an instrument of mental culture — an 
instrument which sharpens and expands the powers of observa- 
tion, which enlarges and strengthens memory and imagina- 
tion, which gives point to the perceptive faculties, and which 
develops and elaborates the powers of thought and of reason. 

This Manual is intended, then, as a systematic exponent of 
the science of chemistry, but is written mainly for the pupils, 
assistants, and principals engaged in medicine and pharmacy. 
It is a Manual of Applied Chemistry or Technical Chemistry, 
but it is first of all a Manual of Chemistry. 

The book will be found equally useful as a reading-book for 
students having no opportunities of attending lectures or per- 
forming experiments, or, on the other hand, as a text-book for 
college pupils ; while its comprehensive Index, containing 
nearly ten thousand references, will fit the work for after- 
consultation in the course of business or professional practice. 

From most other chemical text-books it difi<ers in three par- 
ticulars : first, in the exclusion of matter relating to compounds 
which at present are only of interest to the scientific chemist ; 
whose aims have no special relation to medicine and pharmacy ; 
secondly, in containing more or less of the chemistry of every 
substance recognized officially or in general practice as a 
remedial agent ; thirdly, in the paragraphs being so cast that 
the volume may be used as a guide in studying the science 
experimentally. 

The order of subjects is that which, in the author's opinion, 
best meets the requirements of medical and pharmaceutical 
students in Great Britain, Ireland, India, the British colonies, 
and the United States of America. Introductory pages are 
devoted to a few leading properties of the elements. A 
review of the facts thus unfolded afi'ords opportunity for stat- 
ing the views of philosophers respecting the manner in which 
these elements influence each other as components of terres- 
trial matter. The consideration in detail of the relations of 
the elementary and compound radicals follows, synthetical and 
analytical bearings being pointed out, and attention frequently 



PREFACE. IX 

directed to connecting or underlying truths or general prin- 
ciples. The chemistry of substances met with in vegetables 
and animals, or of similar substances artificially produced (the 
so-called " organic chemistry "), is next considered. Chemical 
toxicology and the chemical as well as microscopical characters 
of morbid urine, urinary sediments, and calculi are then given. 
The concluding sections form a laboratory -guide to beginners 
in the study of quantitative analysis. 

In the course of the treatment outlined in the preceding 
paragraph it will be observed that the whole of the elements 
are first noticed very shortly, to give the pupil a general view 
of his course of study, and afterward at length and thor- 
oughly ; that the chemistry of the metallic radicals precedes 
that of the acid radicals (a term applied consistently through- 
out the Manual to designate that part of each of the acids 
which is not replaceable hydrogen) ; and that while the 
metallic radicals are arranged according to their analytical 
relations, the common radicals are arranged according to 
exchangeable value or quantivalence, and the rarer acid 
radicals alphabetically. By this plan the more important 
facts and principles are repeatedly brought under consideration, 
the points of view, however, differing according as interest is 
concentrated on physical, synthetical, analytical, or quantitative 
properties. This arrangement of matter was adopted, also, partly 
in the belief that the separate and general truths of chemistry 
never do or can enter the mind in the order of any scientific classi- 
fication at present possible. Chemical facts are not yet united 
by any single, consistent theory. In the current state of 
chemical knowledge consistency in the methodical arrangement 
even of elements can only be carried out in one direction, and 
is necessarily accompanied by inconsistencies in other directions 
— a result most perplexing to learners, and hence totally sub- 
versive of the chief advantages of classification. For this reason 
the writer has preferred to lead up to, rather than follow, scien- 
tific classification — has allowed analogies and affinities to 
suggest, rather than be suggested by, classification. Among the 
acidulous radicals, especially, any known system of classification 



X PREFACE. 

would have given undue prominence to one set of relations, 
and undeserved obscurity to others. Then, by separating 
more important from less important matter, instruction is 
adapted to the wants of gentlemen whose opportunities of 
studying chemistry vary greatly, and are unavoidably insuf- 
ficient to enable them to gain a knowledge of the whole area 
of the science. One great advantage of the mode of treat- 
ment is, that difficulties of nomenclature, notation, chemical 
constitution, and even those arising from conventionality of 
language, are explained as they arise, instead of being massed 
under the head of " Introductory Chapters," " Preliminary 
Considerations," or " General Remarks," which are not unfre- 
quently too difficult to be understood by a beginner, too vo- 
luminous to be remembered except by the aid of subsequent 
lessons, and are consequently the cause of much trouble and 
confusion. This plan has also admitted of greater prom- 
inence being given to "The General Principles of Chemical 
Philosophy," the only section to which the student is asked 
fre(|uently to return until he finds himself naturally employing 
those principles in the interpretation of the phenomena obtained 
by experiment. 

The metric system of weights and measures (that which, 
doubtless, is destined to supersede all others) is alone used 
in the sections on quantitative analysis. In other parts of 
the Manual avoirdupois weights and imperial measures are 
employed, necessarily. 

It is hoped that the numerous etymological references scat- 
tered throughout the following pages will be found useful. 
AYords in Greek continue to be rendered, b}' special request, 
in English characters, letter for letter. The word •' official " 
is used throughout for things recognized officially by the com- 
pilers of pharmacopoeias. 

Chemical substances recognized in the United States Phar- 
macopoeia, but not in the British Pharmacopoeia, have, never- 
theless, a certain amount of notice in the British editions of 
the ^lanual, and the chemical substances official in Great 
Britain are noticed in the x\nierican editions. 



PREFACE. XI 

Students are strongly recommended to test their progress by 
frequent examination. To this end appropriate questions are 
appended to each subject. 

The author's ideal of a manual of chemistry for medical* and 
pharmaceutical students is, then, one in which not only the 
science of chemistry is taught, but in which the chemistry 
of every substance having interest for the followers of med- 
icine and pharmacy is noticed at more or less length in pro- 
portion to its importance, and at least its position in relation 
to the leading principles of chemistry is set forth with all 
attainable exactness. The extent to which he has realized 
this ideal he leaves to others to decide. Such a work will 
doubtless in certain parts partake of the character of a diction- 
ary ; but this is by no means a fault, especially if a good index 
be appended, for the poifits of contact between pure and applied 
chemistry are thus multiplied, and abundant outlets supplied by 
which a lover of the science may pass into other chemical domains 
by aid of other guides, or even into the regions of original re- 
search. Among the rarer alkaloids, bitter bodies, glucosides, salts 
of organic radicals, solid fats, fixed oils, volatile oils, resins, oleo- 
resins, gum-resins, balsams, and coloring-matters mentioned in 
this volume, will be found many such points whence the ardent 
student may start for the well-known, the less-known, or the 
untrodden paths of scientific chemistry. 

Watford, Herts, England, 
September, 1906. 



LIST OF PREVIOUS EDITIONS. 



No. OF 

Edition 



4 


1872 


5 


1873 


6 


1875 



7 


1876 


8 


1879 


9 


1881 


10 


1883 


n 


1885 


12 


1889 


13 


1889 


14 


1898 


15 


1893 


16 


1898 


17 


1898 


18 


1903 



Date. Notes. 

1 1867 A liand-book of practical chemistry only. 

2 1869 This and succeeding editions included the 

chemistry of the British Pharmacopceia. 

3 1870 American edition ; adapted to the United 

States Pharmacopoeia. 
English edition. 
American edition. . 
English edition. This and succeeding editions 

contained notices of substances included in 

the Indian Pharmacopceia. 
American edition. 



English editions. 

American edition. 
English edition. 
American edition. 
English edition. 
American edition. 
English edition. 
American edition. 



English editions. 



ADVICE TO STUDENTS 
RESPECTING THEIR OBJECT IN STUDYING. 



Avoid studying chemistry, or indeed any subject, merely by 
way of " preparation for examination ;" all ordinary " exam- 
inations " being, admittedly, inefficient tests of competency. 
Do not so mistake the means for the ejid. You are studying 
to fit yourself for your position in the world. Work dili- 
gently, study thoughtfully and deliberately ; above all, be 
thorough, otherwise your knowledge will be inaccurate and 
transient, and will be unaccompanied by that enlightenment 
of the understanding, that mental training, mental discipline, 
and general elevation of the intellect, which constitute, in a 
word, education. When you are thus educated you will with 
ease and pleasure pass any examination in the knowledge you 
have thus acquired. 

All authorities on education, whether statesmen, teachers, 
or examiners, regard " examinations," even by the most highly 
skilled " Board," with ample time at its disposal and a wide 
area from which to select questions, as but a partial test of 
knowledge and an imperfect test of education. It is the least 
unsatisfactory, however, that has been devised, and is especially 
useful when, following instead of leading education, it is re- 
stricted to the subjects of a well-defined, earnestly followed, 
compulsory public curriculum of study — a curriculum directed 
by a competent representative body, administered by properly 
qualified teachers, and followed by pupils who have had sound 
preliminary training. 

Students ! in all honor and in the highest self-interest take 
care that any inefficiencies inseparable from '■ examination " are 
abundantly compensated by the extent and precision of your 
knowledge and by the soundness and thoroughness of your 
whole education. 



APPARATUS. 

List of Apparatus for Experiments in Analysis. 
List of apparatus suitable for tlie three months' course of practi- 
cal chemistry in the summer session of medical schools or for any 
similar series of lessons — including the preparation of elementary 
gases, analytical reactions of common metals and acidulous radicals, 
analysis of single salts, chemical toxicology, and the examination 
of urine, urinary sediments, and calculi : 



One dozen test-tubes. 

Test-tube stand. 

Test-tube cleaning-brush. 

A few pieces of glass tubing, 
eight to sixteen inches long, 
with a few inches of india-rub- 
ber tubing to fit. 

Small flask. 

Two small beakers. 

Two small funnels. 

Two watch-glasses. 

Two or three glass rods. 

Wash-bottle. 

Small pestle and mortar. 

A 2-pint earthenware basin. 



A 2-inch and a 3-inch evaporat- 

ing-basin. 
Two porcelain crucibles. 
Blowpipe. 
Crucible tongs. 
Round file. 
Triangular file. 
Small retort-stand. 
Sand-tray. 
Wire triangles. 
Platinum wire and foil. 
Test-papers. 
Filter-paper. 
Towel. 
Two dozen corks. 



{This set, packed in a case, can be obtained of any chemical-appara- 
tus maker for about seven dollars.) 

List of Apparatus for Experiments in Synthesis and Analysis. 
A larger set, suitable for the performance of most of the synthet- 
ical as well as qualitative analytical experiments described in this 
Manual : 



A set of evaporating-basins, of the 

following sizes : 

One 3-inch; one 4-inch; one6i- 
inch ; one 7i-inch ; one 8|-inch. 
One retort-stand and three rings. 
Two test-glasses. 
One half-pint flask. 
Half a quire of filter-paper. 
Two porcelain crucibles. 
One measure-glass, 5 oz. 
Blowpipe, 8-inch. 
Two glass funnels. 
One dozen test-tubes (hard glass). 
One test-tube brush. 
One pair of 8-inch brass crucible 

tongs. 

{This set, packed in a case, can be obtained of any chemical-appara- 
tus maker for about twelve dollars.) 

A sponge, towels, and a note-book may be included, 
xiv 



Two soup-plates. 

One flat-plate. 

Two spatula knives. 

One pair of scissors. 

One round file. 

One triangular file. 

Half a pound of glass rod. 

Half a pound of glass tubing. 

One foot of small india-rubber 

tubing. 
Three dozen corks of various 

sizes. 
Platinum wire and foil. 
Test-papers. 

A nest of three beakers. 
One test-tube stand. 



APFABATUS. 



XV 



List of Furniture of a Chemical Laboratory. 

The following apparatus should be ready to hand for students fol- 
lowing an extended course of practical chemistry, in a room set 
apart for the purpose : 

Test-tube rack, two dozen holes. 

Iron stand or cylinder for support- 
ing large dishes. 

Iron adapters for fitting dishes to 
cylinder. 

Pestle and mortar, 5 or 6 inches. 

One 6-inch funnel. 

Brown pan, 1- or 2-gallon. 

White jug, 1-gallon. 

Water-bottle, quart. 

Twenty-eight test-bottles, 6-oz. 



A bench or table and stool. 
Water-supply and waste-pipe. 
A cupboard attached to a chimney 

with an outward draught. 
A furnace fed with coke ; tongs, 

hot-plate or sand-bath, etc. 
A waste-box. 
Shelves for chemical and other 

materials in jars or bottles. 
Gas-supply and lamp with flexible 

tube (or a spirit-lamp and 

spirit). 

Other articles, such as flasks, retorts, receivers, condensers, large 
evaporating-dishes, may be obtained as wanted. In Quantitative 
Analysis the apparatus described in the sections on that subject will 
be required. 



List of Fluid Reagents. 

Certain chemical substances are used so frequently in analytical 
processes that it is desirable to have small quantities placed in bot- 
tles in front of the operator. (Seep. 22.) As these reagents are 
generally employed in a state of solution, nearly all the solid salts 
may at once be dissolved (in distilled water). The bottles employed 
should be well stoppered, and of 5 or 6 ounces capacity. Common 
glass bottles of this size may be had for about one dollar and a 
quarter per dozen. The bottles should not be more than about 
three-fourths full •, single drops, if required, can then be poured out 
with ease and precision. The following list of test-solutions is 
recommended ; directions for methods of preparing the substances 
not readily purchasable will be found by referring to the Index : 



Sulphuric Acid, Cone, and dilute. 
Nitric Acid, " " 

Hydrochloric Acid " " 

Acetic Acid, dilute. 



Potassium Hydroxide, 5 percent. 
Sodium, 5 to 15 percent. 
Hydroxide Ammonia, 10 percent. 
Lime-water, saturated. 



The next nine may contain about 10 percent, of sohd salt 



Ammonium Carbonate, with a 
little solution of Ammonia 
added. 

Ammonium Chloride. 

Ammonium Phosphate. 



Ammonium Hydrosulpliide. 
Barium Chloride. 
Calcium Chloride. 
Potassium Chromate. 
Sodium Bitartrate. 



XVI 



SOLID CHEMICAL SUBSTASCES 



The succeeding seven may have a strength of about 5 percent. 



Potassium Ferrocyanide. 
Potassium Ferricyanide. 
Potassium Iodide. 
Ammonium Oxalate. 



Ferric Chloride. 
Silver Nitrate. 
Chloroplatinic Acid. 



Lists of Solid Chemical Substances for Study. 

List of chemical substances necessary for the practical study of the 
non-metallic elements mentioned on pp. 1 7 to 37. The quantities are 
sufficient for several experiments : 

Potassium Chlorate . . . I oz. ] Phosphorus ^ oz. 

Black Mansranese Oxide . 1 oz. Hvdrochloric Acid ... 1 oz. 



1 oz. 

2 oz. 



Sulphur 2^ oz. 

iodine i oz. 



Zinc . . . . . . . 

Sulphuric Acid . . • 

List of chemical substances necessary for the analytical study of 
the important metallic and acidulous radicals (pp. 71 to 361). The 
quantities will depend on the frequency with 'which experiments are 
repeated or analyses performed ; those mentioned are sufficient for 
one or two students. The eight substances mentioned in the above 
list are included : 

Black Manganese Oxide - j lb. 
Manganese Chloride . . . t oz. 
Cobalt Chloride .... 50 grs. 

Nickel Nitrate ? oz. 

Chromic Chloride ... \ oz. 

Gold-leaves 2 or 3. 

Cadmium Chloride . . \ oz. 
Bismuth Nitrate .... i oz. 
Potassium Bromide . . t oz. 

Starch 1 oz. 

Potassium Nitrate ... 1 oz. 
Copper borings or turnings 1 oz. 

Indigo 1 oz. 

Potassium Chlorate ... 1 oz. 

Iodine ^ oz. 

Alcohol (90 to 95 percent.) ] oz. 

Sulphur . . 1 oz. 

Potassium Acid Oxalate . 1 oz. 

Citric Acid ] oz. 

Phosphorus 1 oz. 

Borax 1 oz. 

Turmeric j oz. 

Benzoic Acid 50 grs. 

Fluor Spar ...... 1 oz. 

Tannic Acid . . . . 50 grs. 

(rallic Acid 50 grs. 

Pyrogallic Acid , . > 50 grs. 



The set of test-solutions described 


in the previous section : 




Potassium Carbonate . 


1 oz. 


Tartaric Acid .... 


1 oz. 1 


Litmus 


\ oz. i 


Magnesium Sulphate . . 


1 oz. 1 


Zinc Sulphate .... 


1 oz. i 


Alum 


1 oz. 


Ferrous Sulphide . . 


1 lb. 


Oak-cralls 


] oz. 


Potassium Thiocvanate . 


\ oz. 


Arsenic Trioxide . . 


h oz. 


Zinc 


* lb. 
^ lb. 


Charcoal ...... 


Ferrous Sulphate . . 


1 oz. 


Copper-foil 


. 1 oz. 


Copper Sulphate . . . 


1 oz. 


Tartarated Antimony . 


. \ oz. 


Mercury 


. 1 oz. 


Mercuric Chloride . 


. ^ oz. 


Calomel . 


. h oz. 


Tin 


. 1 oz. 


Potassium Bicarbonate 


. 1 oz. 


Lead Acetarc .... 


. 1 oz. 


Potassium Cvanide 


. ^ oz. 


Sodium Thiosulphate . 


. 1 oz. 


A Lithium Salt .... 


10 grs. 


Strontium Nitrate . . 


. ]- oz. 



CHEMICALS. 



xvii 



The quantities of materials required for the study of chemistry 
sjjntheticallij will necessarily vary with the desires and tastes of the 
operator or according to the number and requirements of students 
working together, 

The jiiaterials that will be needed for the home-study of organic 
chemistry will vary with the requirements of the student. By the 
time he has qualified himself for a preliminary experimental course 
in that section of the science he may trust largely to his own judg- 
ment as regards both materials and apparatus. 



CONTRACTIONS USED IN THIS MANUAL. 



B. P., British Pharmacopoeia. 

U. S. P., United States Pharma- 
copoeia. 

C, Centigrade. 

Co., Cubic centimetres. 



F., Fahrenheit. 

grm., Gramme. 

mm., Millimetre. 

T. S., Test solution, U. S. P. 

Y. S., Volumetric solution, U. S.P. 



CONTENTS. 



Preface ^ vii 

Advice to Students « . . . xiii 

Lists of Apparatus xiv 

List of Furniture of a Chemical Laboratory . . xv 

List of Fluid Reagents xv 

Lists of Solid Chemical Substances for Study . . xvi 

Introduction ... . 17 

General Properties of the Non-Metallic Elements . 20 

Derivation of Names of Elements 37 

Numerical and Physical Matters 40 

The General Principles of Chemical Philosophy . 49 
The Metallic Elements, their Official Prepara- 
tions AND Tests : 
Salts of Potassium, Sodium, Ammonium, Lithium, 
Barium, Strontium, Calcium, Magnesium, Zinc, 
Manganese, Cobalt, Nickel, Aluminium, Iron, 
Chromium, Arsenic, Antimony, Tin, Gold, Platinum, 
Copper, Mercury, Lead, Bismuth, Cadmium, Silver . 71 

Analytical Tables for the Metals 243 

Common Acid Radicals, Official Acids, and Tests : 
Chlorides, Bromides, Iodides, Cyanides, Nitrates, Hypo- 
chlorites, Chlorates, Bromates, lodates, Acetates, 
Sulphides, Sulphites, Sulphates, Thiosulphates, Persul- 
phates. Carbonates, Oxalates, Tartrates, Citrates, Phos- 
phates, Borates, 251 

Salts of Rarer Acid Radicals : 

Benzoates, Cyanates, Formates, Hippurates, Ferrocy- 
anides, Ferricyanides, Fluorides, Hypophosphites, 
Lactates, Malates, Meconates, Metai)hosphates, Ni- 
trites, Phosphites, Pyrophos})hates, Silicates, Tannates 
and Gallates, Thiocyanates, Urates, Valerates, etc. .821 

xi.K 



XX C02^TENTS. 

PAGE 

Analytical Table for Acid Radicals 404 

Systematic Analysis 354 aiul 556 

Organic Chemistry 368 

Chemical Toxicology 559 

Examination of Urine and Calculi 572 

Official Galenical Preparations 592 

Official Chemical Preparations 592 

Quantitative Measurements 593 

Quantitative Analysis : 

Introductory Remarks 609 

Volumetric Analysis .... 611 

Gravimetric Analysis 638 

Dialysis 680 

Appendix : 

The Elements, their Symbols, and Atomic 

Weights 682 

Index 685 



CHEMISTRY: 

GENERAL, MEDICAL, AND PHARMACEUTICAL. 



INTRODUCTION.^ 

Man can neither create matter nor destroy matter, but he 
can permanently alter its character. All that is burned is 
thus altered, and nearly all that is eaten and digested is 
thus altered. Man can in many cases bring about, or in a 
measure control, these permanent alterations which matter is 
capable of undergoing ; and in all cases he can investigate the 
alterations in matter which are ever proceeding around him 
in animal, vegetable, and mineral nature. The study of 
these alterations in all their known length, and breadth, and 
depth, is the study of natural science, of which Chemistry^ 
the study of most of the alterations — is one of the most com- 
prehensive branches. 

The infinite varieties of solid, liquid, and gaseous matter 
of which our earth and atmosphere are composed may be so 
altered by man as to be resolved into a few distinct substan- 
ces appropriately termed Elements (^Elementiim, first or con- 
stituent principle of anything), for by no known means can 
they be further decomposed. More than seventy of these 
elements have been proved to exist. Some, such as gold, occur 
naturally in the uncombined state ; but the greater number 
are combined in so subtle a manner as to conceal them from 
ordinary methods of observation. Thus none of the common 
properties of water indicate that it is composed of two ele- 
ments, both gases, but differing much from each other ; nor 
can the senses of sight, touch, and taste, or other ordinary 
means of examination, detect in their concealment the three 
elements of which sugar is composed. The art by which 

^ Students using this book as a guide in following clicmistry practi- 
cally should read the first four i>ages, and then commence work by pre- 
paring oxygen. All students should read the prefatory pages, especially 
the page of " Advice to Students." 

2 17 



18 INTRODVCTION. 

these and all other compound substances are resolved into 
their elements is termed the art of Chemistry, a name derived 
possibly from the Arabic word kamai, to conceal.' The art 
of Chemistry also includes the construction of compounds 
from elements, the decomposition of compounds, and the con- 
version of substances of one character into others of different 
character. The science of Chemistry deals with the general 
principles or leading truths relating to the elements, and to 
the manner in which they severally combine ; with the obser- 
vation of the phenomena which accompany chemical combi- 
nations, interactions, and decompositions ; and with the de- 
scription of the general properties of the substances produced 
during these changes. 

From these few words concerning the nature of the art and 
science of chemistry, it will be seen that in most of the occu- 
pations that engage the attention of man, Chemistry plays an 
important part — in few more so than in the practice of the 
various departments of Medicine, especially the branches 
termed Therapeutics ^ and Pharmacy.^ 

Air, water, food, drugs, and chemical substances — in short, 
all material things — are composed, as stated, of Elements. 
An intimate knowledge of the properties of the more impor- 
tant Elements, both in the free (or uncombined) and in the 
combined state, and of the various substances they form when 
they have combined with each other ; all attainable knowledge 

^ The idea that common metals contained valuable metals concealed 
within them was the one seed from which chemical knowledge mainly 
sprang. The men who endeavored to find the secret of such conceal- 
ment were appropriately termed alchemists, and their efforts were spoken 
of as alchemy (al limia, from l-amai, to conceal). Their persistent labors, 
generation after generation, were unsucessful so far as the transmuta- 
tion of baser metals into gold was concerned, yet were invaluable to pos- 
terity ; for new substances were discovered and truths of nature unveiled : 
from these discoveries further discoveries resulted, and thus grew the 
still ])rogressing branch of knowledge called Chemistry. 

'^ Therapeutics (OepanevTiKo^, therapentil'os, from Bepairevu), therapeud, I 
nurse, serve, or cure) is the branch of medicine which treats of the ap- 
plication of remedies for diseases. The therapeutist also takes cogni- 
zance of hygiene — the department of medicine which respects the preser- 
vation of health — and of dietetics, the subject of diet or food. By phar- 
macology is understood the normal or physiological action of drugs, as 
underlying the therapeutic action. 

' Pharmacy (from 4,dpixaicop. jjharmakon a drug) is the generic name for 
the operations of preparing or compounding medicines, whether per- 
formed by the Medical Practitioner or by the Pharmaceutical Chemist or 
the Chemist and Druggist. It is also sometimes applied, like the corres- 
ponding term Surgery, to the apartment in whicli the operations are con- 
ducted. Pharmacognosy is the study of the crude drugs of the vegetable 
and animal kingdoms. 



METALLIC ELEMENTS. 19 

of the power or force (the chemical force or chemical affinity) 
by which the elements contained in the compounds are held 
together ; and the application of such knowledge to Pharmacy 
and Medicine, must be the objects sought to be attained by 
the student of chemistry for whom especially this book has been 
written. 



The Elements. — -Of the seventy or so known elements, the 
study of about forty is essential for the proper comprehension 
of chemistry. Fortunately for medical and pharmaceutical 
students all these are of special medical or pharmaceutical 
interest, hence such students while learning the science itself 
can study its applications to medicine and pharmacy. Two- 
thirds of the forty are metals, one-third non-metals. The re- 
mainder of the elements ^ are seldom met with in Nature, or 
occur only in small quantities ; and a number of them have 
not received any practical application either in Medicine, Art, 
or Manufacture. 

Before intimately studying the elements, it is desirable to 
acquire some general notions concerning them : such a proced- 
ure will also serve to introduce the practical student to his 
apparatus, and make him better acquainted with the various 
methods of manipulation.^ 

Metallic Elements. — With regard to the metallic elements, 
it may safely be assumed that the reader has sufficient knowl- 
edge for present purposes ; but little, therefore, need be said 
respecting them at this stage. He has an idea of the appear- 
ance, relative weight, hardness, etc., of such metallic ele- 
ments as gold, silver, copper, lead, tin, zinc, and iron. If he 
has not a similar knowledge of mercury, antimony, arsenic, 
platinum, nickel, aluminium, magnesium, potassium, and 
sodium, he should embrace the earliest opportunity of seeing 
and examining specimens of each of these metallic elements. 

^ A list will be found in the Appendix. {See also pp. 37 and 59.) 
'^ This allusion to apparatus need not discourage the youngest student 
of chemistry who is at the same time a pupil in medicine or phar- 
macy. With the aid of a few phials, wine-glasses, or other similar 
vessels always at hand, he may, by studying the following pages, learn 
the chemical reactions which are constantly occurring in the course of 
making up medicines, understand the processes by which medicinal 
preparations are manufactured, and detect adulterations, imjiuritievS. or 
faults of manufacture. Among the substances used iu medicine will be 
found nearly all the chemical materials required. If, in addition, a 
dozen test-tubes and a few feet of glass tubing be procured, many of 
the experiments described may be formed. For full lists of apparatus 
and chemical materials, see the prefatory pages. 



20 SOX-METALLIC ELEMESTS. 

Non-Metallic Elements. — With regard to the non-metallic 
elements, it is here supposed that the student has no general 
knowledge. He should commence his studies, therefore, by 
a series of operations as follows, on eighj of their number. 

OXYGEN. 

Frepnraf ion.— Oxygen is the most abundant element in nature, 
forming (in a stateof combination) about one-half of the whole 
weight of our globe. To obtain it for experimental purposes 
all that is necessary is \o apply heat to certain easily decompos- 
able compounds containing oxygen, whereupon the latter is 
evolved in the gaseous condition. There are several substances 
which readily }ield oxygen upon heating, but the crystalline salt 
known as potassium chlorate is perhaps best fitted for the experi- 
ment. The size and form of the vessel in which to heat the salt 
will mainly depend on the quantity of oxygen required; but for the 
purposes of the student the best is a f&sf-fube, an instrument in 
constant use in studying practical chemistry. It is simply a tube 
of thin glass, a few inches in length, and half or three-quarters of 
an inch in diameter, closed by fusion at one end. It is made 
of thin glass, in order that it may be rapidly heated or cooled 
without risk of fi-acture. {See pictures of test-tubes in Figs. 3 
and 4.) 

Outline of the Process. — Heat potassium chlorate, Potami 
ehloras, U. S. P., (say, as much as will lie on a twenty-five 
cent piece in a test-tube held in the flame of a Bunsen burner 
or spirit lamp. The salt first fuses — i.e., liquefies — and forms 
a colorless liquid; and on further heating this liquid, gaseous 
oxygen is quickly evolved. Before applying heat, however, 
provision should be made for collecting the gas. 

Collection of Gases {See in Fig. 3 ). — Procure a piece of glass 
tubing about the thickness of a qtiill pen, and a foot or eigh- 
teen inches long, and fit it to the test-tube by means of a 
cork. (Longer tubes may be neatly cut to any size by 
smartly drawing the edge of a triangular file across the glass 
at the required point, then clasping the tube, the scratch be- 
ing between the hands, and pulling the portions asunder, the 
pull being exert'ed as if to open out the crack which the file 
has commenced.) The tube is fixed in the cork through a 
round hole made by the aid of a red-hot wire, or, better, by 
a rat-tail file, or, best of all, by one of a set of cork-borers — 
pieces of lirass tubing of different diameters, sharpened at 
one end and havins: a flat head at the other. The cork and 



OXYGEN. 



21 



test-tube must be fitted to each other accurately and closely, 
but not so tightly as to break the test-tube. The long piece 
of tubing should be bent to the most convenient shape for de- 
livering the gas. 

To Bend Glass Tubes. — Hold the part of the tube required 
to be bent in any gas- or spirit-flame (a fish-tale gas-jet, for 
example. Fig. 1), constantly rotating it, so that about an inch 

Fig. 1. 




Softening and bending glass tubes. 



Fig. 2. 



of the glass becomes heated. It will soon begin to soften, and 
by the gentle pressure of the fingers, it can then be made to 
assume any required angle. In the present case, the tube 
should be heated at about four inches from the extremity 
to which the cork is attached, and bent to an angle of 90 
degrees (Fig. 2). A similar bend may be made near the other 
end, and the short piece of straight tubing should then be 
cut ofl*. The cut ends should finally 
be rounded off" by holding them in 
the flame until the glass softens. The 
finished tube has the shape shown in 
Fig. 3. 

Fit the cork and bent tube into 
the test-tube ; the apparatus will then .i^ 
be ready for delivering gas at a con- 1^ 
venient distance from the heated por- " 
tion of the arrangement. To collect 
the oxygen, have ready three or four 
test-tubes (or small wide-mouthed bot- 
tles) quite filled with water, and in- 
verted in a basin or other vessel, also 
containing water, taking care to keep 
the mouths of the filled tubes a little 
below the surface. Now apply heat 
to the chlorate contained in the test- 
tube, and so arrange the open end of 

the bent tube under the water that the gas whicli presently 
escapes with effervescence from the melted cldorate mnv 




22 



NON-METALLIC ELEMENTS. 



pass out from the free end of the tube, and may bubble 
into and gradually fill the previously water-filled inverted 
test-tubes. The first tubeful may be rejected, as it probably 
consists of little more than the air which was originally in 





This picture represents the preparation, collection, and storage of small 
quantities of oxygon gas. A test-tube and bent glass tube, connected bv means 
of a perforated cork, are supported by the arm of an iron stand. (The"appara- 
tus might be held by two lingers.) The test-tube is heated ina "Bunsen" flame. 
The spirit-lamp show n at back might be used instead.) The gas evolved from 
the heated substance disj.laces water from an inverted test-tube. Spare tubes 
in a test-tul)e rack are at hand, and tubes alreadv filled with the gas have been 
set aside until wanted. A set of cork-borers, a round file, a triansularfile and 
a test-tube cleaning brush are lying on the table or students bench. Below 
are cupboards for apparatus, above are bottles containing testing liquids, etc. 



OXYGEN. 23 

the apparatus and has been displaced by the oxygen. That 
which comes afterwards will be practically pure oxygen. 

As each tube or bottle becomes full, close its mouth (still 
under the surface of the water) by a cork and then set it 
aside ; or instead of a cork a little cup (such as a porcelain, 
crucible or small gallipot) may be brought under its mouth, 
and the cup, with the mouth of the tube in it, be lifted out 
of the water and placed aside until wanted, the water remain- 
ing in the cup effectually preventing the gas from escaping. 

On the large scale, oxygen may be prepared in the same way, 
larger vessels (glass flasks or iron bottles) being employed. If 
the potassium chlorate be previously mixed with about an equal 
weight of common black manganese oxide, the oxygen will be 
given off at a considerably lower temperature. 

Oxygen, when required in a very pure state for medicinal pur- 
poses, might be prepared by adding water, in small successive 
quantities, to a mixture of sodium peroxide and sand ; but the 
high degree of purity attained in the commercial preparation of 
oxygen from the atmosphere (by a method that will be described 
later) by manufacturers who supply the gas compressed in steel 
cylinders, renders this oxygen suitable for all such purposes. 

Note on the Collection and Storage of Gases. — A number of 
gases, whether prepared for experimental purposes or on the large 
scale, may be collected and stored in vessels inverted in water in 
the manner just described for oxygen. The coal-gas (generated 
at gas-works by strongly heating coal in iron retorts, very much 
the shape of test-tubes, only as many feet long as a test tube is 
inches) is stored in the well-known iron gas-holders which may be 
regarded as playing the part of the inverted test-tubes or bottles in 
the oxygen experiment. It is plain that collection and storage 
over water is only practicable in the case of gases which do not 
dissolve to more than a small extent in water. Coal-gas and 
other gases besides oxygen may be stored in steel cylinders under 
high pressure. 

Solubility of Gases in Water. — All gases are more or less 
soluble in water. The quantity of any gas which dissolves de- 
pends upon the temperature — cold water dissolving more than 
hot — and upon the pressure. Whatever the quantity of a gas 
dissolved by a liquid at ordinary atmospheric pressure, double that 
quantity is dissolved at double the pressure, treble that quantity 
at treble pressure, and so on. This is a general law (Henry and 
Dalton) regarding the solubility of gases in liquids at constant 
temperatures. 

Properties. — Free oxygen is a colorless, odorless, and taste- 
less gas. Cailletet and Pictet succeeded in liquefying it on a 



24 NON-METALLIC ELEMENTS. 

small scale, and Wroblewski obtained it in larger quantity as 
a transparent fluid, closely resembling water in appearance, 
but slightly bluer ; Dewar has now liquefied it in large quan- 
tities, and has also obtained it in the solid condition. Obvi- 
ously oxygen is not very soluble in water, or it could not be 
collected by the aid of that liquid. It is soluble, however, to 
a certain extent, about 3 volumes dissolving in 100 of water 
at ordinary temperatures. When any ordinary sample of cis- 
tern or river water is heated, or subjected to greatly reduced 
pressure, numerous small bubbles of gas, containing a consid- 
erable proportion of oxygen, gradually escape from it. The 
presence of dissolved oxygen in river and sea water is essen- 
tial for the respiration of fishes. 

To observe the relation of oxygen to combustion, remove 
one of the tubes from the water, by placing the thumb over 
its mouth, and apply for a second a lighted wood match to the 
orifice ; the gas will be found to be incombustible. Extin- 
guish the flame of the match, and then quickly introduce the 
still incandescent carbonized extremity of the wood well in- 
side the test-tube ; the wood will at once burst into flame, 
owing to the extreme violence with which oxygen supports com- 
bustion. These tests of the presence of free oxygen may also be 
applied at the extremity of the delivery-tube whilst the gas is 
being evolved. (It is desirable to retain two tubes of the gas 
for use in subsequent experiments ; also one tube in which 
only one-third of the water has been displaced by oxygen.) 

Relation of Oxygen to Animal and Vegetable Life. — Not only 
the carbon at the end of a piece of charred wood, but any other 
substance that will burn in air (which, as will be seen presently, 
in diluted oxygen) will burn more brilliantly in pure oxygen. 
The warmth of the bodies of animals is kept up by the continuous 
burning of the tissues in the oxygen of the air, drawn into the 
system through the lungs. The product of this combustion is 
exhaled into the air as a gaseous compound of carbon and oxygen 
termed carbonic anhydride, a gas which, in sunlight, is absorbed 
by and decomposed in the cells of plants with fixation of carbon 
and liberation of the oxygen. Thus, too, is the atmosphere kept 
constant in composition. 

Memorandum. — At present it is not advisable that the reader 
should trouble himself with the consideration of the chemical 
action which occurs either in the elimination of oxygen from 
its compounds, or in the separation of any of the following non- 
metallic elements from their combinations. It is to the properties 
of these elements themselves, especially in their free, or uncom- 



HYDROGEN. 



25 



bined, condition, that he should at present restrict his attention. 
Working thus from simple to more complex facts, he will in due 
time find that the comprehension of such actions as occur in the 
preparation of these few elements will be easier than if he 
attempted their full study now. 



HYDROGEN. 

Preparation and Collection.— The element Hydrogen, in 
the uncombined state, is also a gas.^ It is obtainable from its 
commonest compound, water (of which about one-ninth by 
weight is hydrogen), by the agency of hot zinc or iron, but 
more conveniently by the action of either of these metals on 
cold dilute sulphuric acid. The apparatus used for making 
oxygen may be employed for this experiment; but no lamp 
is required. Place several pieces of thin zinc ^ in the gener- 
ating tube (Fig. 4), or in a common glass bottle (Fig. 5),. or 
flask, and cover them with water. The collecting-tubes 
(these also may be wide-mouthed bottles) being ready, add 
concentrated sulphuric acid (oil of vitrol) to the zinc and 
water, in the proportion of about 1 volume of acid to 5 of 
water, and fit on the delivery-tube ; or pour the acid down 

^ Graham obtained alloys of hydrogen with palladium and other metals 
compounds in which several hundred times its bulk of gas is retained 
by the metal iyi vacuo or even at a red heat. This was regarded as phys- 
ical confirmation of the opinion long held by chemists, that hydrogen is 
a gaseous metal. Graham termed it hydrogenmm, other chemists hydrium, 
and considered its relative weight in the solid state to be nearly three- 
fourths that of water. Olszewski claimed to have liquefied hydrogen in 
1895. It has been liquefied by Dewar, who finds its critical temperature 
(i. e., the temperature to which it must be cooled before it is possible to 
convert it into the liquid state by the application of any pressure, how- 
ever great) to be approximately— 233° C, and its boiling point— 243° C. 

Helium. — More than thirty years ago, Frankland and Lockyer, to ac- 
count for a certain yellow line in the solar spectrum, assumed the exist- 
ence of a separate element which they termed helium. In 1895 Ramsay 
found a new element in the mineral clevite giving an ignition a yellow 
line in the spectrum, probably identical with that just alluded to. To 
this new terrestrial element he gave the name helium. Ramsay, Collie, 
and Travers afterwards found helium in many minerals, often accom- 
panied by hydrogen, though it seems rather to have analogies with argon, 
another comparatively recently discovered element which will be re- 
ferred to under nitrogen. Many minerals yield gases when heated, and 
even contain gases in cavities. 

^ The best form is granulated zinc prepared by heating zinc in an iron 
ladle over a fire, and immediately the metal is fused, pouring it in a slow 
stream into a pail of water from a height of 8 or 10 feet. Each drop of 
zinc thus yields a thin little bell, which, for its weight, presents a largo 
surface to the action of the acid liquid. If the melted zinc becomes too 
hot, the little bells will not bo formed. A trace of iron in the zinc groally 
increases the rate at which the hydrogen is evolved. 



26 



NON-METALLIC ELEMENTS. 



such a fimnel-tiibe ' as is shown in Fig. 5 ; the hydrogen at 
once escapes with effervescence from the fluid. Having re- 
jected the first portions (or having waited until the air orig- 



FiG. 5. 




Preparation of hydrogen. 

inally in the bottle may be considered to be all expelled), 
collect four or five tubes of the gas in the manner described 
under oxygen. 

Notes. — In making larger quantities, bottles of appropriate size 
may be employed. Other metals, notably potassium and sodium, 
liberate hydrogen the moment they come into contact w4th water ; 
but the processes are not economical, and the action is danger- 
ously violent. 

Properties. — Hydrogen, like oxygen, is colorless, odorless, 
and tasteless. If iron be used to generate the gas, it has a 
marked smell ; but this is due to impurities derived from the 
iron. 

Apply a flame to the mouth of the delivery-tube, but not 
until it is plain that the brisk eflTervescence of hydrogen must 
have resulted in the driving out of all air from the generating 
tube or bottle, for the mixture of hydrogen and air may explode. 
Ignition of the hydrogen ensues, showing that, unlike oxygen, 
it is combustible. 

Plunge a lighted match well into a tube (or wide-mouthed 
bottle) containing free hydrogen; the gas is ignited, but the 
match becomes extinguished. This shows that hydrogen is 
not a supporter of ordinary combustion. 

1 Fnnnel-tnbes may be purchased of the apparatus-maker; or, if the 
pupil has access to a table blowpipe, and the advantage of a tutor to di- 
rect his operations, they may be made by himself. 



HYDROGEN, 27 

Hydrogen in burning unites with the oxygen of the air 
and forms water, w^hich may be condensed on a cool glass or 
other surface. Prove this by holding a glass vessel a few 
inches above a hydrogen-flame. In burning the hydrogen 
contained in one of the tubes or bottles, the flame is best seen 
when the tube is held mouth upward, and water poured in 
so as to expel the gas gradually. 

If, instead of this gradual combination of the two elements 
oxygen and hydrogen, they be mixed together in the right 
proportions and then ignited, they will rapidly combine, and 
explosion will result. Prepare a mixture of this kind by 
filling up with hydrogen a test-tube from which one-third of 
the water has already been expelled by oxygen. Remove 
the tube from the water, placing a finger over its mouth, and 
having a lighted match ready, apply the flame; explosion 
ensues, owing to the instantaneous combination of the whole 
bulk of the tw^o elements, and the expansive force of the 
highly heated steam produced. If anything larger than a 
test-tube is employed in this experiment, it should be an 
aerated water bottle, or some such vessel equally strong. 

Notes. — These gases thus unite at a temperature far higher than 
that of boiling water, two volumes of hydrogen and one of oxy- 
gen yielding two of gaseous water (steam). 

The noise of such explosions is caused by concussion between the 
suddenly expanded gaseous body and the air. 

The force of the explosion, or, in other words, the pressure of 
the suddenly heated and therefore suddenly expanded steam, is 
below that necessary to break the test-tube. Some pressure, 
however, is exerted; and hence the necessity of the precaution 
previously suggested, of allowing all the air Avhich may be in a 
hydrogen-apparatus to escape before proceeding with the experi- 
ments. If a flame be applied to the delivery-tube before all the 
air is expelled, the probable result will be ignition of the mixture 
of hydrogen and oxygen (of the air) and consequent explosion. 
But even in this case the generating vessel is not often fractured 
unless it be large and of thin glass, the ordinary effect being that 
the cork is blown out, and the delivery-tube broken on falling to 
the ground. 

Hydrogen is a constituent of all the substances burned for pro- 
ducing artificial light, such as solid fats, oil, and coal-gas. The 
explosive force of large quantities, such as a roomful, of coal-jras 
and air is well known to suffice for blowing out that side of" the 
room which offers least resistance. 

The composition of water can be proved analytically as well as 



I 



28 



NON-METALLIC ELEMENTS. 



synthetically, by passing a current of electricity through dilute 
sulphuric acid (electrolysis, from '>vo)^ luo, I loose, or I decom- 
pose). During the passage of the current, hydrogen and oxygen 
are liberated in the proportions in which they are present in 
water, twice as much hydrogen as oxygen, by volume, being 
produced. The quantity of sulphuric acid remains the same at 
the end as at the beginning of the experiment, the quantity of 
water having alone diminished. 

Combustion (from comburo, I burn). — The experiments with 
hydrogen and oxygen illustrate the true character of combustion. 
Whenever chemical combination is suflSciently intense to be ac- 
companied by heat and light, the materials are said to undergo 
combustion. Combustion only occurs at the line of contact 
of the combining bodies; a jet of oxygen will burn in an 
atmosphere of hydrogen quite as easily as a jet of hydrogen in 
oxygen. A jet of air (diluted oxygen) will burn as readily in a 
jar of coal-gas as a jet of coal-gas burns in air; each is combus- 
tible, each supports the combustion of the other. Hence the 
terms combustible and mpporter of combustion are merely conven- 
tional, and only applicable so long as the circumstances under 
which they are applied remain the same. In the case of sub- 
stances burning in air, the conditions are, practically, always 
the same; hence no confusion arises from regarding air as the 
great supporter of combustion, and bodies which burn in it as 
being combustible. 

Fig. 6. Fig. 7. 




Structure of candle-flame. 



"Bunsen," or air-gas, burner. 



Stritcture of Flame. — A candle-flame (Fig. 6) or oil-flame is 
composed of intensely heated material; the central portion is un- 
burnt gas, the next envelope is formed of partially burnt and 
very dense gaseous and solid particles sufliciently highly heated 
to give light, and the outer cone of completely burnt gases. In 
the figure the sharpness of limit of these cones is purposely 



HYDROGEN. 29 

somewhat exaggerated. Air made by any mechanical contri- 
vance to mix with the gas in the interior of a flame at once burns 
up, or perhaps prevents the formation of, dense gases; giving a 
hotter, but non-luminous jet. The air-gas lamps (Fig. 7), or 
"Bunsen" gas-burners, commonly used in chemical laboratories, 
are constructed on this principle; their flame has the additional 
advantage of not yielding a deposit of soot. 

In the air-gas burner coal-gas escaping from a small orifice at 
the bottom of the upright tube draws in and mixes with rather 
more than twice its volume of air (supplied through adjacent 
holes). The mixture, when kindled, only burns at the end of the 
upright tube, and not within it, partly because the metal of the 
burner, by conducting heat away, cools the mixture below the 
temperature at which it can ignite: partly because the velocity 
with which the mixture flows out is greater than the rate at which 
such a mixture ignites; and partly because the proportion of air 
to gas in the mixture is insufficient for perfect combustion, the 
external air immediately surrounding the flame contributing ma- 
terially to the complete combustion of the gas. In the Davy 
safety-lamp advantage is taken of the rapidity with which a sur- 
face of wire gauze conducts away heat; a wire-gauze cage sur- 
rounds an oil-flame; an inflammable mixture of gas (fire-damp) 
and air can pass through the gauze and burn inside; but the 
flame cannot, ordinarily, be communicated to the mixture out- 
side, because the metal of the gauze and of the other parts cools 
down the gas below the temperature at which combustion can 
continue. 

Properties of Hydrogen (continued). — Gaseous hydrogen 
is the lightest substance known. It is used for filling bal- 
loons, but has been, to some extent, superseded by coal-gas 
because coal-gas, though not so light, is cheaper and more 
easily obtained. The lightness of hydrogen may be rendered 
evident by the following experiment: — Fill two test-tubes 
with the gas, and hold one with its mouth downwards and 
the other with its mouth upward. The hydrogen will have 
escaped from the latter in a few seconds, whereas the former 
will still contain the gas after the lapse of many seconds. 
This may be proved by applying a lighted match to the 
mouths of the tubes. 

The relative loeight or specific gravity of oxygen is nearly six- 
teen times that of hydrogen. A vessel holding one grain of hy- 
drogen will hold nearly sixteen grains of oxygen. The relation 
of the weight of hydrogen to air is as 1 to 14.44, or as 0.0()9o to 
1.0. One grain of hydrogen by weight measures about '11 fluiil 



30 NON-METALLIC ELEMENTS. 

ounces, and, therefore would about fill a common wine-bottle. 
Such a bottle would, at ordinary temperatures, hold about 14| 
grains of air, or about 16 grains of oxygen. 

Memorandum. — It is desirable to retain two tubes of hydrogen 
for use in subsequent experiments. 

Diffusion of Gases.— Hydrogen cannot be kept in such ves- 
sels as the inverted test-tube of the above experiment ; for, though 
much lighter than air, it diffuses downward into the air, while the 
air, though much heavier, diffuses upward into the hydrogen. 
This power of diffusion is possessed by all gases. The rates of dif- 
fusion of the different gases are inversely proportional to the 
square roots of the densities of the gases {Graham). Thus hydro- 
gen diffuses four times faster than oxygen. The great and impor- 
tant property of diflFiision suggests that the particles of gases are 
always moving, never at rest ; how otherwise could gases diffuse 
into each other as they do, notwithstanding the opposing influ- 
ence of gravitation ? Diffusion strongly supports this (Clausius's) 
kinetic (/tZvfw, kineo, I move, or put in motion) theory of the 
physical condition of gases. 

PHOSPHORUS. 

Appearance and Source. — Phosphorus {Phosphorus, U. S. P.) 
is a solid element, in appearance and consistence resembling 
white wax ; but it gradually becomes yellow by exposure to light. 
It is a constant constituent of bones, and may be prepared from 
them by a process which will be described subsequently. 

Caution. — Phosphorus, on account of its great affinity for oxy- 
gen, takes fire very readily in the air, and should therefore be 
kept under water. When wanted for use, it must be cut under 
water. It is employed in tipping lucifers though red or amor- 
phous phosphorus is less objectionable for this purpose. 

Experiment. — Dry a piece of ordinary phosphorus, about 
the size of a pea, by quickly and carefully pressing it between 
the folds of porous (filter or blotting) paper ; place it on a 
plate, and ignite it by touching it with a piece of warm wire 
or wood. The product of combustion is a dense white suffo- 
cating smoke, which must be confined at once by placing an 
inverted tumbler, or beaker, or other similar vessel over the 
phosphorus. The fumes rapidly aggregate, and fall in white 
flakes on the plate. When this has taken place, and the 
phosphorus is no longer burning, moisten the powder with a 
drop or two of water, and observe that some of the water is 
converted into steam, an effect due to the intense affinity with 
which another portion of the water and the powder have com- 
bined, with the evolution of heat. 



NITROGEN. 



31 



The powder produced by the combustion of phosphorus is 
termed phosphoric anhydride ; the combination of the latter with 
the elements of water produces a variety of phosphoric acid which 
dissolves in the water and forms, on standing, a dilute solution of 
ordinary phosphoric acid. The Diluted Phosphoric Acid of the 
Pharmacopoeia is a similar solution, made in a somewhat different 
way, and of definite strength. 



NITROGEN. 

Source. — The chief source or this gaseous element is the 
atmosphere, nearly four-fifths of which consists of nitrogen 
(whilst roughly one-fifth is oxygen). 

Preparation. — Burn a piece of dry phosphorus, the size of 
a pea, in a confined portion of air. The oxygen is thus re- 
moved, and the nitrogen remains. The readiest mode of per- 
forming this experiment is to fix a piece of earthenware (the 
lid of a small porcelain crucible answers very well) on a thin 
piece of cork, so that it may float in a dish of w^ater (Fig. 8). 
Place the dry phosphorus on the lid, ignite with a warhi rod, 
and then invert a tumbler, or any glass vessel of about a half- 
pint capacity, over the burning phosphorus, so that the mouth 
of the glass may dip into the water. Let the arrangement 
rest for a short time, for the flakes of phosphoric anhydride to 
subside and dissolve in the water, and then decant the gas into 
test-tubes as indicated in Fig. 9, using a tub or other vessel of 

Fig. 8. Fig. 9. 




Preparation of nitrogen. 



Decantation of gases. 



sufficient depth to admit of the glass containing the nitrogen 
being turned on one side without air gaining access. 

Larger quantities of nitrogen may be obtained in the sanu^ way. 
Other combustibles, as sulphur or a candle, might be used to burn 



32 NON-METALLIC ELEMENTS. 

out the oxygen gas from the air, but none answer so quickly and 
completely as phosphorus, added to which, the products of their 
combustion would not always be dissolved by water, but would re- 
main mixed with the nitrogen. 

Memorandiua. — The statement concerning the composition of 
the air is roughly confirmed in isolating nitrogen, about one-fifth 
of the volume of the air originally in the glass vessel having 
disappeared, its place being occupied by water. 

Properties. — Nitrogen, like oxygen and hydrogen, is color- 
less, tasteless, and odorless. By pressure, Cailletet and Pictet 
condensed it to a liquid. Wroblewski and Olszewski obtained 
it some quantity as a nearly colorless, transparent fluid, which 
congeals, by its own evaporation, to a white snow-like solid. 
It is only slightly soluble in water. Free nitrogen is distin- 
guished from most other gases by the absence of any charac- 
teristic or positive properties. Apply a flame to some con- 
tained in a tube ; it will be found to be incombustible. Im- 
merse a lighted match in the gas ; the flame is extinguished, 
show^ing that nitrogen is a non-supporter of combustion. 

Nitrogen is nearly fourteen times as heavy as hydrogen. 
The free nitrogen in the air acts as a dilutent of the energetic 
oxygen, with which it forms merely a mechanical mixture. 

The air is nearly fourteen and a half (14.44) times as heavy as 
hydrogen. It may be liquefied and solidified. Its average com- 
position, including minor constituents (which will be referred to 
subsequently), is as follows : — 

Composition of the Atmosphere. 

In 100 volumes. 

Oxygen 20.66 

Nitrogen 76.951 

Argon 94 

Carbonic anhydride .034 

Aqueous vapor 1,40 

Ammonia, nitric acid, carburetted ] 

hydrogen, hydrogen, ozone, helium, I traces. 

krypton, neon, xenon ...'.) 
Sulphuretted hydrogen, sulphurous \ traces in 

anhydride ) towns. 

Pure dry air, freed from carbonic anhydride, etc., is remarkably 
constant in composition, and contains approximately : — 

Percent. Percent, 

by volume, by weight. 

Nitrogen (including argon, etc.) . . 79.04 76.9 

Oxygen 20.96 23.1 



CHLORINE. 33 

Free Nitrogen and Combined Nitrogen. 

Notwithstanding the comparative inactivity or negative charac- 
ter of nitrogen in its free condition — that is, when uncombined 
with other elements — this element, when combined with hydro- 
gen, carbon, oxygen, etc., is a constituent of a large number of 
important substances, including the ammonium compounds, the 
various cyanogen compounds, the extensive group of salts called 
nitrates, the valuable medicinal agents known as alkaloids, the 
various albuminoid and coUagenic matters characteristic of the 
tissues of animals and plants, and so forth. Free nitrogen is not, 
however, altogether inactive, for the nitrogen of the air appears to 
be absorbed and assimilated by some plants — certain crops con- 
taining more nitrogen than the soil and manure in which they 
grew. The absorption is efiected by means of nodules which oc- 
cur on the roots of clover and other leguminous plants ; these are 
the dwelling-places of microorganisms, and it is through their 
agency that the soil in which such plants grow becomes richer in 
nitrogen. Experiments have been made with a view to inducing 
these organisms to live on the roots of graminaceous plants, for if 
this, could be done a great saving of artificial manures could be 
effected. 

ARGON. KRYPTON. NEON. 

It has long been known that when nitrogen is prepared from 
atmospheric air, the gas obtained is slightly heavier than nitrogen 
prepared from nitrates or from ammonia. The investigations of 
Eayleigh and Eamsay have proved that this is due to the presence 
of another gas, heavier than nitrogen, to which, on account of 
its apparent chemical inactivity, they gave the name argon {a, 
without, epyov, ergon, work). Its density is about 19. It is 
present in atmospheric air to the extent of nearly 1 percent. 
Recently a compound of argon with carbon has been obtained by 
the passage of electricity between thin carbon poles in an atmos- 
phere of argon; and experiments show that it probably combines 
with the vapor of magnesium at a very high temperature. Argon 
and helium occur with nitrogen in the gases of many naturally 
aerated waters. 

Ramsay obtained another element from atmospheric air, to 
which he gave the name Krypton (KpviTTog, kn/ptos, hidden); 
traces only are present. Ramsay and Travers subsequently an- 
nounced the presence of another element. Neon (vtof, neos, new), 
and Ramsay Xenon. 

CHLORINE. 

Source. — The chief source of this element is common salt, 
more than half of which is chlorine. 
3 



34 



NON-METALLIC ELEMENTS. 



Preparation. — About a quarter of an ounce each of salt 
and of black manganese oxide are mixed, placed in a test- 
tube, and covered with water ; on adding a small quantity of 
sulphuric acid, evolution of chlorine commences. For the 
mode of collection see the following paragraphs. 

Another process. — As the action of the sulphuric acid on 
the salt in the above process is mainly to give hydrochloric 
acid, the latter acid (about 4 parts) and the black mangan- 
ese oxide (about 1 part) may be used in making chlorine, 
instead of salt, sulphuric acid, and black manganese oxide. 

Collection and Properties. — Free chlorine is a suffocating 
gas. Care therefore must be observed in experimenting with 
this element. As soon as its penetrating odor indicates that 
it is escaping from the test-tube, the cork and delivery-tube 
(similar to that used in making oxygen) should be fitted on, 
and the gas led to the bottom of another test-tube containing 
water (Fig. 10). When thirty or forty small bubbles have 



Fig. 10. 



Fig. 11. 




Preparation of chlorine. 

passed, their evolution being assisted by slightly heating the 
generating tube, the latter should be removed to the cup- 
board usually provided in laboratories for performing opera- 
tions with noxious gases, or be dismounted and the contents 
carefully and rapidly washed away. The water in the col- 
lecting-tube will now be found to smell of the gas, chlorine 
being soluble in about half its bulk of water. 



Larger quantities may be made from hydrochloric acid and 
black manganese oxide (4 to 1) in a flask fitted with a deliverv^- 
tube, the flask being supported over a flame by the ring of a 



CHLORINE. 35 

retort-stand (Fig. 11). A piece of cardboard on the neck of the 
collecting-bottle, as indicated in the figure, retards diffusion of 
chlorine from the bottle during the process of collection. 

Memorandum. — Flasks and similar glass vessels are less liable 
to fracture if protected from the direct action of the flame by being 
placed on a piece of wire gauze about 6 inches square, or on a 
sand-bath, that is, a saucer-shaped tray of sheet iron on which a 
thin layer of sand is placed. 

During these manipulations the operator will have noticed 
that chlorine is of a light yellowish-green color. The tint is ob- 
servable when the gas is collected in large vessels. As chlorine 
is soluble in water (2^ vols, in 1 vol. at 60"^ F., 15.5° C), it can- 
not be economically stored over that liquid. Being, however, 
nearly two and a half times as heavy as air, the gas may be col- 
lected by simply allowing the delivery-tube to pass to the bottom 
of a dry test-tube or dry bottle (Fig. 11). 

An important property of free chlorine is its bleaching 
power. Prepare a colored infusion by placing a few chips of 
logwood in a test-tube half full of hot water. Pour off some 
of this red infusion into another tube and add a few drops of 
chlorine-water; the red color is rapidly destroyed. 

Free chlorine readily decomposes offensive effluvia; it is one of 
the most powerful of deodorizers. It also decomposes putrid and 
infectious matter; it is one of the best of disinfectants. {Antiseptics 
are substances which prevent putrefaction. ) 

Combination of Hydrogen with Chlorine, forming Hydro- 
chloric Acid. — If an opportunity occurs of generating chlorine 
in a closed chamber or in the open air, a test-tube, of the 
same size as one of those in which hydrogen has been retained 
from a previous operation, is filled with the gas. The hydro- 
gen-tube is then inverted over that containing the chlorine, 
the mouths being kept together by encircling them with a 
finger. After the gases have mixed, the mouths of the tubes 
are quickly brought into contact with a flame, when explosion 
occurs and fumes of a compound of hydrochloric acid gas 
with the moisture of the air are formed. The Hydrochloric 
Acid of pharmacy (Acidum Hydrochloricum, U. S. P.) is a 
solution of this gas (made in a more economical way) in 
water. 

The foregoing experiment affords evidence of the powerful 
affinity of chlorine and hydrogen for each other. Chlorine dis- 
solved in water will, in sunlight, slowly remove hydrogen from 



} 



36 NON-METALLIC ELEMENTS. 

some of the water and liberate oxygen. The bleaching power of 
chlorine is generally referred to this indirect oxidizing effect which 
it produces in presence of water; for dry chlorine does not bleach. 

Density. — Chlorine is more than 35 times as heavy as hy- 
drogen. A wiue-bottle would hold about 35 grains. 

SULPHUR, CARBON, IODINE. 

The physical properties (color, hardness, weight, etc.) pos- 
sessed by these elements, when they are in the free state, are 
probably familiar to the student. Some of their leading 
chemical characters will also be understood when a few facts 
concerning each are made the subject of experiment. 

Sulphur. — Burn a small piece of sulphur ; a penetrating odor 
is produced, due to the formation of a colorless gas. This 
product is a chemical compound formed by the union of the 
oxygen of the air with the sulphur. It is termed sulphurous 
anhydride (or sulphurous acid gasj. 

Carbon, in a more or less pure condition, is familiar, in the 
free form, as soot, coke, charcoal, graphite (or plumbago, po]> 
ularly termed blacklead), and diamond. The presence of 
combined carbon, in wood and in other vegetable and animal 
matter, is at once rendered evident by heat. Place a little 
tartaric acid on the end of a knife in a flame; the blackening 
that occurs is due to the separation of carbon. The black 
matter at the extremity of a piece of half-burned wood also 
is free carbon. 

Carbon, like hydrogen, phosphorus, and sulphur, has a great 
affinity for oxygen at high temperatures. A striking evidence of 
that affinity is the evolution, during its combustion, of sufficient 
heat to make the materials concerned red or even white-hot. 
When ignited in the diluted oxygen of the air, carbon simply 
burns with a moderate glow, as seen in an ordinary coke or char- 
coal fire ; but when ignited in pure oxygen, the intensity of its 
combustion is greatly exalted. The product of the combination 
of the two elements, if the oxygen be in excess, is an invisible gas 
termed carbonic anhydride (or carbonic acid gas) ; if the carbon 
be in excess and the temperature very high, another invisible gas, 
termed carbonic oxide, results. 

Iodine. — A prominent chemical characteristic of free 
iodine is its great affinity for metals. Place a piece of iodine, 
about the size of a pea, in a test-tube with a small quantity of 
water and add a few iron filings or small nails. On gently 



THE ELEMENTS. 37 

warming this mechanical mixture, or even shaking, if longer 
time be allowed, the color and odor of the iodine disappear ; 
it has chemically combined with the iron — a chemical com- 
pound has been produced. If the liquid be filtered, a clear 
aqueous solution of the compound of the two elements is ob- 
tained. 

This compound is an iodide of iron. Its solution, made as 
above, and mixed with sugar, forms, when of a certain 
strength, the ordinary Syrup of Ferrous Iodide of pharmacy 
{Syrupus Ferri lodidi, U. S. P.). The solid iodide is ob- 
tained on removing the water of the above solution by evap- 
oration. 

Sulphur and Iron, also, when very strongly heated, chemically 
combine to form a substance which has none of the properties of a 
mixture of sulphur and iron — that is, has none of the characters 
of sulphur and none of iron, but new properties altogether. The 
product is termed Ferrous Sulphide. Its manufacture and uses 
will be alluded to in treating of the compounds of iron ; it is men- 
tioned here as a simple but striking illustration of the difference 
between a chemical compound and a mechanical mixture. 

THE ELEMENTS. 

From the foregoing statements a general idea will have 
been obtained of the nature of several of the more frequently 
occurring elements. Some additional facts concerning them 
may be gathered from the following Table, which gives the 
origin of the names of a number of the elements : — 

Aluminium . . The metallic basis of alum was at first confounded 
with that of iron sulphate, which was the alum of 
the Eomans, and was so-called in allusion to its 
tonic proj)erties, from alo, I nourish. 

[Ammonium] . This body is not an element ; but its components 
exist in all ammonical salts, and ai^pavently play 
the part of such elements as potassium and sodium. 
Sal ammoniac (ammonium chloride) was first ob- 
tained from near the temple of Jupiter Amnion in 
Libya ; hence the name. 

Antimony . . . Sri^i (stibi), or CTTi/ufxi (stimmi), was the Greek name 
(Stibium) for the native antimony sulphide. The word an- 

timony is vSaid to be derived from avrl (anti) 
against, and moinc, French for mouk, from the fact 
that certain monks were iH)isoned by it. 

Argron .... From a, witliout ; epyov (ergon), work. 

Arsenic .... ApaevLKbv (arsenikon), the Greek name for orpi- 
ment, an arsenic sulphide. Common white arsoiic 
is arsenic trioxide. 



THE ELEMENTS. 



Barium .... From /SapO? ( barus) heavy, in allusion to the high spe- 
cific gravity of '"heavy spar," the most common 
of the barium minerals. 

Bismuth . . . Slightly altered from the German Wimnuth, derived 
from' Wiesematte, "a beautiful meadow," a name 
given to it originally by the old miners in allusion 
to the prettily variegated tints presented by the 
freshly exposed surface of this crystalline metal. 

Boron .... From horah or haurak, the Arabic name of borax, the 
substance from which the element was first ob- 
tained. 

Bromine . . . From ^p^mo? (bromos), a stink. It has an intoler- 
able odor. 

Cadmium . . . KaS/aeia (kadmeia) was the ancient name of calamine 
(zinc carbonate), with which cadmium carbonate 
was long confounded, the two often occurring 
together. 

Calcium . . . Calx, lime., calcium oxide. 

Carbon .... From carho, coal, which is chiefly carbon. 

Carium .... Discovered in 1803, and named after the planet 
Ceres, which was discovered on Jan. 1, 1801. 

Chlorine . . . From x^'^po'^ (chloros) greeyi, the color of this ele- 
ment. 

Chromium . . . From xP'-J/^a (chroma) color, in allusion to the char- 
acteristic appearance of its salts. 

Cobalt .... Cohalus, or Kobold, was the name of a demon sup- 
posed to inhabit the mines of Germany. The 
ores of cobalt were formerly troublesome to the 
German miners, and hence received the name 
their metallic radical now bears. 

Copper (Cuprum) From Cyprus, the name of the Mediterranean island 
where this metal was first worked. 

Fluorine . . . From fluo, I flow. Calcium fluoride, its source, is 
commonly used as a flux in metallurgic opera- 
tions. * 

Gold (Aurum) . Anriim (Latin) from a Hebre'sr\word signifying the 
color of fire. 
Gold : a similar word is expressive of bright yelloiv in 
several old languages. 

Hydrogen . . . From vSup (hudor) icater, and ye'veo-is (genesis), gener- 
ation, in allusion to the product of its combustion 
in air. 

Iodine .... From lov (ion) a violet, and eI8o? (eidos) likeness, in 
reference to the color of its vapor. 

Iron (Ferrum) . Prehistoric. The spelling may be from the Saxon 
iren, the pronunciation from the Gothic "iarn.^' 
The derivation is perhaps Aryan; it probablj'- 
originally meant metal. 

Lead (Plumbum) The Latin expresses " something heavj' " ; the Saxon 
bed has a similar signification. 

Lithium .... From Ai'deios (litheios) stony, in allusion to its sup- 
posed existence in the mineral kingdom only. 

Magnesium , . From Magnesia, the name of the town (in Asia 
Minor) near which the substance now called 
"native magnesium carbonate" was first dis- 
covered. 

Manganese . . Probably the slightly altered word magnesia, with 
whose compounds those of manganese were con- 
founded till 1740. 



DERIVATION OF NAMES. 



39 



Mercury . . . 
(Hydrarg-yrum) 



Nickel . . 

Nitrogen . 
Oxyg-en . . 

Phosphorus 
Platinum . 



Potassium . 
(Kalium) 



Silicon .... 

Silver .... 
(Arg-entum) 

Sodium (Natrium) 



Strontium . . 



Sulphur 



Tin (Stannum) 



Zinc 



Hydrargyrum, from u5wp (huclor) water, and apyvpoq 
(arguros) silver, in allusion to its liquid and lus- 
trous cliaracters. Mercury, after the messenger 
of the gods, on account of its susceptibility of 
motion. The old name quicksilver also indicates 
its ready mobility and silvery appearance. 

Nickel from nil, worthless. Nickel ore was formerly 
called Kupfernickel, false copper. When a new 
element was found in the ore, the name nickel 
was retained for it. 

From virpov (nitron) and yei'eo-t? (genesis) generation, 
i. e., generator of nitre. 

From 6fi<s (oxus) acid, and ^eVeo-is (genesis) generation, 
i. e., generator of acids. When first discovered it 
was supposed to enter into the composition of all 
acids. 

*w? (phos) light, and ^e'petv (pherein) to bear. The 
light it emits may be seen on exposing it in a dark 
room. 

From platina (Spanish), diminutive of plata, silver. 
It somewhat resembles silver, but is less white and 
lustrous. 

Kalium from kali, Arabic for ashes (see Sodium). 
Manufactories in which compounds of potassium 
and allied sodium salts are made, are called alkali- 
works to this day. Potassium, from potash. Pot- 
ash so-called because obtained by evaporating the 
lixivium of wood-ashes in pots. 

From silex, Latin for flint, which is nearly all silica 
(silicon oxide). 

"Apvvpos (arguros) silver, from apyh^ (argos) white. 
Words resembling the term silver occur in several 
languages, and indicate a white appearance. 

Natrium, from natron, the old name for certain 
natural deposits of sodium carbonate. Sodium, 
from soda, the name originally given to the resi- 
due of the combustion of marine plants. Soda 
ashes were chemically distinguished from pot- 
ashes by Duhamel in 1736. Previously both were 
simply kali or ashes from two difierent sources. 
Sir Humphry Davy first isolated the two metals, 
in 1807. 

This name is commemorative of Strontian, a mining- 
village in Argyleshire, Scotland, in the neighbor- 
hood of which the mineral known as strontianite, 
or strontium carbonate, was first found. 

From sal, a salt and TrOp (pur) fire, indicating its com- 
bustible qualities. Its common name, brimstone, 
has the same meaning, being the slightly altered 
Saxon word, brynstone, i. e., burnstone. 

Both words are possibly corruptions of the old Brit- 
ish word staen, or the Saxon word stau, a stone. 
Tin was first discovered in Cornwall, and the ore 
(an oxide) is called tinstone to the present day. 

From Ger. Zinn, tin, with which. Zinc seems at first 
to have been confounded. 



40 NUMERICAL AND PHYSICAL MATTERS. 

QUESTIONS AND EXEECISES. 

Distinguish between the art and the science of chemistry. — Of how 
many elements is terrestrial matter composed? Enumerate the chief 
non-metallic elements. — Describe a process for the preparation of oxy- 
gen. — How are gases usually stored ?— Mention the chief properties of 
oxygen. — What is the source of auimal warmth ? — State the proportion of 
oxygen in air. — Is the proportion constant, and why? — Give a method 
for the elimination of hydrogen from water. —State the properties of 
hydrogen. — Why is a mixture of hydrogen and air explosive ? — Explain 
the effects producible by the ignition of large quantities of coal-gas and 
air. — What is the nature of combustion? — Define a combustible and a sup- 
porter of combustion. — Describe the structure of flame. — State the principle 
of the Davy safety-lamp. — In what proportion is hydrogen lighter than 
oxygen? — What do you mean by diffusion of gases? — State Graham's law 
concerning diffusion. — Name the source of phosphorus, and give its char- 
acters. — Why does phosphorus burn in air? — What gas remains when 
ignited phosphorus has removed all the oxygen from a confined portion 
of air?— Mention the properties of nitrogen. — What ofiice is fulfilled by 
the nitrogen of the air? — State the proportions of the chief constituents 
of air. — Mention the minor or occasional constituents of air. — What is the 
proportion by weight of nitrogen to oxygen in the atmosphere ?-T-Give 
the specific gravity of nitrogen. — How is chlorine prepared ? — Enumerate 
the properties of chlorine. — Define the terms deodorizer and disinfectant. — 
Explain the bleaching effect of chlorine. — What proportion of hydrogen 
to chlorine is necessary for the formation of hydrochloric acid gas? — State 
the prominent chemical and physical characters of sulphur. — State those 
of carbon. — State those of iodine. — Give the derivations of the names of 
some of the elements. 



NUMERICAL AND PHYSICAL MATTERS OF SPE- 
CIAL IMPORTANCE IN ELEMENTARY 
CHEMISTRY. 

The Metric System of "Weights and Measures (the word 
metric is from the Greek /jJzp<», metron, measure) which is 
now in common use in most of the countries of Europe and 
elsewhere, presents several advantages over the older systems. 
The two chief advantages of the metric system are, that cer- 
tain of the units are related to one another in an exceedingly 
simple and practical manner ; and that the system is a deci- 
mal one throughout, and is thus in complete harmony with 
the universal mode of counting. 

The metric system of weights and measures is founded on 
the metre. Fig. 1 2 represents a pocket folding' measure the 
tenth part of a metre in length, divided into 10 centimetres, 
and each centimetre into 10 millimetres. 

The units of the system, with their multiples and submul- 
tiples, are as follows: — 

Length. — The Unit of Lenrjth is the Metre, derived from 



THE METRIC SYSTEM. 



41 



the measurement of the Quadrant of a Meridian of the Earth. 
(Practically it is the length of certain carefully preserved 
bars of metal, from which copies have been taken.) 

Surface. — The Unit of Surface is the Are, which is the 
square of Ten Metres. 

Fig. 12. 



uii]iiniiiniiin|iMi|iiii|iiii|Miiiiiii[i[ inn 



ri]TiTi 



M 



\\\\\m\ 



The decimetre. 

Capacity. — The Unit of Capacity is the Litre. It was 
originally intended that the Litre should be exactly one 
Cubic Decimetre, but the Standard Litre although very 
nearly in conformity with this intention is not absolutely so. 
(1 Litre = 1.00016 Cubic Decimetre.) In the U. S. Phar- 
macopoeia the Cubic Centimetre is understood to be identical 
with the millilitre, or thousandth part of a litre. 

Mass. — The Unit of Mass is the Gramme, ^ which is the 
mass of that quantity of distilled water, at its maximum den- 
sity point (4° C.) which occupies the space of the one- 
thousandth part of a Litre (1 Millilitre). 

Table. 

Note. — Multiples are denoted by the Greek words ''Deka," 
Ten, ^^Hecto," Hundred, *'Kilo," Thousand. 
Subdivisions by the Latin words, ''Deci," One-tenth, 
"Centi," One-hundreth, "Milh," One- thousandth. 



Quantities. 


Length. 


Surface. 


Capacity. 


Weight. 


looa 


Kilo-metre 




Kilo-litre 


Kilo-gramme 


100 


Hecto-metre 


Hectare 


Hecto-litre 


Hecto-gramme 


10 


Deca-metre 




Deca-litre 


Deca-gramme 


1 (Units) 


METRE 


ARE 


LITRE 


GRAMME 


.1 


Deci-metre 


. . . 


Deci-litre 


Deci-gramme 


.01 


Centi-metre 


Centiare 


Centi-litre 


Centi-gramme 


.001 


Milli-metre 




Milli-litre 


Milli-gramme 



When the Metric method is exclusively adopted, these ITnits 
and Table, comprising the entire System of Weights and INIeasuros, 
represent all that will be essential to be learned in lion (^f the 
numerous and complicated Tables hitherto in use. Adopting the 
style of elementary books on arithmetic, the table may be ex- 
panded thus: — 

'The word gramme is sometimes, unfortunately written gram, wliich 
too closely resembles the word grain. 



42 NUMERICAL AND PHYSICAL MATTERS. 

10 milligrammes make 1 centigramme; 10 centigrammes make 
1 decigramme; 10 decigranmies make 1 gramme; 10 grammes 
make 1 decagramme, or dekagramme; 10 decagrammes make 1 
hectogramme; 10 hectogrammes make 1 kilogramme; 10 milli- 
litres make 1 centilitre, etc.; 10 millimetres make 1 centimetre, etc. 

Abbreviations. — Metre = m ; decimetre = dm ; centimetre = a7i; 
millimetre = mm ; kilometre = km. Square metre = m^ ; cubic 
metre = m^ ; and so on. Litre — I ; decilitre = dl etc. Kilo- 
gramme = /:g ; decagramme = dkg ; gramme = g ; decigramme = 
dg ; centigramme = eg ; and milligramme = mg. 

The following approximate equivalents of metrical units should 
be committed to memory: 

1 Metre = 3 feet 3 inches and 3 eights. 
1 Are = a square whose side is 11 yards. 

1 Litre = .2642 U. S. liquid gallons 

1 Gramme = 15^ grains. 
The Kilometre is equal to 1100 yards. 
The Hectare = 2V acres nearly. 
The Metric Ton of 1000 Kilogrammes = 19^ cwt. 2 qrs. 20 lbs. 10 oz. 
The Kilogramme = 2 lbs. 3i oz. nearly. 

A litre of water at 39° F. (3.9° C.) weighs 15,432 grains; at 
50° F. (10° C), 15,429 grains; at 60° F. (15.5° C), 15,418 
grains; at 70°F. (21.1°C.), 15,403 grains; and at80°F. (26.7°C.), 
15,383 grains (Pile). 

Decimal Coinage. — In most countries where the metric system 
of weights and measures is employed, a decimal coinage is also 
adopted. This, conjoined with the ordinary decimal method of 
enumerating, which fortunately is in universal use simplifies 
calculations of all kinds. 

WEIGHTS AND MEASURES OF THE METEIC SYSTEM, 
WEIGHTS. 

1 Milligramme = the thousandth part of one grm. or 0. 001 grm. 
1 Centigramme ^ the hundreth " " 0.01 " 

1 Decigramme = the tenth " " 0.1 '* 

1 Gramme = weight of one millilitre of dis- 

tilled water at 4° C. (39.2° F.) 
1 Dekagramme = ten grammes 10.0 " 

1 Hectogramme = one hundred grammes 100.0 " 

1 Kilogramme = one thousand grammes 1000.0 (1 kilo). 

MEASURES OF CAPACITY. 

1 Millilitre = the volume at 4° C. of 1 gramme of water. 

1 Centilitre = " " 10 '' " 

1 Decilitre = " " 100 '' " 

1 Litre = " '' 1000 '' '' 



THE METRIC SYSTEM, 



43 



MEASURES OF LENGTH. 

1 Millimetre = the thousandth part of one metre or 0. 001 metre 

1 Centimetre = the hundreth " " 0.01 " 

1 Decimetre = the tenth " " 0.1 " 

1 Metre = " " 0.0 



RELATIONS BETWEEN THE VARIOUS UNITS OF WEIGHTS AND 
MEASURES IN USE. 



1 Metre 
1 Yard 



Litre 

Liquid gallon 
Fluidounce 
Kilogramme 
Pound 



1 Ounce 

1 Apothecaries' 

ounce 
1 Grain 



39. 3700 inches 
00.914402 metre ' 

0.264170467 liquid gallon 

3.785434 litres 
29.5737 millilitres 

2.20462 pounds or 15432.35639 grains 
453.5924277 grammes 
28.3495 grammes 

31.10348 grammes 

64.7989 milligrammes 



COMPARISONS OF WEIGHT AND VOLUME AT MAXIMUM DENSITY. 
IN VACUO. 

1 Litre of water weighs 1 Kilogramme 

1 Gallon of water weighs 3785.434 grammes or 58418.1444 

grains. 
1 Fluidounce of water weighs 29.5737 grammes or 456.392 

grains. 
1 Apothecaries' Ounce of water measures 31.10348 millilitres 

or cubic centimetres, or 504. 829 minims. 



QUESTIONS AND EXEECISES. 

Mention some advantages of the metric (decimal) system of weights 
and measures. — What is the chief unit of the metric system ? — Mention 
the names of the metric units of surface, capacity, and mass, and state 
how they are derived from tlie unit of length. — How are multiples of 
metric units indicated? — State the designation of submultiples of metric 
units. — How many metres are there in a kilometre? — How many milli- 
metres in a metre? — How many grammes in 5 kilogrammes? — How many 
milligrammes in 13i^ grammes? — In 1898 centigrammes how many 
grammes? — In a metre measure 5 centimetres wide and 1 centimetre 
thick, how many cubic centimetres ?— How many litres are contained 
in a cubic metre of any liquid? — State the equivalent of the metre in 
feet and inches. — How many square yards in an are? — How many 
fluidounces in a litre?— 7H0W many ounces in a kilogramme? 

Measureinenf of Temperature. Fahrenheit and Centigrade Ther- 
mometer Scales (Fig. 13). — The measurement of temperature is 
carried out by aid of the thermometer,^ the construction of which 
' From OepixTf, therme, heat, and /neVpoi', metfon, measure. 



44 



NUMERICAL AND PHYSICAL MATTERS 



• • 



I 



is described in the Section on Quantitative Measurements. The 
thermometers employed in the United States are practically always 
graduated in accordance with either the Fahrenheit or the Centi- 
-p -.3 grade scale. On the Centigrade (C.) scale 

Fahreuhei't. Centigrade, t^^, freezing-point of water is marked zero, 
and the boiling-point 100 ; on the Fahrenheit 
(F. ) scale the zero is placed 32 degrees below 
the freezing-point of water, and the boiling- 
point is 212. Conversions of expressions of 
temperatures in degrees F. into the corres- 
ponding expressions in degrees C, and con- 
versions in the reverse direction, can be made 
by applying the following rules : — 

1. F. to C. Substract 32, rnultiply the re- 
mainder by 5, divide the product by 9. 

Example: — 68° F. Find the corresponding 
°C 

68-32 = 36 ; 36X5 = 180--9 = 20. 68° F. 
corresponds to 20° C. 

2. C. to F. Multiply by 9, divide the pro- 
duct by 5, add 32. 

Example: — 52° C. Find the corresponding 
°F. 
468 ^ 5 = 93. 6; 93. 6 + 32 = 125. 6. 

F. 

The following is an easily remembered rule for converting from 
°C. to °F. :— 

Double the number of degrees C, substract from the result its 
tenth part, add 32. 

Thus, applying the rule to the example immediately preceding: 

52X2 = 104; 104-10.4^=93.6; 93.6 + 32 = 125.6. 

52 °C. corresponds, as above, to 125.6 °F. 

Care must be taken in dealing with expressions of temperature 
having the - sign; that is, with expressions representing tempera- 
tures below the zero points of the respective scales. 

Example:— -4 °F. Find the corresponding °C. 

-4-32= -36; - 36 X 5 = - 180 ^ 9 = - 20. 

-4 °F. corresponds to - 20 °C. 

Mewmremenf of Atmospheric Pressure. The Barometer. — The 
analysis of gases and vapors involves determinations of the varying 
pressure of the atmosphere as indicated by the barometer (from 
/3a^)of, bnros, weight, and /jfrpov, rnefron, measure). 

The ordinarrj mercurial barometer is a glass tube 33 or 34 inches 
long, closed at one end, which has been filled with mercury and 
inverted in a small cistern or cup of mercury (Fig. 14). The 



Thermoraetric scales. 
52 X 9 = 468; 

52 °C. corresponds to 125.6^ 



ATMOSPHERIC PRESSURE. 



45 



Fig. 15. 



23; 

28l 



/«v: 




greater part of the mercury remains in the tube, owing to the 
pressure of the atmosphere on the exposed surface of the liquid, 
the average height of the column being nearly 30 inches. In the 
popular form of the instrument, the wheel barometer, the cistern 
is formed by a recurvature of the tube (Fig. 15); on the exposed 

surface of the mercury a float is 
Fig. 14. placed, from which a thread passes 
over a pulley and moves an index 
whenever the column of mercury rises 
or falls. The glass tube and con- 
tained column of mercury are alto- 
gether enclosed, the index alone 
being visible In the form first 
described the upper end of the glass 
tube and mercurial column are ex- 
posed, and the height of the mer- 
cury is ascertained by direct obser- 
vation. 

The aneroid barometer (from a, a, 
without, and vijpbq, rieros, fluid) con- 
sists of a small, shallow, vacuous 
metal drum, the sides of which ap- 
proach each other when an increase 
of atmospheric pressure occurs, their 
elasticity enabling them to recede 
toward their former position on a 
decrease of pressure. This motion 
is so multiplied and altered, in direc- 
\/' tion by levers, etc., as to act on a 
Barometer, hand traversing a plate on which Barometer. 

are marked numbers corresponding 
with those showing the height of the mercurial column of the 
ordinary barometer by which the aneroid was adjusted. The 
Bourdon barometer (from the name of the inventor) is a modified 
aneroid, containing in the place of the round metal box a flattened 
vacuous tube of metal bent nearly to a circle. These barometers 
are also used for measuring the pressure in steam-boilers, etc. 
Under the name of pressure-gauges they are sold to indicate 
pressures of as much as 500 pounds per square inch or higher. 
Aneroid barometers, on account of their portability (they can be 
made of 1 to 2 inches in diameter and less than an inch thick), 
are handy companions for ascertaining the heights of hills, 
mountains, and other elevations. 



46 NUMERICAL AND PHYSICAL MATTERS. 

QUESTIONS AND EXERCISES. 

Give rules for the conversion of degrees C. into degrees F., and of 
degrees F. into degrees C. — Name the degree C. equivalent to 60° F. — 
What degree C. is represented hy - 4° F. ? — Mention the degree F. 
indicated by 20° C— Convert 100° F. into degrees C— How are varia- 
tions in atmospheric pressure determined ? — Explain the construction 
and mode of action of barometers. — In what respect does a wheel- 
barometer differ from an instrument in which the readings are taken 
from the top of the column of mercury? — Describe the construction 
and mode of action of an aneroid barometer. 

Relation of the Volume of a Gas to Pressure and to Temperature. 

The volume occupied by any given quantity of a gas varies {a) 
with variations in the pressure to which it is subjected; and {b) 
with variations in its temperature. The amount of the variation 
in vohime for any given change in either of these conditions is 
practically independent of the nature of the gas, since (within 
moderate ranges of pressure and of temperature) it is approx- 
imately the same for all gases, unless these are near their 
liquefying points. The observed variations take place ajjproxi- 
mately in accordance with the following laws: — 

Boyle's Law. — When the temperature of a quantity of gas is 
kept constant, the volume which the gas occupies varies inversely 
as the pressure. When the original pressure is doublexi, the volume 
is diminished to one-half ; when it is trebled, the volume is 
diminished to one-third ; w^hen it is halved, the volume is doubled, 
and so on. The pressure under w^hich a gas is measured is expressed 
in millimetres of mercury — that is, by the height in millimetres 
of a column of mercury capable of counter-balancing the pressure 
exerted by the gas. 

Charleses Law.^ — When the pressure under which a quantity of 
gas is measured is kept constant, the volume which the gas occupies 
varies directly as the "absolute" temperature. The absolute 
temperature is obtained by adding 273 to the observed temperature 
of the gas in degrees Centigrade. Suppose that a quantity of gas 
occupies 273 Cc. at 0° C, then the volumes wdiich it is found to 
occupy at the temperatures in Column I. of the following table 
are those given in Column III. Columns II. and III. show how the 
volume varies directly as the absolute temperature. 

I. II. III. 

Temperature Absolute Temperature Volume in 
in°C. ( = t.). (==273 + t.). Cc. 

1 274 274 

2 275 275 
10 283 283 
30 303 303 

—1 272 272 

— 10 263 263 

— 30 243 243 
^ Also occasionally called "Gay Lussac's Law." 



DENSITY. 47 

This table illustrates another way in which Charles's law may 
be stated, viz. , that the volume of a gas is increased or diminished 
by 2YZ ( = 0.00366) of its volume at 0° C. for each degree Centi- 
grade that the temperature of the gas is raised or lowered. 

Standard Temperature and Pressure. — The temperature of C. 
and the pressure of 760 Mm. are termed standard temperature and 
standard pressure respectively. 

It is frequently necessary to calculate, in accordance with the 
foregoing laws, what the volume of a quantity of gas would become 
under new conditions of pressure and of temperature, when its 
volume under stated conditions (original conditions) is known. 
The calculation (which is often termed ^ 'correction for pressure and 
temperature") can be made in all such cases in accordance with 
the following fairly obvious rule: — 

Taking the known volume, 

(1) Multiply by the original pressure, and divide by the new 
pressure; and 

(2) Multiply by the new absolute temperature, and divide by 
the original absolute temperature. 

Example: — A quantity of hydrogen occupies 260 Cc. at 27 C. 
and 750 Mm. Find its volume at 0^ C. and 780 Mm. 

We have here: — Known volume = 260 Cc. ; Original Pressure = 
750 Mm. ; New Pressure =780 Mm. ; Original Absolute Tempera- 
ture = 273 + 27° = 300°; New Absolute Temperature = 273 + 
0° = 273°. 

Proceeding as indicated by the rule given above, we get: 

750 273 

260 X X = 227.5 Cc. 

780 300 

Density. — By the density of a substance we understand the 
number of units of mass of the substance which occupy a unit 
of space. The gramme and the millilitre are adopted as unit of 
mass and unit of space respectively, and the density of a substance 
is then represented by the number of grammes of that substance 
which occupy a millilitre. At 4° Centigrade one gramme of water 
occupies a millilitre, hence at this temperature the density of water 
is = 1 in terms of the above units. 

Relative Densities or Specific Gravities of Liquids and of Solids. — 
Relative densities (or specific gravities) are the densities of other 
substances as compared with that of some substance which is 
chosen as standard. Water at 4° C. (with density assumed = 1) 
would be a theoreticallv perfect standard for the comparison of 
the relative densities of other liquids and of solids. At 4° Centi- 
grade water is at its maximum density point; that is to say, any 
given quantity of water occupies at this temperature a smaHor 
volume than it does at any temperature above or below 4° C. The 
numbers representing the relative densities of solids and of liquids, 



48 NUMERICAL AND PHYSICAL MATTERS. 

in terms of the units and standard referred to above, ^ would thus 
show how many times heavier or lighter the respective substances 
are, bulk for bulk, than water at 4° C. ; or, what is the same thing, 
how many grammes of the respective substances occupy the same 
space as one gramme of water at 4° C. {i.e. 1 millilitre). 

Relative Densities of Gases. — The relative densities (or sjjecific 
gravities) of other gases are usually compared with the density of 
hydrogen, the lightest known gas, which is arbitrarily chosen as 
standard, with density =1. (Formerly air was the standard 
adopted with density=l.) In order to be in a position to compare 
the density of any given gas with that of the standard, it is necessary 
to determine the masses of equal volumes of both gases, under 
the same conditions of pressure and of temperature {see p. 46, and 
the Section on Quantitative Measurements). The numbers repre- 
senting the relative densities of gases show how many times heavier 
the respective gases are, bulk for bulk, than hydrogen under the 
same conditions of pressure and of temperature, or, what is the 
same thing, how many grammes of the respective gases occupy, 
under the same conditions of pressure and of temperature, the 
same sj^ace as one gramme of, hydrogen {i.e. 11.1 litres). 

Vapor Density. — This term is applied to the relative density (or 
specific gravity) of the vapor in the case of any substance which 
is liquid or solid at ordinary temperatures but which is capable of 
being converted into the state of vapor, without undergoing decom- 
position, by a sufficient rise of temperature. Vapor densities are 
thus strictly comparable with the relative densities of gases. {See 
the Section on Quantitative Measurements. ) 



QUESTIONS AND EXEECISES. 

Define Boyle's law.— What does the volume of a litre of hydrogen 
at ordinary atmospheric pressure become when the pressure is doubled, 
halved, quadrupled? — Mention to ways in which the regularity known 
as Charles's law may be stated. — How is the number which represents 
the absolute temperature obtained? — Define standard temperature and 
pressure. — What is the rule for "correcting" the volume of a gas for 
change in temperature and pressure? — What do you understand by the 
terms density, relative density, vapor density? 

The student is recommended to read the following paragraphs on 
the General Principles of Chemical Philosophy carefully once or 
twice, then to study {experimentally, if possible) the succeeding pages, 
returning to and reading over the General Principles from time to 
time until they are thoroughly comprehended. 

* Note, however, that the standard temperature adopted in practice 
for comparing specific gravities is not 4° C, but 25° C. (77° F.). {See 
the Section on Quantitative Measurements.) 



CHEMICAL AND PHYSICAL CHANGES. 49 

THE GENERAL PRINCIPLES OF CHEMICAL 
PHILOSOPHY. 

The Science of Chemistry treats of a particular class of changes 
that matter undergoes. These changes result in the formation of 
new substances — that, is, of substances which are different in com- 
position and properties from the materials out of which they have 
been produced — and they are commonly called chemical changes. 
Such changes may be the result of natural agencies only, as in 
the growth of plants and animals in a wholly natural state, and in 
the transformations tliat the inanimate materials of which the 
earth is composed undergo owing to climatic and other influences ; 
or they may be directed and, so far, controlled by human agency, 
as, for example, in the processes carried out in the chemical labora- 
tory or manufactory. 

Chemical and Physical Changes. — Many well-marked, or typical, 
cases of chemical change are easily recognized as such. Some- 
times, however, it is difficult, and occasionally it is not possible, 
to recognize whether a particular change really is a chemical 
change, or whether it belongs to the class of phenomena called 
physical changes. The existence of any uncertainty arises from 
the difficulty in proving conclusively whether a new substance has 
been produced or not, together with the fact that it is not an alto- 
gether easy matter to define strictly what constitutes the formation 
of a new substance. Familiar examples of physical changes are 
furnished by the transformations of solids into the liquid state (as 
of ice into water) or of liquids into the state of vapor (as of water 
into steam) without any change in the composition of the sub- 
stances. In typical cases, the occurrence of chemical change may 
usually be recognized by the accompanying phenomena character- 
istic of such change. Two of the most important of these phe- 
nomena are: — 

1. The disappearance of the properties of the substance or sub- 
stances tvhich take part in the change, and the formation of a neir 
substance or of new substances possessing other properties. 

A mixture of free oxygen and hydrogen is still a gas ; water, a 
chemical compound of oxygen and hydrogen, is a liquid; here is 
great alteration in properties. Iodine is only slightly soluble in 
water, forming a brown-colored solution, and iron is insoluble ; 
but when iodine and iron are chemically combined, the jiroduct is 
very soluble in water, forming a light-green solution which is 
utterly unlike iron or iodine in any one of its })roi)erties, and in 
which the eye can detect neither iodine nor iron. Tartaric acid 
and sodium carbonate, mixed together in presence of water, give 
rise to other and wholly diflerent chemical compounds, the original 
substances having interacted and formed fresh combinations. 



50 GESERAL PRINCIPLES OF CHEMICAL PHILOSOPHY. 

Baud, sugar, and butter, rubbed together, form a mere mixture, 
from which water would extract the sugar, and ether dissolve out 
the butter, leaving the sand. These examples illustrate how 
chemical action is distinguished, namely, by producing an entire 
change of properties in the resulting substances. 

2. The giving out, or the absorption of heat, during the chartge. 

When coal or a caudle burns in the air, the carbon present in 
the combustible material unites with the oxygen of the atmos- 
phere, with the evolution or giving out of heat. Sulphur, phos- 
phorus, certain metals such as magnesium and zinc, as well as 
manv other substances, likewise burn in the air, with the evolu- 
tion of heat. These instances of combustion are all examples of 
chemical action, and are readily distinguishable as such. 

Besides the two important phenomena noted above as character- 
istic of chemical changes, it is further to be observed that chem- 
ical combination takes place between the substances which enter 
into reaction (interact) in certain definit3 proportions by weight 
only, and not simply in any proportions in which they may, by 
chance or by intention, be mixed together. The quite general 
regularities that have been observed in connection with this matter 
are discussed below under the Laws of Chemical Combination. 

Elements and Compounds. — In modern chemistry the term ele- 
ment is applied to any substance which has not been shown to be 
compound — that is, to possess a composite nature. The word is 
strictly reserved for those substances which the chemist is neither 
able to break up into two or more simpler substances, nor to pro- 
duce by the union of two or more simpler substances. The ele- 
ments are the simplest forms of matter known. The term coin- 
pound is applied to all substances the composite nature of which 
can be proved. The proof may consist in breaking up the com- 
pound into two or more simpler substances by some method of 
decomposition ; or it may consist in building up the compound from 
two or more simpler substances, by causing these to combine — that 
is, by affecting its synthesis} 

Up to the present, about 70 elements have been discovered, and 
more or less minutely examined and described. Of these ele- 
ments, about 40 are either of practical importance themselves, or 
they enter into the composition of compounds which are of prac- 
tical importance. All of the enormous number of chemical com- 
pounds that have been prepared and examined are combinations 
of two or more of the known elements. 

Chemical Ajfinitg is the name applied to that tendency exhibited 
by certain elementary and compound substances to enter into 
fresh combinations with one another so as to form new compounds. 
The name is sometimes applied also to the tendency of substances 

1 The word synthesis is from avvOea-i^, siinthesis, a putting together; anal- 
7/.S/.V, a term often used to designate the reverse operation of decomposi- 
tion, is from aiaAiiw, analud, I resolve. 



LAW OF CHEMICAL COMBINATION. 



51 



to remain combined after combination, with the formation of new 
compounds, has taken place. 

Laws of Chemical Combination. — Chemical combination takes 
place between definite quantities of substances. The more impor- 
tant quantitative relations are expressed by the following laws: 

The Law of Constant Proportions states that the same chemical 
compound is always composed of the same elements, and that 
these elements are present in the compound in the same relative 
proportions by weight. Thus any pure specimen of common salt 
is found on analysis to contain the elements sodium and chlorine 
only, and these are associated with each other in proportions of 
22.88 parts by weight of sodium to 35.18 parts by weight of 
chlorine. Similarly any pure specimen of sulphuric acid contains 
hydrogen, sulphur, and oxygen, associated with one another in the 
proportions of 2 parts by weight of hydrogen to 31.83 of sulphur 
and 63.52 of oxygen. To the general statement of the law of 
constant proportions, it may be added that the mass of (or quan- 
tity of matter contained in) any compound substance is equal to 
the sum of the masses of its constituents. 

The Laio of Multiple Proportions. — The same elements are some- 
times capable of uniting with each other in more than one propor- 
tion by weight. The law of multiple proportions states that, when 
this is the case, the several quantities of one of the elements 
which combine to form two or more compounds with any given 
quantity of the other element, stand in simple multitude relations 
either to each other or to some common submultiple. Thus in 
the two oxides of carbon there are contained : 





Parts by weight 
of Carbon. 


Parts by weight of 
Oxygen. 


Carbonic oxide . 

Carbonic anhydride . . ' . 


12 

12 


16 
32 


and in the two oxides of phosphorus there are cor 


itained : 



Phosphorous anhydride 
Phosphoric anhydride 



Parts by weight of 
Phosphorus, 



62 
62 



Parts by weiglit of 
Oxygon, 



48 (=16x3) 
80 ( = 16x0) 



The Law of Ga^'^eous Volumes states that when gases combine 
with one another, the volumes which unite stand in a sinij)le rela- 
tion to each other and also to the volume of the product when 



52 GENERAL PRINCIPLES OF CHEMICAL PHILOSOPHY. 

this is a gaseous substance. The simple relations of the volumes 
of the combining gases to each other and to the volume of the 
l^roduct in a few cases illustrative of this law, are exhibited in the 
following table: — 



Volumes of Combining gases. 


Volume of product. 


Hydrogen 1, Chlorine 1 
Hydrogen 2, Oxygen 1 
Carbonic oxide 2, Oxygen 1 
Carbonic oxide 1, Chlorine 1 


Hydrochloric acid 2 
AVater vapor 2 
Carbonic anhydride 2 
Phosgen 1 



N. B.—^ln each of the foregoing cases it is necessary to assume 
that the volumes of the combining gases and of the product are 
measured under the same conditions of pressure and of temj^era- 
ture. {See p. 46. ) 

The Atomic Theory. — Certain theoretical conceptions which 
have since developed into what is now called the Atomic Theory, 
were first employed in chemistry by John Dalton, a Manchester 
chemist, in explanation of the regularity which has already been 
mentioned as the Law of Multiple Proportions (p. 51). The most 
important assumptions of this theory are stated in the following 
paragraphs. 

Matter of all kinds is assumed to be composed of extremely 
minute, indivisible particles. These particles have been called 
atoms. Single atoms are so small as to be entirely beyond our 
powers of observation, even with the aid of the most powerful 
magnifying instruments. It is assumed that each element consists 
of atoms of one kind only, the kind, however, being different for 
every element. Every compound, on the other hand, is assumed 
to contain atoms of at least two different kinds — that is, atoms of 
at least two different elements — combined together chemically. 

Estimates have been made as to the probable shape, size, and 
mass of atoms. At best, these must be regarded as approxi- 
mations only. Experimental evidence points to the atoms of 
different elements possessing very different iveights. The absolute 
mass is not known in the case of any atom, but the ratio to each 
other of the weights of the atoms of different elements can be 
determined with accuracy. A series of numbers which represent 
the relative wei<jhtH of the different kinds of atoms has accordingly 
been drawn up. These numbers are relative atomic iveights, and 
are as a rule simi)ly called atomic iveights. They will be discussed 
further on. 

The aggregates of atoms which are produced when two or more 
unlike atoms c()ml)ine together to form the smallest particles of a 



AVOGADRO'S HYPOTHESIS. 53 

compound substance, are called molemd.es. ^ The most simply 
constituted molecule of a compound substance conceivable must 
necessarily consist of at least two unlike atoms. The molecules 
of carbonic oxide are believed to possess this simple constitution, 
and to consist each of one atom of carbon and one atom of oxygen. 
The next simplest conceivable constitution for the molecule of a 
compound is that it should consist of three atoms. In this case 
there are two possibilities: — 

1. All three atoms may be different ; or 

2. Two atoms may be of one kind and one of another. 

The molecules of hydrocyanic acid are regarded as illustrating 
the first of these possibilities, and as consisting each of one atom 
of hydrogen, one of carbon, and one of nitrogen. The molecules 
of carbonic anhydride are regarded as illustrating the second, and 
as consisting each of one atom of carbon and two of oxygen. 
The molecules of many substances are supposed to present much 
greater complexity than these. 

If we now compare carbonic oxide and carbonic anhydride in 
light of the atomic theory, we perceive the character of the ex- 
planation afforded by the theory for the observed facts concerning 
the quantitative relations to each other of the elements which form 
the two compounds (p. 51). Carbonic anhydride contains, for a 
given weight of carbon, exactly twice as much oxygen as carbonic 
oxide does. According to the atomic theory, this is because a 
molecule of carbonic anhydride contains for one atom of carbon, 
two atoms of oxygen, while a molecule of carbonic oxide contains 
for one atom of carbon, only one atom of oxygen, 

Avogadro's Hypothesis. — When the facts which find expression 
in the Law of Gaseous Volumes — referring, as they do, to the 
combination of gases in simple rational proportions by volume to 
form products whose volumes are simply related to those of the 
gases which combine (p. 51) — are considered in connection with 
the idea of combination in simple atomic proportions according to 
Dalton's atomic theory, it becomes evident that there must be a 
simple relation between the volumes which gases occupy and the 
numbers of molecules present in these volumes. The nature of 
the relation is expressed by the Hypothesis of Avogadro, which is 
usually stated as follows: — 

Equal volumes of all gases, under the sam,e conditions of j>irssure 
and of temperature contain the same number of molecules. 

In order to bring this very simple hypothesis into harmony witli 
the observed facts, in all cases of combination of gases witli ench 
other, it is necessary to make the further assumption that even in 
the elementary gases, hydrogen, oxygen, nitrogen, and chlorine. 

^ The word molecule is also applied, as will ai»i>car later, to a.aiivopUos 
consisting of two or more like atoms. A number of elementary gases 
and vapor are supposed to be made up of particles consisting oV such 
groups of like atoms. 



54 GENERAL PRINCIPLE.S OF CHEMICAL PHILOSOPHY. 

the particles do not consist of single atoms, but of pairs of like 
atoms associated together to form molecules. In illustration of 
this matter, the case of the combination of hydrogen with chlorine 
furnishes a good example. One volume of hydrogen combines, 
as we have seen (p. 52), with one volume of chlorine to form two 
volumes of hydrochloric acid gas.^ The volume of the product 
is here double that of either of the constituent gases, and there- 
fore, according to Avogadro's Hypothesis, it contains twice as 
many molecules a^, either of those volumes. But every molecule 
of the resulting hydrochloric acid gas contains both hydrogen and 
chlorine, and, as there are twice as many molecules of it (each 
containing hydrogen and chlorine) as there were of the original hy- 
drogen or of the original chlorine, each molecule of the two latter 
gases must have undergone division into two parts, and must 
therefore have consisted originally of not fewer than two atoms. 
There is evidence from another source that the molecules of the 
elementary gases do not consist of more than two atoms (jd. 58). 

Molecular Weights. — If, as Avogadro's Hypothesis assumes, 
equal volumes of all gases contain, under like conditions, the same 
number of molecules, then the differences in the weights of equal 
volumes of the various gases (as observed in making determinations 
of their relative densities) can only be accounted for by differences 
in the weights of the respective molecules of w^hich the different 
gases consist. Accordingly the determination of the weights of 
equal volumes of different gases (under like conditions) should 
furnish numbers which stand to each other in the ratios of the 
weights of the molecules of the respective gases. But this is the 
determination which is actually made in ascertaining the relative 
densities of gases (p. 48) ; hence the numbers representing the 
relative densities of gases lead directly to the relative weights of 
the molecules of the gases. 

As already stated, hydrogen is adopted as standard, with density 
= 1, for the comparison of the relative densities of other gases 
(p. 48). For the comparison of the relative molecular weights 
of gases hydrogen is also adopted as standard, but with molecular 
weight = 2. Hence, since the relative molecular weight is in all 
gases proportional to the relative density, the relative molecular 
weight of any gas is expressed by a number which is double that 
which expresses its relative density. Thus we have: 

Relative Density. Relative Molecular 
Weight. 
Hydrogen ... 1 2. 

Oxygen .... 15.88 31.76 

Carbonic anhydride . . 21.835 43.67 

Water vapor . . 8.94 17.88 

and so on. The numbers designated relative molecular weights 
above are, as a rule, simply called Molecular Weights. 
'All measured under like conditions of pressure and of temperature. 



ATOMIC WEIGHTS. 55 

There are many substances of which the molecular weights are 
unknown, because they cannot be obtained in the gaseous state, 
and because certain other known methods of molecular weight 
determination cannot be applied to them. 

Gramme Molecule. — For chemical purposes it is often convenient 
to deal with definite quantities of substances in grammes (but of 
course other definite weights could be employed), these quantities 
being based upon the molecular weights of the substances. When 
the number which expresses the molecular weight of any substance 
is considered as representing that same number of grammes, this 
quantity is called the "molecular weight in grammes" of the 
substance, or, more shortly, the gramme molecule. This is an 
important quantity with respect to each substance. (Compare 
pp. 56 and 59.) The gramme molecule of hydrogen weighs two 
grammes. 

Atomic Weights. — If, in accordance with the atomic theory, 
molecules are aggregates of atoms, the weight of any given mole- 
cule must be made up of the separate weights of the atoms which 
compose it, and must, therefore, be equal to the sum of these 
separate weights. Hence, if it is possible to ascertain by any 
means the kinds of atoms, and the number of each kind, which 
go to constitute the molecules of any compound it should like- 
wise be possible to ascertain the relative weights of the atoms of 
each kind from the relative molecular weights of the compounds 
into whose composition they enter. It has, as a matter of fact, 
been found possible to obtain a great deal of information with 
respect to these matters. The means by wHich this information 
is obtained may be stated as follows. 

1. By making use of the ordinary methods of chemical analysis, 
the kinds of atoms present in a compound can be determined ; 
that is, the presence of the particular elements of which it is com- 
posed can be recognized, and the absence of others can be proved. 
By means of methods of quantitative analysis, the quantity of each 
element present in a given compound can be determined. 

2. When the results of quantitative analyses are so tabulated as 
to show the weight of each element which is present in those 
quantities of compound substances which have already been 
described as their gramme molecules, it is found that the 
gramme molecules of different compounds containing one element 
in common, contain quantities of that element which are related 
to each other in a very simple manner. The nature of this simple 
relation is exhibited in the subjoined tables. In e.ach of these 
tables the numbers given in Column 11. represents the weights in 
grammes of the substances named in Column I., which occupy, in 
the gaseous state, and under like conditions of pressure and of 
temperature, the same volume as two grammes of hydrogen. The 
numbers given in (lolumns III. and TV. show the composition, 
by weight, of the quantity of each substance which is set down in 
Column II. 



56 GESERAL PEiyCIPLES OF CHEMICAL PHILOSOPHY. 



1. Hydrogex, and Hydrogen Compounds. 

Names of substances and weights of The weights stated in Column II., of 
them, in grammes, which occupy, in ^he respective substances named in 
i1SSr7b/'t™J"'vSrume"as'' ^o Column I., contain the undernoted 



grammes of hydrogen. 



weights, in grammes, of — 



I. 


II. 


III. 


IV. 


Names. 


Weights 


. Hydrogen. Other Elements. 


Hydrochloric acid . . . 


36.18 


1 


Chlorine . . . 35.18 


Hydrobromic acid . . 


80.36 


1 


Bromine . . . 79.36 


Hvdrogen 


2.00 


2 




Water 


17.88 


2 


Oxvgen .... 15.88 


Hydrogen sulphide . . 
Ammonia 


33.83 
16.93 


2 
.3 


Sidphur . . . .31.83 
Nitrogen . . . 13,93 


Hydrogen phosphide . . 


33.77 


3 


Phosphorus . .30.77 


Mai-sh gas 


15.91 


4 


Carbon .... 11.91 


defiant gas 


27.82 


4 


Carbon .... 23.82 






6 


r Carbon .... 23.82 
\ Oxygen .... 15.88 


Ethyl alcohol 


45.70 






10 


f Carbon .... 47.64 


Ether 


73.52 


\ Oxygen . . . .15.88 


n. Oxygen, and 


Oxygen 


Compounds. 


I. 


II. 


III. 


lA'. 


Names. 


Weights. 


Oxygen. 


other Elements. 


Water 


17.88 


15.88 


Hvdrogen . . 2.00 


Carbonic oxide .... 


27.79 


15.88 


Carbon .... 11.91 


Oxygen 


31.76 


31.76 




Carbonic anhydride . . 


43.67 


31.76 


Carbon .... 11.91 


Sulphurous anhydride 


63.59 


31.76 


Sulphur . . . 31.83 


Sulphuric anhydride . 


79.47 


47.64 


Sulphur . . . 31.83 


Nitric acid 


62.57 


47.64 


J Hvdrogen . . . 1.00 
I Nitrogen . . . 13.93 


in 


. Carbon Compounds. 


I. 




11. 


III. TV. 


Names. 


Weights. 


Carbon. Other Elements. 


Carbonic oxide .... 


. . . 


27.79 


11.91 15.88 


Marsh gas 


. . . 


15.91 


11.91 4.00 


Ethane 


. 


29.82 


23.82 6.00 


Ethyl alcohol .... 




45.70 


23 82 21.88 


Propane 




43.73 
57.64 


35.73 8.00 
d7 as ^o on 


Butane 




IV. Nitrogen, and 


Nitrogen Compounds. 


I. 




II. 


III. IV. 


Names. 


Weights. 


Nitrogen. Other Elements. 


Ammonia 




16.93 
29.81 


13.93 3.00 
1 3 93 1 5 88 


Nitric oxide 




Nitric acid 




62.57 


13.93 48.64 
27.86 


Nitrogen 




27.86 


Nitrous oxide 




43.74 


27.86 15.88 


Cvanogen 




51.68 


27.86 23.82 



ATONIC WEIGHTS. 57 

observed when the numbers which fall into Column III. in each 
table are considered. Thus the quantity of each substance which 
in the state of gas occupies the same volume, under the same con- 
ditions of pressure and of temperature, as 2 grammes of hydrogen 
(Column II.), does not in any case contain a smaller quantity of 
hydrogen than 1 gramme, of oxygen than 15.88 grammes, of car- 
bon than 11.91 grammes, or of nitrogen than 13.93 grammes. 
Further, if the quantity of any compound noted in Column II. 
contains more than 1 gramme of hydrogen, it does not contain 
less than 2 grammes; if more than 2 grammes, not less than 3 
grammes, and so on. Similarly in the case of oxygen compounds, 
if the quantity noted in Column II. contains more than 15.88 
grammes of oxygen, it does not contain less than 31.76 grammes; 
if more than 31.76 grammes, then not less than 47.64 grammes, 
and so on. Regularity of the same simple kind is also observed 
with respect to the carbon and nitrogen compounds. The lists of 
compounds given here are intended to be illustrative only, and 
not exhaustive ; since each table might have been greatly 
extended, and additional tables might have been given, embracing 
compounds of many other elements, when the same kind of regu- 
larity would have appeared throughout. In the case of each 
element, therefore, there appears in Column III. a minimum 
number, and all the numbers in this column for one and the same 
element are either this minimum number or multiples of it. It 
is concluded from the uniformity observed in this respect that the 
minimum number so obtained for each element represents (rela- 
tively to hydrogen assumed = 1) the smallest proportion by 
weight in which that particular element enters into combination — 
that this minimum number is, in short, the atomic weight of the 
element. The atomic theory offers a sufficient explanation of the 
observed facts. In the oxygen compounds, for example, the 
molecular weights of these compounds are made up of the weights 
of the atoms of the other elements present in the molecule besides 
oxygen, and of 1, 2, 3, etc. times the weight of one atom of 
oxygen. From this we conclude that the various molecules con- 
tain 1, 2, 3, etc. atoms of oxygen. It is clear that if a molecule 
contains any oxygen at all, it must contain not less than one atom 
of this element ; if it contains more than one atom, it cannot con- 
tain fewer than two atoms, and so on. Exactly similar consider- 
ations may be applied to the compounds of other elements. 

An examination of the fticts contained in the tables, and of the 
conclusions drawn from them, justifies the view that there are in 
each molecule — 

Of water 1 atom of oxygen and 2 of hydroiion 

" carbonic oxide . . . 1 " " 1 " carbon 

" nitrons 1 '' " 2 " nitrogen 

" ammonia 1 " nitrogen 3 " hydrogen 

" marsh gas 1 " carbon 4 " " 

and so on. 



58 GENERAL PRINCIPLES OF CHEMICAL PHILOSOPHY. 

In the tables referring to the compounds of hydrogen, oxygen, 
and nitrogen, the elements themselves have also been included. 
It will be noticed that the figures for them in Column III. of the 
respective tables are not the minimum numbers which have been 
arrived at as their atomic weights, but are double these numbers. 
From this it is concluded that their molecules must each consist 
of two, and of not more than two, atoms. 

Law of Dulong and Petit, — This law^ states that the product of 
the atomic w^eight and the specific heat of solid elements is a con- 
stant number. This constant is called the atomic heat, and hence 
the law may also be stated thus : — 

The atomic heats of all solid elements are equal. 

The law does not hold quite accurately, the atomic heats of 
solid elements being found to differ from one another to some 
extent. They nearly all approximate moderately closely, how- 
ever, to the number 6.4, A few examples are given below : — 

Atomic Weight X 
Element. Atomic Weight. Specific Heat. Specific Heat 

. (=Atomic Heat). 

Sodium 22.88 .29 6.6 

Iron 55.5 .112 6.2 

Zinc 64.9 .093 6.0 

Tin 118.1 .054 6.4 

Mercury ...... 198.5 .032 6.4 

The determination of the specific heat is sometimes made in 
order to confirm the atomic weight of an element, since the con- 
stant 6.4 H- specific heat should give a quotient approximating to 
the atomic weight. 

Chemical Notation. — A system of notation has been adopted for 
the purpose of shortly and concisely expressing the chief facts 
concerning chemical actions. This system is based upon the 
facts, and the theories deduced from these facts, which have been 
outlined in the preceding pages. The essential features of the 
system are explained in the following paragraphs : 

1. Symbols. — For the purposes of the system, each element has 
had a symbol assigned to it. This symbol is usually the first 
letter, sometimes the first and a succeeding letter, of the English 
or of the Latin name for the element. Thus, H is the symbol 
for hydrogen, Fe (Ferrum) the symbol for iron, and so on. A 
list of the names of the elements, with their symbols and their 
atomic weights will be found at top of page 59. 

For a complete list of the elements, with their symbols and 
atomic weights, see the Appendix. 

The symbol for each element is employed to represent : — 

a. The name of the element. 

b. An atom of the element. 

c. A definite weight, in grammes, of the element. This w^eight 

is the number representing the atomic weight of the 



CHEMICAL NOTATION. 



59 



The Chief Elements mentioned in the United States Pharmacopoeia, 
ivith their Symbols and Atomic Weights. 



Element. 



Aluminium .... 
Antimony (Stibium) 

Arsenic 

Barium 

Bismuth , . , . . 

Boron 

Bromine . .... 

Calcium 

Carbon 

Cerium 

Chlorine 

Chromium .... 
Copper ( Cuprum ) . 
Gold (Aurum) , . 
Hydrogen .... 

Iodine . 

Iron (Ferrum) . . 



Sym- 


Atomic 


bol. 


Weight. 


Al 


26.9 


Sb 


119.3 


As 


74.4 


Ba 


136.4 


Bi 


206.9 


B 


10.9 


Br 


79.3 


Ca 


39.8 


C 


11.91 


Ce 


139.2 


CI 


35.18 


Cr 


51.7 


Cu 


63.1 


Au 


195.7 


H 


1.00 


I 


125.90 


Fe 


55.5 



Element. 



Lead (Plumbum) . 

Lithium 

Magnesium .... 
Manganese .... 
Mercury ( Hydrargy- 
rum) 

Nitrogen 

Oxygen 

Phosphorus . . . 
Platinum .... 
Potassium (Kalium) 
Silver (Argentum) 
Sodium (Natrium) 

Sulphur 

Tin (Stannum) . . 
Zinc 



Sym- 
bol. 



Pb 
Li 
Mg 
Mn 

Hg 

N 

O 

P 

Pt 

K 

Ag 

Na 

S 

Sn 

Zn 



Atomic 
Weight. 



205.35 
6.98 
24.18 
54.6 

198.5 
13.93 
15.88 
30.77 

193.3 
38.86 

107.12 
22.88 
31.83 

118.1 
64.9 



element, taken as grammes; thus the symbol for hydrogen 
represents 1 gramme of hydrogen, because the atomic 
weight of hydrogen is 1; the symbol for iron, 55.5 gram- 
mes of* iron, because the atomic weight of iron is 55.5; 
and so on. 

2. Eormulce. — Symbols are employed in writing formulce. A 
chemical formula usually consists of two or more symbols written 
side by side, as CO, which represents carbonic oxide. 

When two or more atoms of the same kind are to be represented 
in a formula, this is done by writing a small figure to the right 
of and on a somewhat lower level than, the symbol. The figure 
indicates the number of atoms to be represented. Thus, the 
formula CH^ represents a compound containing one atom of carbon 
and four of hydrogen. A small figure similarly placed after a 
portion of a formula which is enclosed within brackets, multiplies 
everything that is so enclosed. Thus, Ba(N03)2 indicates a sub- 
stance in which an atom of barium is combined with twice the 
group NO 3. 

A figure placed in front of a formula refers to the whole 
formula, and shows how many times the quantity represented by 
the formula is to be taken. Thus, 3CH^ stands for three times 
the quantity of marsh gas represented by OH^. 

The formula for a substance represents in all cases: — 

a. The kinds of atoms of which the substance consists. 

6. The ratio of the ntimber of atoms of each kind. 



60 CHEMICAL NOTATION. 

c. A definite weight, in grammes, of the substance. This 

weight is the sum of the atomic weights of the atoms rep- 
resented by the formula, taken as grammes. It is called 
the Jo nil u la weight. 
In the case of gases, and of solids and liquids which can be 

converted into the gaseous state without decomposition, the 

formula further represents: — 

d. The quantity of the substance which has already been 

referred to as the gramme molecule (p. 55). 

e. A definite volume of the substance in the gaseous state. 

This volume is, in the case of each substance, when under 
the same conditions of pressure and of temperature, the 
same as that occupied by two grammes (the gramme mole- 
cule) of hydrogen. It is called the gramme molecule 
volume. When numerical expression is given to it, the 
conditions must be stated, since it varies with variations 
of pressure and of temperature. Under standard con- 
ditions of pressure and of temperature {i.e., 760 Mm. and 
0° C, see p. 47), it measures 22.2 litres. 
3. Deduction of the Formula for a Compound from its Compo- 
sition percent. — The results of quantitative chemical analyses of 
compounds are usually expressed in parts by weight percent, of 
each constituent. From these results an empirical formula can 
be deduced. An empirical formula merely expresses the ratio of 
the number of atoms of each kind in the smallest whole numbers. 
A molecular formula, on the other hand, expresses the number 
of atoms of each kind which a molecule is assumed to contain. 

The rule for the deduction of the simplest formula, is to divide 
the quantity percent, of each element by the atomic weight of 
that element. The quotients stand to each other in the ratio of 
the numbers of atoms present in the compound. Thus, the gas 
ethylene has the following composition j)ercent. : — 

C, 85.62; H, 14.38. 

Dividing by the respective atomic weights, we get:^ — 

85.62- 11.91 = 7.19, and 14.38 -- 1 = 14.38. 

But 7.19 : 14.38 :: 1 : 2 : hence the carbon and hydrogen atoms 
are present in the ratio of 1 : 2, and the empirical formula is 

The molecular weight of ethylene, however, is found by 
experiment to be 27. 82, while the formula CH^ corresponds to 
the molecular weight 13.91; hence the molecular formula must 
be (CH,)^, that is, C^H,. 

N.B. — From the composition percent, alone, the empirical formula 
can be deduced. TJie molecular formula can only be obtained when 
the molecular weight is also known. 



GENERAL PRINCIPLES OF CHEMICAL PHILOSOPHY. 61 

4. Calculation of the Composition percent, of a Substance from its 
Formula. — First add up the formula weight of the substance. 
From, this and the separate weights of the constituents the com- 
position percent, is obtained by simple proportion. Thus, to find 
the composition percent, of carbonic anhydride, CO^: — 

C:= 11.91 
0^= 31.76 (15.88X2) 

43.67 = Formula weight. 
Here 43.67 parts by weight contain 11.91 of carbon. -^ 

11.91 X 100 ^ 

. •. 100 contain -^-^ — = 27. 27. 

Again, 43.67 parts by weight contain 31.76 of oxygen. 

31.76 X 100 
.-. 100 contain -^— = 72.73. 

The composition percent, therefore, is : — 

C := 27.27; O = 72.73. 

5. Equations. — Formulae are employed in writing chemical 
equations. These equations represent the changes which occur 
during chemical actions. Formulee representing the quantity of 
each substance which enters into action are placed on one side, 
and formulae representing the quantity of each product are placed 
on the other side of the sign of equality (=). Between the 
various formulae on each side, signs of addition (+ ) are placed. 
These signs are not used in the same sense as in a mathematical 
equation; and a chemical equation is really only an equation in 
so far that all the materials represented on the one side must be 
accounted for in some form on the other side. 

The chemical change which occurs when zinc is placed in 
dilute sulphuric acid is represented by the equation: — 

Zn + H,SO, = H2 + ZnSO^ 

This equation, besides showing the nature of the rearrangement of 
atoms which takes place, indicates the proportions by weight in 
which the substances interact and the proportions of the products, 
since each symbol and formula has its own quantitative signifi- 
cation. It further indicates the volume of hydrogen which can be 
obtained from the weights of materials represented, since the form- 
ula for a gas represents not only a definite weight, but also a definite 
volume (at a given pressure and temperature) of the gas. Thus, 64. 9 
grammes of zinc and 97.35 grammes of sulphuric acid yield 2 
grammes of hydrogen and 160. 25 grammes of zinc sulphate. The 
2 grammes of hydrogen occupy 22. 2 litres at 0°Q'''^ and 760 Mm. 
From such equations, calculations are readily made of the 
quantities of substances by weight or by volume obtainable from 
given quantities of materials. 



62 GESERAL PEIXCIPLES OF CHEMICAL PHILOSOPHY. 

Instead of writing formal equations to represent chemical 
actions, the student will often find it helpful and instructive to 
draw diagrams of a kind which show equally well the original 
form in which the various elements are brought into reaction, and 
the destination of the different atoms. For example, instead of 
writing the equation given above, the liberation of hydrogen by 
the interaction of zinc and dilute sulphuric acid can be sufficiently 
represented for most purposes by writing the formula? for zinc and 
sulphuric acid either in the same line or one above the other, to 
show what substances interact, and then drawing a line to enclose 
the SO^ of the sulphuric acid formula along with the Zn, and 
leaving the H^ of the sulphuric acid formula outside, thus: — 



H^^SO, Zn; or ^ S^ \ 

: i H^i J"^ i 

If the interaction of zinc with hydrochloric acid is to be repre- 
sented, the diagram can be constructed thus: — 



HCl „ ; 

HiCl \ 

The construction of such diagrams is particularly useful in aiding 
the student to obtain an insight into numerous complicated inter- 
actions. Other examples will be given further on. 

Equivalents {Vakncij). — Those quantities of different elements 
which are capable of playing the same part in chemical combina- 
tion, are said to be equivalent to each other. For comparison of 
the equivalent weights of different elements, it is convenient to 
adopt a standard, and the standard chosen is 1 part by weight of 
hydrogen. The equivalent weights — or shortly, the equivalents — 
of other elements are capable of taking the place in combination 
of 1 part by weight of hydrogen (and frequently, moreover, of 
combining with the same weights of other elements that 1 part by 
weight of hydrogen combines with ). Thus, in potassium chloride, 
KCl, 38. 86 parts by weight of potassium take the place of the 1 
part by weight of hydrogen contained in hydrochloric acid, HCl, 
hence the equivalent of potassium is 88.86. In calcium sulphate, 
CaSO^, 39.8 parts by weight of calcium take the place of the 2 
parts by weight of hydrogen contained in sulphuric acid, H,SO^, 

oq g 
hence the equivalent of calcium is !^ =19.9. In bismuth 

nitrate, Bi(X03)3, 206.9 parts by weight of bismuth take the 

place of 3 parts by weight of hvdrogen in three molecules of nitric 

206.9 
acid, 3HXO3, hence the equivalent is — ~— = 68.966, and so on. 

3 



EQUIVALENTS. 63 

The number expressing the equivalent weight is thus sometimes 
the same as the atomic weight, sometimes it is one-half the atomic 
weight, sometimes one-third, and so on. In other words, an atom 
of another element may be capable of taking the place of (or 
of combining with): — (a) one atom of hydrogen (an atom of potas- 
sium, for example); (6) two atoms of hydrogen (an atom of calcium, 
for example) ; (c) three atoms of hydrogen (an atom of bismuth, for 
example) ; and so on. The power possessed by the atoms of other 
elements, of replacing or of combining with different numbers of 
hydrogen atoms, has been called the atomicity, or combining capac- 
ity or quantivalence, or, perhaps more commonly, the valency of 
the elements. 

The number representing the valency of an element may be 
ascertained by observing the number of hydrogen atoms which it 
is capable of replacing, or with which it is capable of combining ; 
also, by observing, for example, the number of atoms of chlorine 
with which it is capable of combining — each atom of chlorine 
being regarded as of the same valency as hydrogen, because each 
atom of chlorine combines with one atom of hydrogen. 

For example, potassium (K), calcium (Ca), bismuth (Bi), and 
carbon (C), are regarded as univalent, bivalent, trivaleni and quad- 
rivalent, respectively, because they form chlorine compounds 
represented by the formulae KCl, CaClg, BiClg, CCl^. In the 
case of carbon, CH^ is also known. 

With respect to the terms equivalent and valency, it is to be 
noted that they are applicable to radicals ^ as well as to atoms. 
Thus, in calcium sulphate, CaSO^, the radical SO^ is equivalent 
to (NO 3) 2 in calcium nitrate, Ca(]S'03)2, or to G\ in calcium 
chloride, CaCl2, since it is capable of combining with the same 
thing, i.e., with one atom of calcium. SO4 is a bivalent radical, 
while both NO 3 and CI are univalent. 

It is sometimes convenient to indicate the valency of a metallic 
radical by placing after it an appropriate number of dots, thus: 
Mg--; and similarly the valency of an acid radical may be indi- 
cated by an appropriate number of dashes, thus: PO/^^. 

Bases, Acids, and Salts. — In order to give the student some 
familiarity with these classes of chemical substances, and so to 
prepare him the better to understand the use of the words base, 
acid, salt, and the frequent references to these substances in the 
immediately succeeding portions of this Manual, it is desirable, 
before concluding the discussion of the general principles of 
chemistry, to make some general statements regarding these im- 
portant groups. 

Bases. — There are two principal classes of compounds which 

^ The name radical is very often used in chemistry to desiijnate a group 
of atoms which is common to a number of compounds, and is oapablo of 
being transferred from one compound to jiuother without itself breaking 
up. 



I 



64 GENERAL PRINCIPLES OF CHEMICAL PHILOSOPHY. 

behave as bases, and possess in a more or less marked degree the 
properties of these substances, as described further on. These 
two classes embrace : — 

1. The basic oxides and hydroxides of the metals. Examples — 

Calcium oxide (quicklime) CaO; calcium hydroxide (slaked 
lime) Ca(0H)2; aluminium hydroxide A1(0H)3; ferric 
oxide FCgOg, etc. 

2. Ammonia, NHg, and the substituted ammonias (such as 

methylamine, NHjCHg ; dimethylamine, NH(CH3)2 ; 
aniline, NH^CgH^, etc.); also a large number of allied sub- 
stances, including the natural alkaloids (such as morphine 
C„H,,N03, H/); strychnine C^.H^^N^O^, etc. 
There are grounds for supposing that all substances which 
exhibit the characters of bases are hydroxides, and that those 
compounds belonging to the above two classes which are not 
hydroxides to begin with, must interact with water, so as to yield 
hydroxides before their capacity to behave as bases is developed. 
Thus, it is probable that quicklime is not itself a base, but that 
the actual base is slaked lime (calcium hydroxide), which is 
formed by the interaction of quicklime with water: — 

CaO + H^O = Ca(0H)2 ; 

and that ammonia only attains basic properties when it has inter- 
acted with water to form ammonium hydroxide— 

NH3 + H^O = NHpH. 

Properties of Bases. — Those bases which dissolve easily in water 
yield solutions possessing an alkaline reaction, that is, their solu- 
tions exhibit the property possessed by solutions of the alkalies 
(potassium hydroxide, KOH, and sodium hydroxide, NaOH, 
which are themselves basic hydroxides, see pages 72 and 86) of 
turning red litmus paper blue, -of browning yellow turmeric 
paper, etc. Solutions of some of the most easily soluble bases, 
such as potassium and sodium hydroxides, possess an unpleasant 
taste, resembling that of soapy water. (As a matter of fact, the 
taste of soapy water is chiefly due to the presence of one or other 
of these hydroxides in small quantity.) 

Bases interact with acids to form salts. This statement is true 
generally, but it requires qualification in so far that there are 
some bases which (usually on account of their insoluble character) 
are not acted upon by certain acids. When bases interact with 
acids, the formation of salts is accompanied by the formation of 
water: — 

Ca(()H)., + 2HCL = CaCl^ + 2YLp ; 
2A1(0H )3 + 3H,S0, =-- A1,(S0J3 + 6H,0 ; 
NH.OH + HCl = NH.Cl + H^O ; 



BASES, ACIDS, SALTS. 65 

Acids. — Three important classes of acids may be distinguished. 
These classes do not exhibit many prominent differences in char- 
acter, although they differ considerably in their general chemical 
relations. The three classes are : — 

1. Acids which may be regarded as derived from acid oxides 

or acid anhydrides, by the action of water. Thus sul- 
phuric anhydride when treated with water yields sulphuric 
acid : — 

SO 3 + H^O = H^SO, 

(The majority of the more important acid anhydrides are, 
as the student will learn later, oxides of non-metallic 
elements. ) All the acids belonging to this class contain 
oxygen. 

2. Acids which do not contain any oxygen in their compo- 

sition. The best examples are the halogen acids — hydro- 
chloric acid, HCl ; hydrobromic acid, HBr ; hydriodic 
acid, HI ; and hydrofluoric acid, HF. 

3. A large number of organic acids, all containing carbon, 

hydrogen, and oxygen, either along with, or without other 
elements. Examples — Oxalic acid, H2C20^; acetic acid, 
H4C2O2; benzoic acid, HgC^Og; chloracetic acid, H3C2O2CI, 
etc. 

Properties of Acids. — The majority of acids dissolve readily in 
water. The aqueous solutions in most cases possess the acid 
reaction, that is, they redden blue litmus paper. They also 
possess a characteristic sour taste, as in the familiar cases of 
tartaric acid (the acid of unripe grapes), acetic acid (the acid 
present in vinegar), etc. 

All acids contain hydrogen as an essential constituent. This 
hydrogen is replaceable, in some cases wholly, in some only 
partially, by metals, or by groups of atoms (radicals) which play 
the part of metals. The substances produced by such replace- 
ment are called salts. They are formed, as has already been 
stated, by the interaction of bases and acids, with the simul- 
taneous production of water. 

Salts. — Salts are compounds which may all be regarded as 
made up of metal, or of a radical which plays the part of metal 
— such metal or radical forming the metallic or basic radical — 
united to an atom, or group of atoms, which constitutes the acid 
radical. The metallic radical of the salt takes the place of the 
hydrogen of the acid, or of a part of it : the acid radical of the 
salt is common both to the salt and to the acid from which it is 
derived. In a sense, the acids are themselves salts. They 
closely resemble salts in several particulars, and they are fre- 
quently called hydrogen salts. 

Salts are produced in various other ways, as well as by the 
interaction of bases and acids. A common instance of this is 



Q6 GENERAL PRiyClPLES OF CHEMICAL PHILOSOPHY. 

seen in the formation of salts by the interaction of metals and 
acids, ^^hns the best way to prej^are silver nitrate is to treat 
silver with nitric acid. 

The following classes of salts are distinguished : — 

Xeidral Salts. — These salts when dissolved in water yield 
solutions which show neither the acid nor the alkaline reaction. 
Examples of neutral salts — Sodium chloride, XaCl; potassium 
sulphate, KgSO^; etc. 

Xormal /Salts. — This name is applied to salts w^hich are formed 
when the whole of the replaceable hydrogen of an acid is rei:)laced 
by a metal. Normal salts are frequently neutral also, but they 
are not necessarily so. Examples of normal salts — Potassium 
sulphate, K.,vSO^ ; sodium carbonate, Na2C03. 

Acid Salts. — Salts which contain some of the replaceable hy- 
drogen of the original acid unreplaced by metal, are called acid 
salts. They are intermediate in composition between the acid 
and the normal salt. Thus potassium hydrogen sulphate, KHSO^ 
(an acid salt), is intermediate between sulphuric acid, H^SO^, 
and normal potassium sulphate, K^SO^. Acid salts possess the 
acid character, in so fVir that they still contain hydrogen of the 
original acid, which is replaceable by metal to form a normal salt. 
They do not, however, necessarily show the acid reaction with litmus. 

Basic Salts. — Salts which are intermediate in composition between 
basic oxide or hydroxide and normal salt, are called basic salts. 
Thus bismuth oxychloride, BiOCl (a basic salt), is intermediate 
between basic bismuth oxide, Bi^Og, and normal bismuth chloride, 
BiClg. Basic salts possess the basic character, in so far that 
they still contain oxygen of the basic oxide, or hydroxyl (OH) of 
the basic hydroxide, Avhich is replaceable by an acid radical to 
form a normal salt. A large number of basic salts are insoluble 
in water, and cannot therefore show any reaction with litmus. 

Basiciti/ of Acids, and Acidity of Basses. — Acids are called 
monobasic, dibasic, tribasic, etc., according as they contain in 
their molecules one, two, three, etc., hydrogen atoms displaceable 
by metals. Polybasic acids contain several displaceable hydrogen 
atoms. Bases are called mono-acid, di-acid, tri-acid, etc., accord- 
ing as the acid radical from one, two, three, etc., molecules of a 
monobasic acid enters into the coiiiposition of the normal salts 
derived from them. 

Equations illustrating basicity of acids : — 

HNO3+ KOH =KXO„ +H2O 
H.SO^ + 2K0H = K.,SO'^ + 2H2O 
H3PO4 + 3K()H = K;p04 + SHp 
Equations illustrating acidity of bases : — 
KOH +^ HCl = KCl + H^O 
Ca(0H)2 + 2HC1 = CaCl, + 211 f> 
Bi(0H)3 + 3HC1 = BiCla + 3H„0 



ELECTROLYSIS. 67 

Electrohjsis. — When a current of electricity is passed through 
a dilute solution of sulphuric acid, by introducing into the 
solution electrodes (which may consist conveniently of strips of 
platinum foil) connected with the wires leading from a sufficiently 
powerful battery, hydrogen is given oif at the electrode connected 
wdth the negative pole of the battery, and oxygen at that con- 
nected with the positive pole. These gases are given off in the 
proportions in which they combine to form water, and the exper- 
iment at first sight appears to be, and is sometimes simply called, 
the electrolysis (that is, the decomposition by a current of elec- 
tricity) of water. The sulphuric acid, however, although its 
quantity remains the same at the end of the experiment as it was 
at the beginning, obviously plays an important part in the process, 
because in its absence scarcely any current passes, and corres- 
pondingly little water is decomposed. The nature of the chem- 
ical change which takes place may be represented as, in the first 
place, the liberation, from the acid, of hydrogen at the one 
electrode and of the acid radical — the group SO^ — at the other. 
But the acid radical (SO^) is unknown as a separate substance, 
and is probably incapable of existence as such; hence, at the 
moment of its liberation, it interacts with water of the solution, 
taking its hydrogen to form sulphuric acid again, and liberating 
its oxygen. These changes may be illustrated diagrammatically 
as follows : — 

(a) As the first result of electrolysis, HgSO^ yields : — 
At the negative electrode. 



At the positive electrode. 

[SO J 
{b) Further change : 
[SOJ and H2O- give H2SO4 and O^ 



Accordingly, the final result of the change is that water mole- 
cules are, by this indirect means, decomposed into hydrogen 
and oxygen, while the sulphuric acid remains in undiminished 
quantity at the end of the experiment. 

A case nearly analogous with the preceding one is that of the 
electrolysis of a solution of sodium sulphate. In this case also, 
hydrogen and oxygen are given off in the proportions in which 

1 Single atoms of hydrogen and of oxygen liberated in this way at the 
respective electrodes unite with each other in pairs to form molecules 
of gaseous hydrogen, H2, and oxygen, O2 (or the oxygen atoms may to 
some extent unite in grou^js of three to form molecules of ozone, O;) ; 
[see Index]. 

'^ The group [SO4] may also he regarded as interacting with two water 
molecules to form H^SOi and two [OH] groups, which latter are then 
supposed to interact, with the formation of water and oxygen: 



[80.] + gOH ^ jj,^,o^ ^ |-OHJ ^ ^„„ J-OHJ ^ H, 



o + o 



68 GENERAL PEIXCIPLES OF CHEMICAL PHILOSOPHY. 

tlioy are present in water. It may be represented that the sodium 
sulphate is first separated into sodium and the acid radical of the 
sulphates, NagSO^ yielding : 

At the negative electrode. I At the positive electrode. 

Na Na | [SOJ 

But in this instance the sodium as well as the acid radical enters 
into a new reaction with water of the solution and the following 
further chano;es occur : 



2Na and 2H2O give 
2NaOH and H^. 



[SO4] and H2O give 
H2SO4 and O. 



In light of the foregoing mode of representing the electrolysis 
of sodium sulphate, it would appear that sodium hydroxide is 
produced at the negative pole in addition to the hydrogen; and 
that sulphuric acid is produced at the positive pole in addition to 
the oxygen. This is indeed found to be the case, and may easily 
be demonstrated by testing the liquid in the immediate neighbor- 
hood of the two electrodes, by means of litmus papers, during 
the passage of the current. Whilst the sodium sulphate solution 
is itself neatral, the liquid at the negative pole is found to be 
alkaline, and that at the positive pole is found to be acid. It is 
to be noted, moreover, that the quantity of sodium hydroxide 
formed at the negative electrode is exactly the quantity required to 
interact with the whole of the suljDhuric acid formed at the posi- 
tive electrode, to form sodium sulphate again (neutral solution) 
in accordance w^ith the equation, 

2XaOH + H^SO, = Na^SO, + 2TLfi 

so that when the solution is thoroughly mixed up sodium sul- 
phate is present in it in undiminished quantity. 

Other salts in aqueous solution (or in the fused state if they 
stand fusion without undergoing decomposition) can also be elec- 
trolyzed. The metal of the salt, or that which plays the part of 
metal, is separated at the negative electrode, and the acid radical 
at the positive electrode. Substances which are capable of decom- 
position by electrolysis are called electrolytes. When the first 
products of the electrolysis are capable of existence in the con- 
ditions under which they are produced, then these are the 
products obtained. Secondary changes are, however, of frequent 
occurrence, as in the foregoing illustrations. 

^ . In regard to their electrolysis, the acids (hydrogen salts) behave 
in a manner exactly analogous with the behavior of other salts. 

The positive electrode is often called the anode, and the nega- 
tive electrode the cathode {ava, ana, upward; Kara, kata, down- 
ward; ofior, hodos, way). Metals and hydrogen are set free at the 
cathode, and acid radicals and oxygen at the anode. 

It has been found that the quantity of an electrolyte which 



ELECTROLYSIS. 69 

undergoes decomposition by electrolysis is directly proportional to 
the amount of current passed through it. Further, it has been 
found that the quantities of hydrogen, and the quantities of 
oxygen liberated in a given time from dilute solutions of sulphuric 
acid, of sodium sulphate, and of potassium sulj)hate, when the 
current is passed simultaneously through all three solutions, are 
the same for each solution. Similarly the quantities of copper 
separated from two or more different cupric salts under like con- 
ditions are identical: and the same kind of regularity holds good 
for other metals and acid radicals. 

In recent years electrolytic methods have been extensively 
introduced for the technical production of chemical compounds, 
for the separation of metals, etc. References to the preparation 
of a number of substances by these methods, are made in various 
places in this Manual. See, for example, under jDotassium chlor- 
ate, sodium by hydroxide, iodoform, aluminium, sodium, etc. 

Oxygen and hydrogen, when liberated from combination in 
immediate contact with substances with which they are capable 
of interacting to yield products of oxidation and reduction (reduc- 
tion =deoxidation or removal of oxygen), are found to be much 
more active towards these substances than they are if prepared in 
separate vessels and subsequently brought into contact with them. 
The special activity of such nascent {i.e., newly formed) oxygen 
and hydrogen, has been attributed to the action of atoms of these 
elements, which enter into other reactions without combining in 
pairs to form oxygen and hydrogen molecules. Various electro- 
lytic and other oxidations, reductions, etc. , are apparently due to 
the action of nascent oxygen, nascent hydrogen, nascent chlorine, 
etc. In a number of cases in later parts of the Manual, where 
equations are given in which the action of nascent hydrogen, etc. , 
is represented, the atomic symbols, H, O, etc. , are used instead of 



The student is recommended to read the foregoing paragraphs on 
the General principles of Chemical Philosophy carefully once or 
twice, then to study {experimentally, if possible) the folhwing pages, 
returning to and reading over the General Principles from time to 
time, until they are thoroughly comprehended. 



QUESTIONS AND EXERCISES. 

What do you understand by chemical changes? — Give examples of 
chemical and physical changes. — Mention some of the chief phenomena 
which accompany typical cases of chemical change. — Wliat is the dif- 
ference between an element and a compound ? — Wliat do you understand 
by the term "chemical affinity "?— Name the chief hnvs of chemical 
combination. — State the law of constant proportions. — State the law of 
multiple proportions.— State the law of gaseous vohnnes.— Give an out- 
line of the atomic theory, exjilaining what is understood by the terms 



^ 



70 THE ELEMENTS AND THEIR COMPOUNDS. 

"atom" and "molecule." — What is Avogadro's hypothesis? — Explain 
why hydrogen molecules are assumed to consist of two hydrogen atoms 
each. — What relation exists between the relative densities and the mole- 
cular weights of gases? — What is the "gramme molecule"? — Explain 
how Avogadro's hypothesis may be applied in the fixing of atomic 
weights. — State the law of Dulong and Petit, and explain how it may be 
of service in fixing atomic weights. — Enumerate the functions of a chem- 
ical symbol and of a chemical formula. — Write equations representing 
the formation of hydrogen by the interaction of zinc w^ith hydrochloric 
acid and with sulphuric acid. — Mention the characters of bases and acids, 
and describe the general nature of the interaction of bases and acids in 
forming salts. — What are neutral salts, normal salts, acid salts, basic 
salts? — Give examples. — Define electrolysis, electrolyte, electrode. — 
What do you understand by "nascent" hydrogen? — Name some impor- 
tant substances which are now prepared on the manufacturing scale by 
electrolytic methods. 



THE ELEMENTS AND THEIR COMPOUNDS. 

Having thus obtained a general idea of the nature of some of 
the non-metallic elements which have sj^ecial interest for the med- 
ical and pharmaceutical student, and of the fundamental }3rinci- 
ples of chemistry, we may pass on to consider in detail the rela- 
tions of the elements, both non-metallic and metallic, to each 
other. The elements themselves, in the free condition, are sel- 
dom used in medicine, being nearly always in combination — 
bound together by the force of chemical atfinity; in this combined 
condition, therefore, they must be studied, inorganic combinations 
first, organic afterwards. Most compounds met within the mineral 
kingdom may be regarded as containing two parts or radicals : — 
the one usually metallic; the other commonly a non-metallic, 
simple or complex, acid radical. In the following pages the 
metallic radicals will be considered first, the acid radicals after- 
ward. Each radical wall be studied from two points of view, 
the .synthetical and the analytical ; that is to say, the properties of 
an element on which the preparations of its compounds depends 
will be illustrated by discriptions of actual experiments, and thus 
a knowledge of the principles of chemistry and of their applica- 
tions to medicine and pharmacy be acquired; then the reactions 
by which the element is detected, though combined by other sub- 
stances, will be performed, and so the student will be instructed 
in qualitative analysis. Synthetical and analytical reactions are, 
in truth, frequently identical, the object with which they are per- 
formed giving them synthetical interest on the one hand, or 
analytical interest on the other. 

A good knowledge of chemistry nuiy be acquired synthetically 
by preparing considerable quantities of the salts of the different 
metals, or analytically by going through a course of pure quali- 
tative analysis. But the former plan demands a larger expendi- 
ture of time than most students have to spare, while under the 



POTASSIUM. 71 

latter system pupils generally lose sight of the synthetical impor- 
tance which attaches to analytical reactions. Hence the more 
useful system, now offered, of studying each metal, etc. , from both 
points of view, time being economized by the operator preparing 
only small specimens of compounds. 



]\^ofe. — As a general rule, throughout this Manual, paragraphs 
describing experiments to be performed are distinguished from 
paragraphs containing matter merely to be read, by being printed 
in somewhat larger type. 



THE METALLIC EADICALS. 



POTASSIUM : K. Atomic weight, 38.88. 

Occurrence, etc. — The chief sources of the potassium salts are 
the chloride found at Stassfurt, in Prussia, combined with mag- 
nesium chloride in the mineral Caraallite, KCl,MgCl,^,6H20 and 
with magnesium sulphate in Kainite, KCljMgSo^, 3H2O; the 
nitrate found in soils, especially in warm countries; and the com- 
pounds of potassium existing in plants. The potassium salts 
present in plants are converted chiefly into carbonate when the 
wood or other parts are burnt to ashes. If the ashes be lixivi- 
ated with water, and the solution evaporated to dryness, the 
residue when fused constitutes crude potmhes. The residue cal- 
cined on the hearth of a reverberatory furnace till white, gives 
the product termed pearlash, which is impure potassium car- 
bonate. Large quantities of potassium carbonate are thus pro- 
duced in North America and Russia, and, latterly, from the 
sugar beet-root marc, in France. Nearly all other potassium 
compounds are made from the native chloride, or from the car- 
bonate which has been purified by treating pearlash with its own 
weight of distilled water, filtering, and evaporating the solution 
so formed just to dryness, while it is kept briskly agitated. Ex- 
ceptions occur in potassium nitrate, and in cream of tartar 
(Potassii Bltartras, U. S. P.), which is the more or less purified 
natural potassium salt of the grape vine. Potassium, in the 
form of one or other of its compounds, is a constituent of over 
fifty chemical or galenical preparations of the Pharmacopa?ia. 

Preparation. — Potassium itself is isolated by distilling a mixture 
of potassium carbonate and charcoal at a very high temperature, 
or by Castner's method {see Sodium). It rapidly umlergin^s 
oxidation in the air, hence is usually kept below the surface of 
mineral naphtha which protects it from oxidation. It crystal- 
lizes in octahedra. 



v/ 



72 THE METALLIC RADICALS, 

Potassium carbonate {Potassii Carbonas, U. S. P.), is a white 
crystalline or granular powder, insoluble in alcohol but very 
soluble in water yielding a solution which is alkaline and caustic 
to the taste. It rapidly liquefies in the air through absorption of 
moisture. It loses all water at a red heat. 

Potassium Hydroxide. Caustic Potash. 

Experiment 1. — Boil together for a few minutes, in a basin, 
ten to twenty grains of potassium carbonate, K^CO.^, and a 
like quantity of calcium hydroxide (slaked lime), Ca(0H)2, 
with a small quantity of water. Set the mixture aside in a 
closed vessel till all solid matter has subsided. 

The clear liquid is a solution of potassium hydroxide or caustic 
potash, KOH. Made of a prescribed concentration (about 5 per- 
cent.) it forms Liquor Potassii Hydroxidi, U. S. P. 

The mixture is known to haye been boiled long enough when 
a little of the clear liquid, poured into a test-tube and warmed, 
giyes no etferyescence on the addition of an acid (sulphuric, 
hydrochloric, or acetic) — a test the mode of action of which will 
be explained hereafter. 

Solid Caustic Potash. — Solution of caustic potash evaporated to 
dryness in a silver or clean iron vessel, and the residue fused and 
poured into moulds, constitutes caustic potash [Potassii Hydro.vi- 
dum U. S. P). It often contains chlorides, detected by means of 
silver nitrate; and sulphates, detected by means of a barium 
salt ; as described subsequently in connection with hydrochloric 
and sulphuric acids. 

Representing Chemical Changes by means of Equations and Dia- 
grams. — It is desirable that the student should endeavour to 
represent each chemical change that comes under his notice by 
means of an. equation or diagram. The mode of constructing 
such equations and diagrams has been explained already, and the 
student is aware that the chief data required for their construction 
are the formulae of the various substances which enter into and 
are produced by the particular changes under consideration. 
Thus, solution of potassium carbonate and calcium hydroxide 
interact when boiled together to produce calcium carbonate and 
potassium hydroxide. It is necessary to know the formulae for 
all these substances before an equation or diagram can be con- 
structed to represent the interaction. The required formulae are 
respectively, K,CO„ Ca(OH),, CaCO,, and KOH. A few mo- 
ments' reflection should enable the student to perceive that in 
order that CaCo, may be built up from Ca(0H)2 and K2CO3, the 
latter of these two must give up K2 while the former must give 
up (OH).^; and, further, in order that the K2 and the (OH) 2 may 
be conceived as forming a substance having the formula KOH, it 



\ OH 


K 




; OH 


K : 



POTASSIUM. 73 

must be supposed that these materials unite to form two KOH 
groups. 

A diagram representing the change can then be constructed 
easily thus : — 



CO3 



or an equation written thus : — 

Ca(0H)2 + K2CO3 = CaCOs + 2K0H 

The interaction represented by the above diagram and equation 
is an instance of that kind of chemical change commonly called 
double decomposition, the two metallic radicals exchanging places. 
The name metathesis (jue-a, meta, beyond, and diaig thesis, a 
placing) is sometimes given to interactions of this description. 

At the same time that the student is constructing these dia- 
grams and equations for himself, he will carefully bear in mind 
that each formula stands for a definite quantity of the substance 
which it represents; and that, by adding up the quantities thus 
indicated by the formulae constituting an equation, he can readily 
ascertain the proportions by weight in which the substances 
interact and result from interaction. 

Sulphurated Potash. 
Experiment 2. — Into a test-tube put a few grains of a 
mixture of previously dried potassium carbonate and half its 
weight of sulphur. Heat the mixture gradually until it no 
longer effervesces. The resulting fused mass poured on a 
slab and quickly bottled is sulphurated potash. 



SK.COs + 48., = 


-- K^S^Os + 2K,S3 + 


SCO., 


Potassium Sulphur 


Potassium Potassium 


Carbonic 


carbonate 


thiosulphate trisulphide 


anhydride 



As met with in pharmacy, this substance is not a single definite 
chemical compound, but a mixture of several ; in short, its 
chemical character is well indicated by its vague name. When 
fresh, and if carefully prepared with dry ingredients, it is of the 
color of liver (whence the old name "liver of sulphur"), and 
consists, as shown by J. Watts, of the salts mentioned in the 
foregoing equation, together with a little undecomposed potas- 
sium carbonate, with perhaps higher potassium sulphides (K0S4 
and K2S5). By rapidly absorbing oxygen from the air, it soon 
becomes green and yellow, potassium sul})hite, K.80.,, and sulphite 
KoSO^, being successively formed, and ultimately a useless mass of 
a dirty white color results, consisting of potassium sulphate and 



74 



THE METALLIC RADICALS. 



thiosulphate, with generally some carbonate and free sulphur. 
Moreover, if overheated in manufacture, the potassium thiosulphate 
is decomposed into sulphate and pentasulphide (4K2S2O3 = 3K2SO4 
-h K2S5). About fifty percent, of the freshly-made preparation 
should be soluble in alcohol (90 percent.). It is occasionally 
employed in the form of ointment. 

The complicated nature of the interactions that take place in 
this experiment will probably cause failure in any attempt by the 
student to rejiresent these by means of a diagram without, the aid 
of the printed equation already given. He may therefore content 
himself, in this case, by introducing into his note-book a diagram 
founded directly on the equation, and on the numbers of mole- 
cules there stated. 

In preparing large quantities of sulphurated potash, the 
test-tube is replaced by an earthenware crucible (possibly 
from crux, a cross, for originally a cross was impressed upon 
the melting-pot used by alchemists and goldsmiths : others 
derive the word from crux, an instrument of torture, the 
sense here being symbolical). 

Fig. 16. 




Crucibles of various forms. 

Heating cmcibles. — Crucibles of a few ounces capacity may be 
heated in an ordinary fire. Larger ones require a furnace. Even 
the smaller ones are more conveniently and quickly heated in a 
furnace. Half-ounce or one-ounce experimental porcelain crucibles 
may be heated in a spirit or gas-flame, the flame of the Bunsen 
burner already described being generally the most suitable. 

Potassium Acetate. 

Experiment 3. — Place twenty grains or so of potassium car- 
lionate in a small porcelain dish, and saturate (satur, full) 
with acetic acid ; that is, add acetic acid as long as efferves- 
cence is produced; the resulting liquid is a. slight acid solu- 
tion of jiotassium acetate. Boil off most of the water in an 
open dish (See Figs. 17 and 18), stirring with a glass 



1 



POTASSIUM. 



75 



rod ^ to assist the escape of water vapor, and thereby prevent 
spurting ; a white salt remains, which fuses on the further 
careful application of heat : this is the official potassium 
acetate (Potassii Acetas U. S. P.). If fused in an open 

Fig. 17. Fig. 18. 





Evaporation from small and large basins. 

vessel, the acetate is liable to become slightly charred and 
discolored ; this is prevented by transferring the solid residue 
to a test-tube or flask before finally fusing. Potassium 
acetate forms a white deliquescent foliaceous satiny mass, 
neutral to test-paper, and wholly soluble in alcohol. 

+ H,0 +. CO, 

Water Carbonic 
anhydride 

formula for acetic acid (hyd- 

that for potassium acetate, 

is common 



K,C03 + 


2HC,H30, = 


= 2KC2H3O2 


Potassium 


Acetic 


Potassium 


carbonate 


acid 


acetate 



Explaiiation of formulce. — The 
rogen acetate) is HC2H3O2, and 
KC2H3O2. The univalent group or radical, C2H3O2 



to all acetates. A more extended formula for potassium acetate, 
indicating the possible arrangement of the atoms in the molecule, 
isCHg.COOK. 

Diagram of the reaction. — The nature of the above operation is 
indicated by an equation ; it (and succeeding reactions) may be 
expressed in the student' s note-book i{s a diagram, and, if possible, 
without the aid of the above equation. 

Note. — The foregoing reaction has a general as well as a 
special interest. It represents one of the commonest methods of 
forming salts, namely, the decomposition of a carbonate by inter- 
action with an acid. Carbonates added to acetic acid yield 
acetates, to nitric acid nitrates, to sulphuric acid sub)liates. 
Many illustrations of this general })roeess occur in })harinacy. 

^ Glass rod is usually purchased in lenofhs of 5 or (> feet. Those tuny he 
cut into convenient pieces of from 6 to 1"2 inch(>s lonji' (.■^cc p. '2\), shar]i ends 
being rounded ott' by hohling the extremities in a flame for a few minutes. 



il 



76 THE METALLIC RADICALS. 

Evaporation of water from a liquid is best conducted in wide 
shallow vessels rather than in narrow deep ones, as the steam can 
thus quickly diffuse into the air and rapidly be conveyed away; 
hence a small round-bottomed basin, heated as shown in Fig, 17, 
is far more suitable than a test-tube for such operations. On the 
manufacturing scale, iron, or iron lined with enamel, or semi- 
porcelain, copper, tinned copper, or solid tin pans are used. Up 
to 12 or 18 inches diameter, porcelain dishes may be employed. 
Small dishes may be supported by retort stands (Fig. 17), larger 
by cylinders (Fig. 18), to which the dish is, if less in diameter 
than the cylinder, adapted by such flat rings or diaphragms as are 
shown in the figure on page 75. 

Potassium Bicarbonate. Potassium Hydrogen Carbonate. 

Experiment 4. — Make a concentrated solution of potassium 
carbonate by heating in a test-tube a mixture of several 
grains of the salt with rather less than an equal weight of 
water. Through the cool solution pass carbonic anhydride, 
slowly but continuously; after a time a white crystalline pre- 
cipitate of potassium hydrogen carbonate, or potassium bicar- 
bonate, KHCO3 (Fotassii Bicarbonas, U. S. P.), will be 
formed. 



K,CO, + 


H.,0 


+ CO, = 


2KHCO3 


Potassium 


Water 


Carbonic 


Potassium 


carbonate 




anhydride 


bicarbonate 



Generate the carbonic anhydride by adding hydrochloric 
acid, diluted with twice its bulk of water, to a few fragments 
of marble or other carbonate contained in a test-tube or 
small flask, and conduct the gas into the solution of potas- 
sium carbonate through a glass tube, bent to a convenient 
shape and fitted to the test-tube or flask by means of a cork 
in the usual way (see Fig. 10, p. 34), though no heat is neces- 
sary. The tube may be replenished with marble or acid, 
or both, when the evolution of gas is becoming slow. In 
working on any larger quantity than a few grains of the 
car])onate, a wide delivery-tube should be employed ; or if a 
narrow one is employed, the end of it must occasionally be 
cleared from any bicarbonate that may have been deposited 
in it. A more economical arrangement of the apparatus 
employed in this process will be described under the corre- 
sponding sodium salt (p. 88). 

Deposition of the bicarbonate e.rp/amec?.— Potassium bicarbonate 
is to a certain extent soluble in water; but as it is less so than 



POTASSIUM. 11 

the potassium carbonate, and as a saturated solution of the latter 
is employed, the precipitation of a part of the bicarbonate inevi- 
tably occurs. In other words, the quantity of water present is 
sufficient to dissolve the carbonate, but insufficient to retain in 
.solution the whole of the bicarbonate formed during the action. 

Properties. — Prepared on the large scale, potassium bicarbonate 
occurs in colorless, non-deliquescent rhombic prisms ; it has a 
saline, feebly alkaline, non-corrosive taste. Heated to redness, 
it loses about 31 percent, of its weight, and is converted into 
potassium carbonate, water, and carbonic anhydride. 

2KHCO3 = K2CO3 4- HP + CO2 

198.82 137.27 17.88 43.67 

The foregoing equation and accompanying weights (see page 61) 
show how potassium bicarbonate loses 31 percent. (17.88 -f- 43.67 
in 198.82) when completely decomposed by heat. 

Notes on Nomenclature. — The prefix bi-m the name ''potassium 
bicarbonate, ' ' serves to recall the fact that for the same quantity 
of potassium this salt contains twice as much carbonic acid 
radical as is present in the carbonate. The salt is really a I 

''potassium and hydrogen carbonate," KHCO3, and is inter- \' 

mediate between potassium carbonate, K2CO3, and hydrogen car- 
bonate, or true carbonic acid [H2CO3]. It is "potassium acid 
carbonate" or "potassium hydrogen carbonate," and is an acid 
salt, inasmuch as it contains hydrogen which is displaceable 
by metal to form a normal salt, although it is not acid to the 
taste. 

Salts whose specific names end in the syllable ' ^ate* ' (carbonate, 
sulpha?^e, etc.) are in general conventionally so termed when they 
contain the radical (or characteristic group of elements) of an 
acid whose name ends in "ic," and from which acids they have 
been or may be formed. Thus the syllable ' 'ate, ' ' in the words 
sulpha^'e, nxirate, acetai^e, carbona^'e, etc., indicates that the re- 
spective salts contain the radical of an acid whose name ends in 
ic, the previous syllables sulph-, acet-, carbon-, indicating what 
that acid is — sulphuric, nitric, acetic, or carbonic. Occasionally 
a letter or syllable is dropped from or added to a word to render 
the name more euphonious ; thus the sulphuric radical forms 
sulphates, not sulphurates, and the tartaric radical yields tartrates 
not tartarates. 

Potassium Citrate. 

Experiment 5. — Dissolve a few grains or more of potassium 

carbonate in water, and add citric acid, H.,C,,H.^O., until it no 

longer causes effervescence. The resultino- liquid is a solution 

of potassium citrate, KgCgHsO^. Evaporate to dryness, in 



i 



78 THE METALLIC RADICALS. 

an open dish, cautiously so as to avoid charring; a pulverulent or 
granular residue is obtained, which is the official potassium 
citrate {Potassii CitrasU. S. P.)? a white deliquescent powder. 

SK.CO^ + 2K,CJi fi^ = 2K.fi fifl^ + 3H,0 + SCO, ♦ 

Potassium Citric acid Potassium Water Carbonic 

carbonate citrate anhydride 

A granulated mixture prepared from potassium citrate, sodium 
bicarbonate, and tartaric and citric acid is official {Potassii Citras 
Effervescens). 

Citrates. — The citric radical, CgH.O/^^, which with three 
atoms of hydrogen forms citric acid, and with three of potassium 
forms potassium citrate, is a trivaleut group. An extended form- 
ula for citric acid is C3H4.0H.(COOH)3,H20, that for potassium 
citrate being C3H^.OH.(COOK)3,H20. The chemistry of citric 
acid and other citrates will be described subsequently. 

Potassium nitrate, KNO, {Potassii Nitron U. S. P.), and Potas- 
sium sulphate, K2SO4 {Potassii Sulphas, U. S. P. ). These salts 
could also be made by neutralizing nitric acid, HNO3, and sul- 
phuric acid, HjSO^, respectively, with potassium carbonate. Or- 
dinarily they are not made in this way — the nitrate occurring, as 
already stated, in nature, and the sulphate being obtained as a 
by-product in many operations. Both salts will be alluded to 
later in connection with nitric acid. 

Potassium Tartrate. 

Experiment 6. — Place a few grains of potassium carbonate 
in a test-tube with a little water, heat to the boiling-point, 
and then add acid potassium tartrate, KHC_^H^Og, till there 
is no more effervescence; a solution of normal potassium 
tartrate, ICC^H^Oe, results. Prismatic crystals may be 
obtained on concentrating the solution by evaporation and 
setting the hot liquid aside. Larger quantities are made in 
the same way, 20 parts of potassium hydrogen tartrate and 9 
of potassium carbonate (with 50 of water) being about the 
proportions necessary for neutrality. 

2KHC,Hp, + K,C03 = 2K,C,Hp, + H,0 + CO., 

Potassium Potassium Potassium Water Carbonic 

hydro<^en tartrate carbonate tartrate anhydride 

Potassium tartrate is slightly deliquescent, and is soluble in about 
four parts of boiling water. 

Tartrates. — The bivalent radical CJip/^ is characteristic' of all 
tartrates ; hence the formula of hydrogen tartrate, or tartaric acid, 
is HX\H,0,; that of potassium" tartrate is (K.,C,H,0g),,H20; of 
the intermediate salt, acid i)otassium tartrate (cream of tartar), 
KHC^HPg. If the acid tartrate of one alkali-metal and the car- 



POTASSIUM. 79 

bonate of another interact, a neutral tartrate results, which con- 
tains both metals, as seen in Rochelle salt, KNaC4H40g,4H20 
{Potassii et Sodii Tartras, U. S. P.) More extended formulse of 
these salts, indicating constitution, are : — 

(CHOH),(COOH), [(CHOH),(COOK)J„ H,0 

Hydrogen tartrate Potassium tartrate 

(CHOH),COOH.COOK (CHOHI^COONa.COOK, 4R,0 

Hydrogen potassium tartrate Potassium and sodium tartrate 

Acid Salts {e.g. KHC^H^Og), that is, salts intermediate in com- 
position between a normal salt {e.g. KjC^H^Og) and an acid {e.g. 
H.^C^H^Og), are frequently met with. All acid radicals, except 
those which are univalent, may be concerned in the formation of 
such acid salts. See p. QQ. 

Potassium Iodide. 

Experiment 7. — Into a solution of potassium hydroxide 
heated in a test-tube, flask, or evaporating-basin, according to 
quantity, stir a little solid iodine. The deep color of the iodine 
disappears entirely« This is due to the formation of the colorless 
salts, potassium iodide, KI, and potassium iodate, KIO^, which 
remain dissolved in the liquid. Continue the addition of iodine 
so long as its color, after a few minutes' warming and stirring, 
disappears. When the whole of the potassium hydroxide in 
the solution has been converted into the salts mentioned, the 
slight excess of iodine remaining in the liquid will color it, 
and thus show that this stage of the operation is completed. 



6K0H + 31^ 


- 5KI + KIO, + 


3H,0 


Potassium Iodine 


Potassium Potassium 


Water 


hydroxide 


iodide iodate 





Separation of the iodide from the iodate. — Evaporate the 
solution to dryness. If both salts w^ere required, the result- 
ing mixture might be digested in alcohol, which dissolves the 
iodide but not the iodate. But the iodide only is needed. 
Intimately mix the residue, therefore (reserving a grain or 
two for a subsequent experiment), with excess (about a third 
of its weight) of charcoal, and gently heat in a test-tube or 
crucible until slight deflagration ensues.^ The crucible may 

^ If, in the operation of heatinsi; potassium iodate with charcoal, excess 
of the latter be employed, slight incandescence rather than deflagration 
occurs ; if the charcoal be largely in excess, the reduction of the imtassinni 
iodate to iodide is affected without visible deflagration or even incandes- 
ence. Deflagration means violent burning, from fidgratiis, burnt (flaijro, 1 
burn), and de, a prefix augmenting the sense of tlie word to which it may 
be attached. Paper thrown into a fire simply burns, nitre causes defla- 
gration of the fuel. Detonation {detono) is a similarly constructed word, 
meaning explosion with violent noise. 



80 THE METALLIC RADICALS. 

be supported in the flame of a spirit-lamp or Bimsen burner, 
or placed in a fire or furnace. The iodide remains unaffected ; 
but the iodate loses all its oxygen and is reduced to the state 
of iodide. 



KIO, 


-h 


3C 


= KI + 


SCO 


atassium 




Carbon 


Potassium 


Carbonic 


iodate 






iodide 


oxide 



Treat the mass with a little water, and filter to separate 
excess of charcoal; a solution of pure potassium iodide results. 
The latter may be used as a reagent, or it may be evap- 
orated to a small bulk and set aside to crystallize. 

Properties. — Potassium iodide {Fofassii lodidum,' U. S. P.), 
crystallizes in small cubical crystals, very soluble in water, less so 
in alcohol. Exposed to air and sunlight, pure potassium iodide 
becomes slightly brown, owing, probably, to the combined action 
of the oxygen, water vapor, and carbonic anhydride of the atmos- 
phere. 

The addition of charcoal in the above process is simply to 
facilitate the removal of the oxygen from the potassium iodate. 
Potassium iodate, KIO3, is analogous in composition to potassium 
chlorate, KCIO3, which has already been stated to be more gener- 
ally used than any other salt for the actual preparation of oxygen 
gas itself, and the removal of its oxygen may be accomplished 
by heating the residue without charcoal. In this case the liber- 
ated oxygen can be detected by inserting a glowing strip of wood 
into the mouth of the test-tube in which the mixture of iodide 
and iodate is being heated. The charcoal, however, removes the 
oxygen more quickly and at a lower temperature, and thus econ- 
omizes both time and heat. 

Detection of iodate in iodide. — Potassium iodate remaining as an 
impurity in potassium iodide, may be detected by adding to a 
solution of the latter salt some weak acid (say, tartaric), shaking, 
and then adding starch mucilage; blue "iodide of starch" {see 
Starch) is formed if a trace of iodate be present, but not other- 
wise. By the interaction of the added acid and the potassium 
iodate, iodic acid, HIO3, is produced; and by interaction of the 
added acid and the potassium iodide, hydriodic acid, HI, is pro- 
duced; neither of these alone attacks starch, but by their mutual 
interaction they yield free iocKne, which then forms the blue color 
by its action on the starch. This experiment should be tried on 
a grain or two of pure iodide and on the impure iodide reserved 
from the previous experiment. 

Potassium iodide containing iodate would obviously yield free 
iodine, which is excessively corrosive, on the salts coming into 
contact with the acids of the stomach. 

HIO3 -1- 5HI = 3H2O + 3I2. 



POTASSIUM. 81 

Note on Nomenclature. — The final syllable ide in the name 
potassium iodide, indicates that the element iodine is combined 
with potassium. An \od.ate, as already explained, is a salt con- 
taining the characteristic radical of iodic acid and of all other 
iodates. Inorganic salts whose names end in ide, are derived from 
acids which do not contain oxygen. Acids with complex radi- 
cals, the latter usually containing oxygen, give rise to salts with 
names ending in ate (see p. 77) or ite. An inorganic salt whose 
name ends in ate contains the radicals of an acid whose name 
ends in ic ; a salt whose name ends in ite contains the radical of 
an acid whose name ends in ous ; an inorganic salt whose name 
ends in ide contains an element for its acid radical. Thus, an inor- 
ganic sulphf (ie consists of a metallic radical combined with sulj^hur 
only, while a sulph//'e and a sulpha^'e are compounds of metallic 
radicals with the sulphuroz^s and the sulphuric acid radicals respec- 
tively, and so on with other inorganic '■ ^ ides, " ' ' ites, " or ' ' ates. ' ' 

Potassium Bromide [Potassii Bromidum, U. S. P.). — This salt is 
analogous in composition with potassium iodide, and is made in 
the same way, bromine being substituted for iodine. The for- 
mula of bromic acid is HBrOg. It will be noticed that the follow- 
ing equations are similar in character to those showing the prep- 
aration of potassium iodide : — 

6K0H + 3Br, = 5KBr + KBrOg + 3H,0 

Potassium Bromide Potassium Potassium Water 

hydroxide bromide bromate 

KBrOg + 3C = KBr + SCO 

Potassium Carbon Potassium Carbonic 

bromate bromide oxide 

Potassium Manganate and Permanganate. 

Experiment 8. — Place a fragment of solid potassium hy- 
droxide, KOH, with about the same quantity of potassium 
chlorate, KCIO^, and of black manganese oxide, MuO.„ on 
a piece of platinum foil.^ Hold the foil, by means of a 
small pair of forceps or tongs, in the flame of a blowpipe for 
a few minutes until the fused mixture has become dark 
green — apparently black. This color is that of jjotassium 
manganate, K^MnO^. 

6K0H + KCIO, + 3MnO, - 3K,MnO, + KCl + 3H,0 

Potassium Potassium Black man- Potassium Potassium Water 
hydroxide chlorate ganese oxide manganate chloride 

' The foil may be 1 in. broad by 2 in. long. No ordinary flame Avill 
melt the platinum, fused caustic alkalies only slowly corrode it, and 
very few other cliemical substances alfect it at all: hence the same ])iece 
may be used in experiments oA'er and over again. INiany metals I'orui a 
fusible alloy with platinum, and phosphorus and arsenous suli)hidc 
rapidly attack it; hence such substances, as well as mixtures likely to 
yield them, should be heated in porcelain vessels. 

6 



82 THE METALLIC RADICALS. 

Experiment 9. — Potassium PermaDganate (Potassii Per- 
mangauas, U. S. P.), KMnO^. Boil the potassium mauga- 
uate from Experiment 8 in water for a short time. Potassium 
permanganate is formed, and yields a purple solution. 

3K2Mn04 -f 2H2O = 2KMn04 + 4K0H + MnO^ 
Potassium Water Potassium Potassium Black man- 

manganate permanganate hydroxide ganese oxide 

On the large scale, the potassium hydroxide set free in the 
reaction is neutralized by sulphuric or, better, by carbonic acid, 
and the solution is evaporated to the crystallizing point. Manga- 
nate may also be changed into permanganate by treatment with 
chlorine. 

2K2Mn04 + CI2 = 2KC1 -f 2KMn04 

Solutions of potassium manganate (green) or permanganate 
(purple) and the analogous sodium compounds so readily yield 
their oxygen to organic matter that they are used on the large 
scale as disinfectants. 

Experiments dealing with the remaining official potassium 
compounds (namely, potassium bichromate, arsenite, chlorate, 
cyanide, ferrocyanide and ferricyanide), are deferred at present. 

Crystallization. — This operation will have been performed sev- 
eral times in the course of the foregoing experiments. Obviously 
it offers a mode of separating soluble crystallizable substances 
from soluble amorphous (a, a, without; iJiop&y, morphe, shape), 
substances; also of separating from each other, by frax^tional 
crystallization, substances of varying degrees of solubility. 

Analytical Reactions of Potassium Salts. 

Note. — Each reaction should be expressed in the form of an 
equation or diagram by the student in his note book. 

1. To a solution of any salt of potassium (chloride,^ for 
example) add a few drops of hydrochloric acid and of a 
solution of platinic chloride in hydrochloric acid (really 
chloroplatinic acid, H^PtClg)^ and stir the mixture with a 
glass rod; a yellow granular or slightly crystalline precipi- 
tate '"^ slowly forms. This precipitate consists of potassium 

^ A few fragments of potassium carbonate, two or three drops of 
hydrochloric-acid, and a small quantity of water, ^ive a solution of 
potassium chloride at once, K^COs + 2HCI=2KC1 + H2O + CO2. 

■^ Experiments with reagents containing platinum or other expensive 
metals are economically performed iu watch-glasses, drops of the liquids 
being operated on. 

•■' By precipitation (from pnecijntare, to throw down, suddenly) is 
simply meant the formation of particles of solid in a liquid, no matter 
whether the solid, the precipitate, subside or floats, and no matter 
wliether the operation be partial or complete. 



POTASSIUM. 83 

chloroplatinate, K^PtCl,; it is very spariogiy soluble in water, 
and practically insoluble in alcohol. 

Memoranda.— When the precipitate forms very slowly, it is 
sometimes of an orange-yellow tint. If potassium iodide happen 
to be the potassium salt under examination, compounds of iodine 
and platinum will be formed, giving a red color to the solution, 
and a larger quantity of the precipitant (that is the precipitating 
agent) will be required. 

Educational Note. —The thoughtful student will not confuse the 
test with the chemistry of the test. The test itself appeals to the 
senses; commonly to the eye, sometimes to the nose, occasionally 
to the ear. A person may be able to apply a test, and yet never 
know anything of the chemistry of the test. 

2. Carnot' s test for potassium. — Mix one drop of a solu- 
tion of bismuth nitrate with one drop of a solution of sodium 
thiosulphate, and add to the mixture 10 c.c. or so of absolute 
alcohol. To the reagent so prepared, add one or two drops 
of a solution of a potassium salt. A yellow precipitate of 
potassium bismuth thiosulphate, K3Bi( 8203)3, is produced 
either immediately or very nearly so (depending upon the 
concentration of the solution of the potassium salt added). 
If produced in large quantity, the preciptate settles down in 
a bulky flocculent form. Although insoluble in nearly 
absolute alcohol, the precipitate is readily soluble in water 
and in dilute alcohol, hence it is essential that no consider- 
able quantity of water should be present. Very dilute solu- 
tions of potassium salts should be concentrated by evaporation 
before employing them for this reaction. 

Potassium Bitartrate. Potassium Hydrogen Tartrate. Acid 
Potassium Tartrate. 

3. To a solution of any salt of potassium add excess of a 
saturated solution of sodium bitartrate (sodium hydrogen 
tartrate), NaHC^H^O^, and shake or well stir the mixture; a 
white granular precipitate of potassium bitartrate (potassium 
hydrogen tartrate), KHC^H_^Og, will be formed. If the 
solution of potassium salt employed is alkaline (solution of 
potassium carbonate, for example), care must l)e taken to 
add the sodium hydrogen tartrate solution until the liquid, 
after thorough mixing, is acid to test paper, otherwise the 
precipitate will not be formed. (Solution of sodium hydrogn 
tartrate possesses a strongly acid reaction.) Test paper, .stc 
p. 99. 



84 THE METALLIC RADICALS, 

JS^ofe.—Bj "excess" of any test-liquid (such as the ''solution 
of sodium bitartrate" just mentioned) an excessively large 
quantity is not to be understood, but merely such a quantity of 
the reagent as is more than sufficient (however little more) to 
convert the whole weight of the compound attacked into the 
compound to be produced. Thus, in the present case, enough 
sodium hydrogen tartrate must be added to convert the whole of 
the potassium salt operated on into acid potassium tartrate. 
What the weight of salt operated on was, must be roughly esti- 
mated mentally by the operator. It is not necessary in analytical 
operations to know the exact weights of salts employed. The 
analyst must use his judgment, founded on his knowledge of the 
reaction (as shown by an equation), and of the molecular weights 
of the substances employed in the reaction, as well as by the 
rough estimate of the amount of material on which he is experi- 
menting. 

Limits of the test. — Acid potassium tartrate is soluble in 200 
parts of cold and in 16.7 parts of boiling water. Hence, in 
applying the acid sodium tartrate test for potassium, the solu- 
tions must not be hot. Even if cold, no precipitate will be 
obtained if the solutions are very dilute. This test, therefore, is 
of far less value than either of the two already mentioned. Acid 
potassium tartrate is less soluble in dilute alcohol than in water, 
so that the addition of alcohol renders the reaction somewhat 
more delicate. 

Cream of Tartar. — The precipitate is Pofassii Bitartras, U.S. P., 
long known as Cream of Tartar (although the official 23rej)aration 
is not formed in the above manner). 

Potassium and Sodium Tartrate. 

4. To some hot concentrated solution of sodium carbonate 
(about three parts), in a test-tube or larger vessel, add potas- 
sium bitartrate (about four parts) till no more effervescence 
occurs; when the solution is cold, crystals of potassium and 
sodium tartrate, KNaC^Hp^ 4H.,0,(Po/a.s.s/i d Sodii Tartra.% 
U.8.P. j, long known as Rochelle Salt, will be deposited. The 
crystals are large rhombic prisms. 

Na,C03 + 2KHC,HP3 = 2KNaC,Hp, -f Kfi -f- CO, 

Sodium Potassium Potassium and sodium Water Carbon'ic 

carbonate bitartrate tartrate anhydride 

5. The fJ am e-test. — Dip the looped end of a platinum wire 
into a solution of a potassium salt, and introduce the loop 
into the lower part of the flame of a spirit-lamp or Bunsen 
burner. A light violet or lavender tint will be communi- 
cated to the flame, an eflfect highly characteristic of salts of 
potassium. 



POTASSIUM. 85 

Potassium salts are not readily volatile. Place a frag- 
ment of carbonate, nitrate, or other potassium salt, on a piece 
of platinum foil, and heat the latter in the flame of a lamp; 
the salt may fuse to a transparent liquid and. flow over the 
foil ; water also, if present, will escape as steam, and black 
carbon be set free, if the salt happen to be a tartrate, citrate, 
etc.; but the potassium compound itself will not be vaporized 
to any appreciable extent unless exposed to an exceedingly 
high temperature. This is a valuable negative property, as 
will be evident when the analytical reactions of ammonium 
come under notice. 

6. A solution of sodium cobaltic nitrite ^ is a very delicate 
test for potassium, in the absence of ammonium, potassium 
salts forming with it a yellow precipitate of potassium cobaltic 
nitrite (Fischer's salt), K3Co(N02)g, even in extremely dilute 
solutions. 



QUESTIONS AND EXEECISES. 

Name the source of potassium. — Give the source, formula, and charac- 
ters of Potassium Carbonate. — What is the systematic name of Caustic 
Potash. State the chemical formula of Caustic Potash, — Construct an 
equation representing the reaction betweeu potassium carbonate and 
slaked lime. — Define a hydroxide. — What group of atoms is characteristic 
of all carbonates? — How is "Sulphurated Potash" made, and of what 
salts is it a mixture ?— What is the formula for the acid radical of all 
acetates? — Draw a diagram showing the formation of Potassium Acetate. 
— Give a process for the conversion of carbonates into other salts. — What 
is the difference between Potassium Carbonate and and Bicarbonate? 
How is the latter prepared ? — What is the relation between salts 
whose specific names end in the syllable " ate,'' and acids ending in" /c," ? 
— Construct diagrams or equations representing the formation of Po- 
tassium Tartrate from Acid Tartrate, and Potassium Citrate from Car- 
bonate. — Distinguish between a normal and an acid salt. — How is Potas- 
sium Iodide made? — Illustrate the process either by diagrams or equa- 
tions. — Calculate how much potassium iodide is producible from 1000 
grains of iodine. Ans., 1308.5 grains. — Give a method for the detection 
of iodate in potassium iodide. Explain the reaction.- -What is the signifi- 
cation of the termination ^'ide" h\ chemical nomenclature? — State the 
relations between sulphides, sulphites, and sulphates.— Mention the 
chemical relation of Potassium Bromide to Potassium Iodide. — Describe 
the formation of Potassium Permanganate, giving equations or diagrams. 
— How do manganates and permanganates act as disinfectants? — Enu- 
merate the tests for potassium, explainiug by diagrams or equations the 
various reactions which occur. 



^ Sodium Cobaltic Nitrite Test Solution, V. S. P., is made by dissolving 
4 Gm. of cobaltons nitrate and 10 ({m. of sodium nitrite in r>0 i\c. of 
water, adding 2 C.c. of acetic acid and diluting with water to 100 C\c. 



86 . THE METALLIC RADICALS. 

SODIUM: Na. Atomic weight, 22.88. 

Occurrence, etc. — Most of the sodium salts met with in phar- 
macy are obtained directly from sodium carbonate, which is now 
manufactured on an enormous scale from sodium chloride (com- 
mon salt, sea-salt, bay-salt, or rock-salt), the most abundant of 
the sodium salts. When pure common salt {S'oclii Chloridum, 
U. S. P.), occurs as a white crystalline powder or transparent cubic 
crystals, free from moisture; the best varieties commonly contain 
a little magnesium chloride, and sometimes other impurities. 
Besides the direct and indirect use in medicine of sodium carbon- 
ate, or '* carbonate of soda " as it is commonly called, this sub- 
stance is largely used for household cleansing purposes, under the 
name of "washing soda," and in the manufacture of soaj). 
Sodium nitrate also occurs in nature, but is valuable as a nitrate 
rather than as a sodium salt. Sodium in the form of one or other 
of its comj^ounds, is a constituent of about forty chemical or 
galenical preparations of the Pharmacopoeia. 

Sodium is prepared by a process similar to that for potassium, 
but at a somewhat lower temperature. Castner obtained it com- 
paratively cheaply by distillation from a mixture of sodium 
hydroxide, carbon and iron, contained in steel vessels. The 
modern Castner process for preparing sodium, by which large 
quantities are now obtained, consists in electrolyzing fused sodium 
hydroxide. The metal has a bright metallic lustre when freshly 
cut, but is rapidly attacked by atmospheric oxygen, moisture and 
carbonic anhydride, and eventually becomes coated with sodium 
carbonate. Thrown upon the surface of water, sodium displaces 
hydrogen from the water, yielding solution of sodium hydroxide; 
but unless the sodium is confined to one spot, by placing it on a 
small floating piece of filter-paper, the action is not sufficiently 
intense to cause ignition of the escaping hydrogen. When the 
latter does ignite, it burns with a yellow flame, due to the pres- 
ence of a small quantity of sodium vapor. 

2Xa + 2H2O = H2 + 2XaOH 

Sodium Water Hydrogen Sodium hydroxide 

Sodium similarly attacks alcohol, yielding sodium ethylate {see 
Index). It maybe kept beneath the surface of mineral naphtha, 
or in sealed tins out of contact with air. It crystallizes in octa- 
hedra. 

Sodium Hydroxide. Caustic Soda. 

The formation of solution of sodium hydroxide, or caustic soda, 
NaOH, is effected by a process resembling that employed for 
making solution of potassium hydroxide, already described. 



Na,CO, 


j_ 


Ca(OH), 3: 


= 2NaOH 


+ 


CaCOa 


Sodium 




Calcium 


Sodium 




Calcium 


carbonate 




hydroxide 


hydroxide 




carbonate 



SODIUM. 87 

The remarks made concerning the general properties of solution 
of potassium hydroxide apply to this solution also. 

In the Castner process, which is in operation on the manufac- 
turing scale, sodium hydroxide {Sodil Ifi/droxidu7)i, U. S. P.), is 
obtained as a product of the electrolysis of a solution of sodium 
chloride. The chlorine simultaneously liberated at the anode as 
another product of this electrolysis, is used in the manufacture of 
bleaching powder {see p. 119). 

The interaction of sulphur and sodium carbonate at a high 
temperature resembles that of sulphur and potassium carbonate; 
but as the product is not used in medicine the experiment may be 
omitted. It is mentioned here to draw attention to the general 
resemblance of the potassium salts to those of sodium. 

Sodium Acetate- 
Experiment 1. — Add sodium carbonate (in powder or, bet- 
ter, in fragments) to some moderately concentrated acetic acid 
in an evaporating-basin as long as effervescence occurs, and 
then boil off some of the water. When the fluid is cold, 
crystals of sodium acetate, NaC^H^O^, SH^O (Sodii Acetas, 
U. S. P.), will be deposited. A ten percent, solution in 
distilled water forms " Sodium Acetate Test Solution," U. S. P. 



Na^CO, + 2HC,H,0, = 


= 2NaC,H,0, 


+ HP 4- CO, 


Sodium Acetic 


Sodium 


Water Carbonic 


carbonate acid 


acetate 


anhydride 



]} 

Sodium acetate effloresces (see p. 90) in dry air, and loses all jh 

its water of crystallization when gently heated. It withstands a j r 

temperature of 270° to 280° F. (about 132° to 138° C.) without f\ 

decomposition, but above 300° F. (about 149° C.) it rapidly 
chars. Its extended formula, is CHg. COONa, 311,0. 

Sodium Bicarbonate. Sodium Hydrogen Carbonate. 

The action of carbonic anhydride and water on sodium car- 
bonate, Na.^CO^, resembles that on potassium carbonate, but 
is carried out in a different manner. The result is sodium 
bicarbonate, NaHCOg {Sodii Bicarhonas, U. S. P.). 



Na,C03 


+ 


H,0 


+ CO, = 


2NaHC0, 


Sodium 




Water 


Carbonic 


Sodium 


carbonate 






anhydride 


bicarbonate 



Experiment 2. — Heat crystals of sodium carbonate, NaCOs, 
lOHgO (washing soda), in a porcelain crucible until no more 
steam escapes. Rub the product, in a mortar, with two-thirds 
of its weight of the same crystallized salt which has not been 
deprived of its water, and place the powder in a test-tube or 



88 



THE METALLIC RADICALS. 




small bottle into which carbooic anhydride may be conveyed 
by a tube passing through a cork and terminating at the 
bottom of the vessel. To generate the carbonic anhydride, fill 
a test-tube having a small hole in the bottom (or a piece of 
wide glass tubing, the lower end of which is plugged by a 
grooved cork), with fragments of marble, insert a cork and 
delivery-tube, and connect the latter, by means of a piece of 

India-rubber tubing, with the 
^^^* tube leading into the vessel 

containing the sodium carbon- 
ate. Now plunge the tube 
which contains the marble 
into a test-glass, or other vessel, 
containing a mixture of one 
part of hydrochloric acid and 
two parts of water, and loosen 
the cork of the sodium carbon- 

T3 .. ^ T K- T. ^ ate tube until carbonic anhy- 

Preparation of sodium bicarbonate. J 

dride, generated from the mar- 
ble, may be considered to have displaced all the air of this 
tube ; then replace the cork tightly and set the apparatus aside. 
As the gas is absorbed by the sodium carbonate, hydrochloric 
acid rises into the tube containing the marble, and generates 
fresh gas, which, in its turn, drives back the acid liquid, and 
thus prevents the production of any more gas until further 
absorption has occurred. When the salt is wholly converted 
into bicarbonate, NaHC03, ^* ^^'^^^ ^^ found to have become 
damp through the liberation of some water from the crystal- 
lized carbonate, Na^COg, lOH^O. (It would be inconveniently 
moist, even semi-fluid, if a part of the carbonate had not pre- 
viously been rendered anhydrous.) On the large scale, the 
resulting bicarbonate may be freed from any carbonate or 
traces of other salts, by adding half its bulk of cold distilled 
water, setting aside for about half an hour, shaking occasion- 
ally, draining the undissolved portion, and drying it by ex- 
posure to the air on filter-paper. 

This arrangement of apparatus for the preparation of sodium 
bicarbonate may be adopted for potassium bicarbonate, one part 
of potassium carbonate dissolved in two and a half parts of water 
being subjected to the action of the gas, and not the solid carbon- 
ate, as in the case of the sodium salt. 

The sodium carbonate may be placed not in a test-tube or 
bottle, but in a vertical tube, the bottom of which is loosely closed 



SODIUM. 89 

by a grooved cork. Any water of crystallization that is set free 
then runs off into a vessel that is placed beneath, and takes with it 
impurities (chlorides, sulphates, etc.), that may have been present 
in the original salt. 

The Ammonia Process. 

Sodium bicarbonate is now prepared on the manufacturing scale 
by treating a concentrated solution of sodium chloride, which has 
been saturated with ammonia, with carbonic anhydride under a 
pressure somewhat greater than that of the atmosphere. Sodium 
bicarbonate, which is sparingly soluble, is slowly precipitated. 
The ammonia and the carbonic anhydride may be considered 
to behave in the reaction as ammonium bicarbonate. 



NH.HCOg 


+ 


NaCl = 


= NaHCOg 


+ NH.Cl 


Ammonium 




Sodium 


Sodium 


Ammonium 


bicarbonate 




chloride 


bicarbonate 


chloride 



Ammonia is recovered from the resulting ammonium chloride 
and is again used for saturating solution of sodium chloride which 
is to be employed in subsequent operations for preparing further 
quantities of sodium bicarbonate. Washing soda, Na2C03, lOH^O, 
is made by heating the bicarbonate thus obtained, and crystal- 
lizing from aqueous solution, the carbonic anhydride liberated 
during the heating process being also utilized in the preparation 
of further quantities of sodium bicarbonate. 

2NaHC03 = Na,C03 + H^ + CO, 

Sodium Sodium Water Carbonic 

bicarbonate carbonate anhydride 

Sodium bicarbonate may be medicinally administered in the 
form of lozenge {Trochicus Sodii Bicarbonaiis, U. S. P.). 

Sodium Carbonate. 

Sodium carbonate may be obtained by heating the sodium 
bicarbonate produced by the ammonia process described above, 
the resulting salt being anhydrous. 

Sodium carbonate is also prepared on the large scale by the 
Leblanc process. Sodium chloride is first converted into sul- 
phate (salt-cake) by heating it with sulphuric acid :— 

2NaCl + H^SO, = Na.SO, + 2HC1 

The sulphate is then roasted Avith the limestone and small coal, 
sodium carbonate and calcium sulphide being formed: — 

Na^SO, + 2C + CaC03 = CaS + '^^.fiO^ + 2C0, 
The resulting mass (black-ash) is lixiviated. {LLricia, from U.i\ 
lye — water impregnated with alkaline salts; hence livivUxtioiK the 
operation of washing a mixture with a view to dissolve out soluble 
constituents. If relatively small quantities of solvents bo em- 



90 THE METALLIC RADICALS. 

ployed, the solution by lixiviation will be more or less fractional, 
substances of varying solubility being thus more or less separated 
from each other.) The sodium carbonate dissolves, the calcium 
sulphide remaining insoluble. The solution is evaporated to dry- 
ness, and yields crude sodium carbonate. This is roasted with a 
small quantity of sawdust, to reconvert into carbonate any caustic 
soda produced by the action of lime on the sodium carbonate. 
The product is soda-ash. Dissolved in water and crystallized, it 
constitutes ordinary "washing-soda": recrystallized (and some- 
times ground) it forms purified sodium carbonate, NagCOg, IOH2O. 

In the Hargreaves-Bird electrolytic process for the manu- 
facture of sodium carbonate, the sodium hydroxide obtained by 
the electrolysis of a solution of sodium chloride is treated with a 
mixture of steam and furnace gases (the latter furnishing carbonic 
anhydride), whereby a solution is obtained which only requires 
evaporation to a small extent in order to yield crystals of sodium 
carbonate on cooling. 

A crystal of decahydrated sodium carbonate is sodium carbonate 
plus "water of crystallization "; on heating it, part or (at 100°C.), 
the whole of the water is evolved. The sodium carbonate of the 
Pharmacopoeia is the monohydrated salt, Na2C03, HgO (Sodil 
Carbonas Monohydratus, U. S. P.). The decahydrated salt loses 
nine-tenths of its water at about 35° C, leaving the monohydrated 
salt. The official salt is the latter in the form of a ciystalline 
granular powder, which is scarcely affected by exposure to air 
under ordinary conditions. 

Water of Crystallization . — Anhydrous and Hydrous Salts. Ef- 
florescence. Anhydrides. — A number of salts, when crystallizing 
from aqueous solution, take uj) w^ater to a greater or less extent 
from the solution. Sometimes the same salt is capable of com- 
bining with water in two or more different proportions. Salts 
which do not combine with water in this way are often called 
anhydrous (from «,, a, without, and v6up, hudor, water) as dis- 
tinguished from those w^hich do, and are, in consequence, called 
hydrous salts. The water so taken up by certain salts in crystal- 
lizing is generally called water of crystallization. Many hydrous 
salts, when simply exposed to moderately dry air at ordinary tem- 
peratures, lose water and crumble to a fine powder. This pro- 
cess is known as efflorescence (efflorescens, blossoming forth, in al- 
lusion to the appearance of the product). The water of crystal- 
lization is usually (although not in all cases completely) expelled 
from a hydrous salt by heating it to a temperature of 100° to 
150° C. In the chemical formulfe of salts with water of crystal- 
lization, the symbols representing water are usually separated 
by a comma, or, as in the U. S. P., by the + sign, from those 
representing the salts. The crystals of sodium acetate (Experi- 
ment 1, p. 87) are represehted by the formula NaC2H302, SUfi, 
and those of decahydrated sodium carbonate by the formula 



SODIUM. 91 

NagCOg, IOH2O. It is possible, however, that this so-called water 
of crystallization is in a more intimate state of combination than is 
indicated by such formulae as those just given. Anhydrides form 
a distinct class of chemical substances derived from or related to 
acids : in short, they may be regarded as acids from which the 
elements of water have been removed, the essential chemical proper- 
ties of the acids being thereby greatly altered. 

Deliquescence. — Sodium carbonate and potassium carbonate, 
chemically closely allied, differ physically. Potassium carbonate 
quickly absorbs moisture from the air and becomes damp, wet, 
and finally a solution — it is deliquescent {deliquescens, melting 
away). Decahydrated sodium carbonate, on the other hand, is 
efflorescent, and yields water of crystallization to the air, the 
crystals becoming white, opaque, and pulverulent. 

Sodium Hypochlorite. 

Experiment 3. — Triturate in a motar 2 parts of chlorinated 
lime with a solution of 1.3 parts of monoliyd rated sodium car- 
bonate in 20 of water, and filter. 

[Ca(C10)2 + CaClJ + SNa^COg = 2[NaC10 + NaCl] + 2CaC03 

Chlorinated Sodium Chlorinated Calcium 

lime carbonate soda carbonate 

This solution is an old and very useful disinfectant, formerly 
known as Labarraque' s liquor and Eau de Javelle. It contains 
about 2| percent, of avaible chlorine. 

The official Liquor Sodoe Chlorinatce is prepared in a somewhat 
analogous manner, but with certain additional details. It should 
contain at least 2.4 percent, of available chlorine. 

Sodium Iodide and Sodium Bromide. 

These salts, Nal and N'aBr {Sodil lodidum, U. S. P., and Sodii 
Bromidum, U. S. P.), are analogous in composition with potassium 
iodide and bromide, and are prepared by a similar method, 
sodium hydroxide being used in place of potassium hydroxide. 
Sodium bromide, however, must be crystallized from warm solu- 
tions, otherwise, rhombic prisms containing water, NaBr,2H20, 
will be deposited. 

Other Sodium Compounds. 

Experiments dealing with the chemistry of the remaining im- 
portant sodium compounds (namely, nitrate, sulphate, thiosul- 
phate, borate, arsenate, valerianate, and ethylate) are deferred for 
the present. 

Sodium Phosp/iafe. — The prepar;ition and composition oi' this 
salt will be most usefully studied after bone-ash has boon 



92 THE METALLIC RADICALS. 

described. Bone-ash is impure calcium phosphate and is the 
starting jioint for the preparation of most other phosphates and 
for phosphorus itself 

Sodii Phosphas Effervescens, U. S. P., is made by mixing the 
anhydrous phosphate [Sodii Phosphas Exsiccatus U. S. P.), with 
sodium bicarbonate and tartaric and citric acids. 

Sodium peroxide, NagOg, a compound now manufactured on 
a large scale, is used as a bleaching agent, and in chemical 
analysis as an oxidizing agent. 

Analogies of Sodium and Potassium salts. — Other reactions 
similar to those given under potassium might be mentioned 
here, and the preparation of sodium citrate, {Sodii Cltras, U. S. P.), 
iodate, bromate, chlorate, {Sodii Chloras, U. S. P.), manganate, 
permanganate, and many other salts be described. But enough 
has been stated to show how sodium is chemically analogous to 
potassium. Such analogies will frequently present themselves. 

Substitution of Potassium and Sodium salts for each other. — 
Sodium salts being cheaper than potassium salts, the former may 
sometimes be economically substituted. That one is employed 
rather than the other, is often merely a result due to accident or 
fashion. But it must be borne in mind that in some cases a 
potassium salt crystallizes more readily than its sodium analogue, 
or that a sodium salt is unchanged by exposure to the air when 
the corresponding potassium salt has a tendency to absorb moist- 
ure; or one may be more soluble than the other, or the two may 
have different medicinal eflFects. For these or similar reasons, a 
potassium salt has come to be used in medicine or trade instead 
of the corresponding sodium salt, and vice versa. When a salt is 
employed as a source of a particular acid radical, the least expensive 
salt of that radical is nearly always selected. 

Analytical Reactions of Sodium Salts. 

1. The chief analytical reactions for sodium is the flame-test. 
When brought into contact with a Bunsen flame io the manner 
described under potassium (page 84), au intensely yellow color 
is communicated to the flame by any sodium salt. This is 
highly characteristic — indeed, almost too delicate a test; for if 
the end of the wire be touched by the fingers, enough sodium 
salt (which is contained in the moisture of the hand) adheres 
to the wire to communicate a very distinct sodium reaction to 
the flame. These statements should be experimentally veri- 
fied, sodium chloride, sulphate, or other salt being employed. 

2. Sodium salts, like those of potassium, are not volatile. 
Prove this fact by the means described where the effect of 
heat on potassium salt is referred to (p. 85). 



AMMONIUM, 93 

QUESTIONS AND EXEECISES. 

Explain the action of sodium ou water. What colors do sodium and 
potassium respectively communicate to flame ? — Sodium acetate : give 
formula and preparation, with equation. — Give a diagram showing the 
formation of Sodium Bicarbonate. — Why is a mixture of dried and un- 
dried sodium carbonate employed in the preparation of the bicarbonate? — 
State the difference between anhj'drous and crystallized sodium carbon- 
ate. — Define the terms anhydrous, hydrous, anhydride. — What do you under- 
stand by water of crystallization 1 — What is the systematic name of 
Rochelle Salt, and how is the salt prepared ? — What is the relation of 
Rochelle Salt to cream of tartar and tartaric acid? — Give the mode of 
preparaton of the official Solution of Chlorinated Soda, representing the 
process by a diagram. — Define deliquescoice, efflorescence, and lixiviatiou. — 
How are sodium salts distinguished from those of potassium ? 



li 



AMMONIUM. 

Radical of the araraonium compounds, NH^. 

The elements nitrogen and hydrogen, in the proportion of 
one atom of the former to four of tlie latter, (NH^), are present 
in all the ammonium compounds about to be studied, playing 
the part of metallic radical just as potassium (K) and sodium 
(Na) do in the potassium and sodium compounds. The group 
NH^ is univalent like potassium and sodium, and the am- 
monium compounds closely resemble those of potassium and 
sodium. Ammonium is said to have been isolated by Weyl, 
as an unstable dark-blue liquid possessing a metallic lustre. i;) 

[1 

Source. — The source of nearly all the ammonium salts met fj 

with in commerce is the ammonia gas, NH^, produced during 
the distillation of all kinds of coal in the manufacture of ordinary 
illuminating gas and of coke. This ammonia is no doubt derived 
from the nitrogen of the plants from which the coal has been 
produced. It is obtained as a by-product in the distillation of 
shale for the production of paraffin oil, and is also recovered from 
the furnace gases of iron-works. It is possible, however, to pro- 
duce ammonia from its elements. Thus when electric sparks are 
passed through a mixture of nitrogen and hydrogen, or when a 
similar mixture is passed over spongy ])latinum, some ammonia is 
produced. According to Eickman and Tlionn)son, coal-dust, air 
and vapor of water, all at a red heat, yiekl ammonia. Salt added 
to the mixture prevents the combustion of ammonia fornuMl, and 
ammonium chloride sublimes. 

Ammonium Chloride. — The ammonia liberated from the "ainuio- 
niacal liquor" of tlie gas-works by heat and by the concurrent 
action of slaked lime on the annnonium hydrosulphide, carbc^u- 
ate, and other salts present, when passed into hydrochloric acid, 



94 THE METALLIC RADICALS. 

yields crude ammonium chloride (salammoniac), NHg + CHI 
=NH^C1; and from this salt, purified, the others used in phar- 
macy are directly or indirectly made. Ammonium Chloride 
(Ammonii Chloridum, U. S. P.), occurs in colorless inodorous 
minute crystals, or in translucent fibrous masses, tough and diffi- 
cult to powder, soluble in water and in alcohol (90 percent.). 

Commercial ammonium chloride generally contains slight traces 
of iron oxychloride, tarry matter, and possibly compound am- 
monium chlorides {see ''Artificial Alkaloids" in Index). 

Ammonium Sulphate, (NH^)2S0^, is formed when the ammonia 
of the ammoniacal liquor is neutralized with sulphuric acid. It 
is largely used as a constituent of artificial manure; and when 
purified by recrystallization, is emj^loyed in pharmacy for pro- 
ducing the double ammonium and ferric sulphate (iron alum). 

Volcanic Ammonia. — A veiy pure form of ammonia is that met 
with in volcanic districts, and obtained as a by-product in the 
manufacture of borax. Crude boric acid as imported contains 5 
to 10 percent, of ammonium salts, either sulphate or that salt 
united with magnesium, sodium, or manganese sulphates, forming 
so-called double salts [Howard). 

Ammonium Amalgam. 

Experiment 1. — To forty or fifty grains of mercury in a 
dry test-tube, add one or two small pieces of sodium (freed 
from adhering naphtha by gentle pressure with a piece of filter- 
paper), and gently warm the tube, when the metals will unite 
with evolution of heat to form sodium amalgam. To this 
amalgam, when cold, add some fragmeuts of ammonium chlo- 
ride and a concentrated solution of the same salt. The 
sodium amalgam rapidly swells up and may even overflow 
the tube. The light spongy mass produced is the so-called 
ammonium amalgam, and the reaction is usually adduced as 
evidence of the existence of ammonium. The sodium of the 
amalgam unites with the chlorine of the ammonium chloride, 
while the ammonium is supposed to form an amalgam with 
the mercury. At ordinary temperatures the amalgam rapidly 
gives off' hydrogen and ammonia gases; this decomposition is 
nearly complete after some minutes, and mercury remains, 
together with the solution of sodium chloride. 

Ammonia Water. Ammonium Hydroxide. 

Experiment 2. — Heat a few grains of ammonium chloride 
with about an equal weight of calcium hydroxide (slaked lime) 
moistened with a little water in a test-tube ; ammonia eras is 



AMMONIUM. 95 

given off, and may be recognized by its pungent odor. It is 
very soluble in water. By means of a cork and delivery- 
tube, fitted as described for the preparation of oxygen and of 
hydrogen, pass some of the ammonia into another test-tube 
containing a little water. The end of the delivery-tube should 
only just dip beneath the surface of the water (or possibly, all 
the w^ater might rush back into the generating tube, on ac- 
count of the water greedily absorbing the ammonia gas). A 
solution of ammonia will thus be formed. 



2NH,C1 + 


Ca(0H)2 = 


= CaCl^ + 


2B.,0 


+ 2NH3 


Ammonium 


Calcium 


Calcium 


Water 


Ammonia 


chloride 


hydroxide 


chloride 







A molecule of ammonia is composed of one atom of nitrogen 
with three atoms of hydrogen; its formula is NH3. Two volumes 
of the gas contain one volume of nitrogen combined with three 
volumes of hydrogen. Its constituents have, therefore, in com- 
bining suffered condensation to one-half of their original bulk. 

The solution obtained by dissolving ammonia in water is believed 
to contain ammonium hydroxide, NH^OH, the analogue of potas- 
sium hydroxide, KOH, or sodium hydroxide, NaOH. The chemical 
grounds for this belief are the observed analogies of the well-known 
ammonium salts with those of potassium and sodium, the similarity 
of action of solutions of caustic potash, caustic soda, and ammonia 
on salts of most metals, and the asserted existence of crystals of 
an analogous sulphur salt (NH^SH). The formation of ammonium 
hydroxide may be illustrated by the following equation: — 

NH3 + H^O = NHpH 

Ammonia Water Ammonium 

hydroxide 

/Solutions of Ammonia, prepared by the above process on a large 
scale and in suitable apparatus (bottles being so arranged in a series 
as to condense all the ammonia evolved during the operation), are 
used in pharmacy — the one (sp. gr. 0. 897) containing 28 percent., 
the other (sp. gr. 0.958) 10 percent, by weight of ammonia, NH3 
{Aqua Ammoniac Fortior and Aqua Ammonia', U. S. P. One part, 
by measure, of the former, and two of water ar^ mixed in order to 
obtain the latter). 

Spiritus Ammonice, U. S. P., is alcohol (92.3 percent.), contain- 
ing 10 percent, by weight of ammonia, NH3. 

Ammonium Acetate. 

Experiment 3. — To diluted acetic acid in a test-tube add 
commercial ammonium carbonate until effervescence ceases, 
and the liquid, after well stirring or shaking, or perha}>s 



96 THE METALLIC RADICALS. 

warming, to get rid of carbonic anhydride, is only faintly acid 
to litmus (see p. 99). This solution, when of prescribed 
strength, forms the official Solution of Ammonium Acetate, 
xsH^C^HgOg (Liquor Ammonii Acetatis, U. S. P.)- On 
evaporating and cooling, ammonium acetate may be obtained 
in crystals, but some of the salt will then haye undergone de- 
composition into ammonia and acetic acid. In the rare case 
of exact neutrality being required, to the liquid which has 
been made slightly alkaline with excess of ammonium carbon- 
ate add acetic acid, finally drop by drop, until a drop of the 
resulting solution no longer giyes a white precipitate with a 
drop of a clear solution of ordinary lead acetate (on a piece 
of glass backed by black paper or black cloth). 

NH,HC03,NH,NH2C02+ 3HC2H302=3NH,C2H302+H20+ 2C0, 

Ammonium acid carbonate Acetic Ammonium Water Carbonic 

and carbamate acid acetate anhydride 

Solution of ammonium acetate can, of course, also be made by 
the inieraction of acetic acid and ammonia water; but the liquid, 
owing to the absence of dissolved carbonic acid, is too vapid for 
medicinal use. 

Ammonium Carbonates. 

Commercial ammonium carbonate is made by heating a mixture 
of calcium carbonate and ammonium chloride; calcium chloride, 
CaClg, remains, while water, H^O, and some ammonia, NH,, 
escape, and the ammoniacal carbonate distils or, rather sublimes ^ 
in cakes [Ammonii Carbona.s, U. S. P.). The best form of apparatus 
to employ is a retort with a short wide neck and a cool receiver. 
On the large scale the retort is usually iron, and the receiver 
earthenware or glass; on the small scale glass vessels are employed. 
The salt is purified by resublimation at a low temperature — 
150° F. (65.5° C.) is said to be sufficient. 

The salt, the empirical formula of which is N^H^^C.^O^, is prob- 
ably a mixture of one molecule (sometimes two) of ammonium 
hydrogen carbonate (ammonium bicarbonate), XH^HCOg, and 
one of a salt termed ammonium carbamate, NH^XH2C02. The 
latter belongs to an important class of salts known as carbamates, 
but is the only one of direct interest to the pharmacist. Cold 
water extracts it from commercial ammonium carbonate, leaving 
the greater part of the bicarbonate undissolved if the amount of 

1 Sublimation (from subli7nis, high) is the term applied to the evaporiza- 
tiou of a solid substance by lieat. and its subsequent condensation on an 
ui)p('r and cooler i>art of the vessel or apparatus in which the operation 
is performed. The product of sublimation is called a snhlimnte. Dif- 
ferent substances sublime at different temperatures, hence a mixture of 
volatile solids may sometimes be separated or fractionated bv sublimation. 



AMMONIUM, 97 

water used be very small. Alcohol also attracts the carbamate, 
leaving the bicarbonate undissolved. In contact with water the 
carbamate soon changes into normal ammonium carbonate: — 
NH4NH2CO2 + H2O = (NH J2CO3 ; so that an aqueous solution 
of commercial ammonium carbonate contains both hydrogen, am- 
monium carbonate, and normal ammonium carbonate. If to such 
a solution,' some ammonia be added, a solution of 7iormal am- 
monium carbonate is obtained: this is the common reagent found 
on the shelves of the analytical laboratory. Thus, " Ammonium 
Carbonate Test Solution," U. S. P., is prepared by dissolving the 
commercial salt in water to which solution of ammonia has been 
added. 

NH.HCOgjNH.NH^CO, + NH.OH - 2(NHJ,C03 

Normal ammonium carbonate is the salt formed on adding con- 
centrated solution of ammonia to the commercial carbonate in 
preparing a pungent mixture for toilet smelling-bottles; but it is 
unstable, and on continued exposure to air is converted into a 
mass of crystals of bicarbonate. 

If ammonium carbonate contain more than traces of empyreu- 
matic matters (from the gas-liquor), an aqueous solution of it, 
with excess of sulphuric acid added, will at once decolorize a 
dilute solution of potassium permanganate. 

Sal Volatile (Spiritus Ammotiioe Aromaticus, U. S. P.), is a spirit- 
uous solution of about 1 percent, of ammonia, NH3, nearly 4 per- 
cent, of normal ammonium carbonate, (NHJ^COg, with oils of 
nutmeg, lemon, and lavender flowers. Commercial samples con- 
tain salts equivalent to from 1 to nearly 3 percent, of ammonia, 
the official spirit yielding a total of nearly 2-| percent, of the gas. 

Ammonium Nitrate. 

Experiment 4. — To some dilute nitric acid add "ammonium 
carbonate," until, after well stirring, a slightly ammoniacal 
odor remains. The solution contains ammonium nitrate. 

NH,HC03,NH,NH,C02+3HN03=3NH,N03-f H2O + 2CO2 

Ammonium hydrogen carbonate Nitric Ammonium Water Carbonic 
and carbamate acid nitrate anhydride 

From a concentrated hot solution of ammonium nitrate, crys- 
tals may be obtained containing much water (NH^NO.,, 1 21I.,6). 
On heating these in a dish to about 320° F. (160° C.j the water 
escapes. The fused anhydrous salt remaining (NPI^NO..) may bo 
poured out on an iron plate. On further heating the fused nitrate, 
at 350° to 450° F. (about 177° to 232° C), ft is resolved int(^ 
nitrous oxide or laughing-gas and water, NH^N03 = N.,0 4- 2HoO. 

Nitrous oxide is prepared in this way for use as an anaesthetic. 
7 



98 THE METALLIC RADICALS. 

When required for inhalation, it is washed from any trace of 
nitric acid or nitric oxide by being passed through solution of 
potassium hydroxide and solution of ferrous sulphate, the formei 
absorbing acid vapors, the latter nitric oxide. It is slightly soluble 
in warm water, more so in cold. It supports combustion almost as 
well as oxygen. By the application of sufficient pressure it may 
be reduced to a colorless liquid, and by simultaneous cooling it 
can be solidified. Inhalation of a mixture of nitrous oxide and 
air causes laughter or other excitement. 

Ammonium Citrate, Phosphate and Benzoate. 

Experiment 5. — To a solution of citric acid, HgCgH.O., add 
ammonia water until the well-stirred liquid smells faintly of 
ammonia. Ammonium phosphate, (XH^J^^-IPO^ and am- 
monium benzoate, NH,C-H^O, (Ammonii Benzoas, U. S. P.), 
are also made by adding ammonia water to phosphoric acid, 
H^PO,^, and benzoic acid, HC.H.O^, respectfully, evaporating 
(keeping the ammonia in slight excess by adding more of its 
solution), and setting aside to crysttiUize. 

H,C,H,0. + 3XH,0H = (XHJ.^CgH.O, + SH^O 

Citric acid Ammonium Ammonium citrate Water 

hydroxide 

H,PO, + 2XH,0H = (XHJ,HPO, + 2H,0 

Phosphoric acid Ammonium Ammonium phosphate Water 

hydroxide 

HXHA ^- XHpH = XH,C,Hp, + H,0 

Benzoic acid Ammonium Ammonium benzoate Water 

liydroxide 

Ammonium phosphate occurs in transparent colorless prisms, 
soluble in water, insoluble in alcohol; ammonium benzoate occurs 
in crystalline plates, soluble in water and in alcohol. An ex- 
tended formula for ammonium benzoate is CgH..COOXH,; for 
ammonium citrate, C,H,.0H.(C00XH,)3. 

Ammonium Bromide, XH^Br, {Ammonii Bromidum, U. S. P.), 
will be noticed in connection with Hydrobromic Acid and other 
Bromides. Ammonium Iodide, XHJ, is also official [Ammonii 
lodidum, U. S. P.). 

Ammonium Oxalate. 

Experiment 6. — To a nearly boiling solution of 1 part of 
oxalic acid in about 8 of water add" ammonium carbonate 
until the liquid is neutral to test-paper (see following para- 
graphs), filter while hot, and set aside to crvstallize^ The 
product is Ammonium Oxalate, U. S. P., (NHj2C,0,,H.,0,or 
fCOOX'^Hj,, H^O. A solution of it is used as a reagent in 



AMMONIUM. 99 

analysis ; 1 part of the pure salt in 25 of water forms 
Ammonium Oxalate Test Solution, U. S. P. 

Sn.Cfi, + 2N3H,,C,05 = 3(NH,),C,0, + 4C0„ + 2Hp 

Oxalic "Ammonium Ammonium Carbonic Water 

acid carbonate" oxalate anliydride 

Neutralization. — Thus far the methods by which the student has 
avoided excess of either acid matter on the one hand, or alkaline 
on the other, have been the rough aid of taste, cessation of effer- 
vescence, presence or absence of odor, etc. More delicate aid is 
afforded by test-papers. 

Test-papers. — Litmus is a blue vegetable pigment, prepared from 
various species of Roccella lichen, exceedingly sensitive to the 
action of acids, which turn it red. When the reddened, alkalies 
(caustic potash or soda, and ammonia), and other soluble hydrox- 
ides, also alkali-metal carbonates, etc. , readily turn it blue. The 
student should here test for himself the delicacy of this action by 
experiments with paper soaked in solution of litmus and dipped 
into very dilute solutions of acids, acid salts {e.g., KHC^H^Og), 
alkalies, and such neutral salts as potassium nitrate, sodium sul- 
phate, or ammonium chloride. 

Litmus Test Solution (U. S. P.). — This is prepared from purified 
litmus. Gently boil litmus with four times its bulk of alcohol 
for an hour. Pour away the fluid and repeat the operation twice. 
Digest the residual litmus in cold distilled water and filter; then 
extract the residue with five times its weight of boiling water, and, 
after thoroughly cooling, filter. 

Blue litmus-paper (U.S. P.), is made by impregnating unglazed 
white paper with a solution of litmus. Red litmus-paper (U.S. P.), 
is made by impregnating unglazed white paper with solution of 
litmus, reddened by the previous addition of a very minute quan- 
tity of hydrochloric acid. 

Turmeric paper (U. S. P.), similarly prepared from Turmeric 
Tincture (U. S. P.), is occasionally useful as a test for alkalies, 
which turn its yellow to brown; acids do not affect it. Several 
other ''indicators" of alkalinity or acidity are used, such as 
Methyl Orange, Phenol-phthalein, and Cochineal Test Solutions, 

Ammonium Hydrosulphide and Sulphide. 

Experiment 7. — Pass hydrogen sulphide, H.,S, through a 
small quantity of ammonia water in a test-tube, until a por- 
tion of the liquid no longer causes a white precipitate in solu- 
tion of magnesium sulphate; the product is a solution of ammo- 
nium hydrosulphide, NH^SH. 

NHpH 1 H,S =. NH^SH -f- H.p 

''Ammonium Sulphide Test Solution," U. S. P., is made by 



100 



THE METALLIC RADICALS. 



saturating 3 parts by measure of ammouium water with washed 
hydrogeu sulphide, and then adding 2 parts by measure of 
ammonia water. The solution should be preserved in a well- 
stopped bottle. 

Hydrogen Sulphide or sulphuretted hydrogen is a poisonous 
gas possessing an unpleasant odor ; hence the above operation 
and many others, described farther on, in which this gas is 
indispensable, must be performed in the open air, or in a 
fuDie-ciqjboard — a chamber so contrived that noxious gases 
and vapors shall escape into a chimney in connection with the 
external air. In the above experiment, the small quantity 
of gas required can be made in a test-tube. Place some 
fragments of ferrous sulphide, FeS, in a test-tube, add water 
and then sulphuric acid; the gas is at once evolved, and may 
be conducted by a tube into the ammonia water. Ferrous 
sulphate remains in solution in the generating tube : — 

FeS -f H^SO, = H,S + FeSO, 

As heat is not necessary in the preparation of sulphuretted 
hydrogen, ''Hydrogen Sulphide," U. S. P., the test-tube of 
the foregoing operation may be advantageously replaced by a 
bottle, especially when larger quantities of the gas are re- 
quired. In analytical operations, the gas should be purified 
by passing it through water, contained in a second bottle. 

Fig. 20. 




Hydrogen sulphide apparatus. 

A convenient apparatus for experimental use is arranged 
as follows : — Two common wide-mouthed bottles are selected, 
the one having a capacity of about half a pint, the other a 
quarter pint; the former may be called the generating-bottle, 
the latter the ivash-bottle. Fit both bottles with good sound 



AMMONIUM. 101 

corks. Through each cork bore two holes of such a size that 
glass tubing of about the diameter of a quill pen shall fit 
them tightly. Through one of the holes in the cork of the 
generating-bottle pass a funnel-tube, so that its extremity may 
nearly reach the bottom of the bottle. To the other hole 
adapt a piece of tubing, 6 inches long, and bent in the middle 
to a right angle. A similar ''elbow-tube" is fitted to one of 
the holes in the cork of the wash-bottle, and another elbow- 
tube, one arm of which is long enough to reach near the 
bottom of the wash-bottle, is fitted to the other hole. Re- 
moving the corks, two or three ounces of water are now 
poured into each bottle, an ounce or two of ferrous sulphide 
put into the generating-bottle, and the corks replaced. The 
elbow-tube of the generating-bottle is now attached by a short 
piece of India-rubber tubing to the long-armed elbow-tube of 
the wash-bottle, so that gas coming from the generator may 
pass through the water in the wash-bottle. The delivery-tube 
of the wash-bottle is then lengthened by attaching to it, by 
means of India-rubber tubing, another piece of glass tubing 
several inches in length. The apparatus is now ready for use. 
Concentrated sulphuric acid is poured down the funnel-tube in 
small quantities at a time, until brisk effervescence is estab- 
lished, and more is added from time to time as the evolution 
of gas becomes slow. The gas passes through the tubes into 
the wash-bottle, where, as it bubbles up through the water, 
any trace of sulphuric acid, or other matter mechanically 
carried over, is arrested, and thence the gas flows out at the 
delivery-tube into any vessel or liquid that may be placed 
there to receive it. The generator must be detached occa- 
sionally, and the ferrous sulphate w^ashed out of it. Should 
difficulty be experienced in obtaining sufficiently sound corks 
to make gas-tight fittings for the apparatus, double-bored 
rubber stoppers, obtainable from any apparatus dealer, mav 
be employed. 

Hydrogen sulphide dissolves in water to a moderate extent, 
yielding a solution which smells strongly of the gas, and is 
frequently employed as a reagent. When the solution is 
exposed to air the hydrogen sulphide rapidly undergoes 
oxidation with deposition of white sulphur : — 

2H^S + O.^ ^- 2H.p + S., 



102 THE METALLIC RADICALS. 

Analytical Reactions of Ammonium Salts. 

1. To a solution of au aiiimouium salt (ammonium chloride, 
for example), iu a test-tube, add solution of sodium hydroxide 
(or potassium hydroxide, or slaked lime), and warm the 
mixture; a characteristic odor (ammonia, NH3) results : — 
NHp+NaOH=NH3+Hp + NaCl. 

The recognition of the odo7' of ammonia is one of the 
readiest means of detecting the presence of this substance; 
but the following tests are occasionally useful. Into the 
upper part of the test-tube insert a glass rod moistened with 
concentrated hydrochloric acid (that is, with the aqueous 
solution of hydrochloric acid gas conventionally termed 
hydrochloric acid, the Acidam Hydrochloricum of the 
Pharmacopoeia); white fumes of ammonium chloride will 
be produced : — NH3+HC1=NH^C1. Hold a piece of moist 
red litmus-paper in a tube from which ammonia is being 
evolved ; the color will be changed to blue. 

Though ammonium itself cannot be obtained in the free state, 
its compounds are stable. As the foregoing experiment shows, 
ammonia is easily expelled from these compounds by the action 
of the stronger alkalies, caustic 2:>otash, caustic soda, or slaked 
lime. As a useful exercise, the student should here construct 
equations in which ammonium acetate, NH4C.^H3N2, sulphate, 
(NH^)^S04, nitrate, NH4NO3, or any other ammonium salt, is 
supposed to be under examination; also equations representing 
the use of the other hydroxides, KOH or Ca(0H)2. 

2. To a few drops of a solution of an ammonium salt, add 
a drop or two of chloroplatinic acid, H^PtClg; a yellow crys- 
talline precipitate of ammonium chloroplatinate, (NHJ„PtClg, 
will be produced, similar in appearance to the corresponding 
potassium salt, the remarks concerning which {see p. 82) are 
equally applicable to the precipitate under notice. 

0. To a moderately concentrated solution of ammonium salt 
add a saturated solution of sodium bitartrate, and shake well 
or stir the mixture; a white granular precipitate of ammonium 
bitartrate (acid ammonium tartrate) will be formed. 

For data from which to construct an equation representing this 
action, see the remarks and formulae under the analogous potas- 
sium salt (p. 83). 

4. Evaporate a few drops of a solution of an ammonium 
salt to dryness, or place a fragment of a solid ammonium salt 



LITHIUM. 



103 



on a piece of platinum foil, and heat in a flame; the salt is 
readily volatilized, usually with decomposition. As already 
noticed, the salts of potassium and sodium are jixed (i. e., non- 
volatile) under these circumstances, a point of difference of 
which advantage is frequently taken in analysis. A porcelain 
crucible may often be advantageously substituted for platinum 
foil in experiments on volatilization. 

Salts of ammonium with the more complex acid radicals seldom 
volatilize unchanged when heated. The oxalate, when so treated, 
loses its water of crystallization, and at a higher temperature decom- 
poses, yielding carbonic oxide, carbonic anhydride, ammonia gas, 
water, and several organic substances. The phosphate loses water 
and ammonia, and yields a residue of metaphosphoric acid. 

A wire triangle may be used in supporting crucibles (Fig. 21). 
It is made by twisting together each pair of ends of three (5- or 6- 
inch) crossed pieces of wire (Fig. 22). A piece of tobacco-pipe 
stem (about 2 inches) is sometimes placed in the middle of each 
wire before twisting, the transference of any metallic matter to 
the sides of the crucible being thereby prevented (Fig. 23). 



Fig. 21. 



Fig. 22. 



Fig. 23. 




Triangular supports for crucibles. 



LITHIUM : Li. Atomic weight, 6 98. 

Lithium is widely distributed in nature, but is usually in 
minute proportions as compared with other plements. A trace o1 
it may be found in most soils and waters, a certain spring in 
Cornwall containing even considerable quantities as chloride. 

Lithium carbonate, Li.^CO;^, {Lithii Carbonas, U. 8. P.), is a 
white granular powder obtained from the minerals which contain 
lithium — namely, lepidolite (from 'Atirii;, Icpis, a scale, and ?.iQoi\ 
lifhos, a stone, referring to its scaly appearance); triphane (from 
rpeig, treis, three, and (palvo, phaino, I shine) or spodumone (t'rom 
Gnodoco, spodoo, I reduce to ashes, in allusion to its exfoliation in 



104 THE METALLIC RADICALS. 

the blow-pipe flame); and petalite (from -era/.ov, petalon, a leaf, 
referring to its laminated character). Each contains aluminium 
silicate, with potassium and lithium fluoride in the case of Aus- 
trian lepidolite (which is the most abundant source) and sodium 
and lithium silicates in the others. To separate the lithium, 
lepidolite is decomposed by sulphuric acid; alumina, etc., precip- 
itated by ammonia; the filtrated evaporated and the residue 
ignited. The resulting sulphates are dissolved in water and lithium 
carbonate is precipitated by adding a solution of a carbonate. 
The jDreparation of common alum is sometimes made a part of the 
factorv jDrocesses. Lithii Carbona-s, Y. S. P., is soluble in 75 parts 
of water at 25°C. and in 140 at 100° C. 

Lithium citrate {Lithii Cifras, IT. S. P.), is used in medicine. 
It occurs in white deliquescent crystals or powder, prepared 
bv saturating citric acid with lithium carbonate. The crvstals 
have the formula LigCgH-O., 4H2O; dried at 212° F. (100° C), 
LigCgHp,, H,0 (Umney)' 

SLi^CO^ + 2Il,C^-K.O^ = 2Li,CgH,0, + SH^O -f 300^ 

Lithium Citric acid Lithium Water Carbonic 

carbonate citrate anhydride 

Lithium citrate should yield by incineration 52,8 percent, of 
white lithium carbonate. Lithii Citra-s Effervescem, IT. S. P., is 
prepared by mixing lithium citrate with citric and tartaric acids 
and sodium bicarbonate, then heating and stirring until the mixt- 
ure assumes a granular character. 

Other official salts of lithium are Lithii Beiizoas, U. S. P., 
LiC.H.O.,; Lithii Bromidum, U. S. P., LlBr; and Lithii Salicylas, 
U. S. P.,"LiaH.03. 

Lithium urate'^ is more soluble than sodium urate; hence lithium 
preparations are administered to gouty patients in the hope 
(apparently quite unintelligible on any chemical grounds) that 
sodium urate, with which such systems are loaded, may be con- 
verted into lithium urate and removed. 

In its analytical behavior, lithium stands in some respects 
between the alkali-metals potassium and sodium, and the metals 
of the barium group (barium, strontium, and calcium | its hydrox- 
ide, carbonate, and phosphate being only slightly soluble in water. 
Lithium chloroplatinate, Li.PtCl^, is soluble in water and alcohol. 
The atom of lithium, is univalent, Li. 

Analytical Beactions of LJthium Salts. 

^ 1. To a solution of lithium chloride, LiCl (obtained by 
dissolving a few grains of lithium carbonate in dilute hydro- 
chloric acid), add a solution of ordinary sodium phosphate, 
Na.,HPO^, and a little sodium hydroxide, or ammonia water, 

' Urates will be considered subsequently in connection with uric acid. 



LITHIUM. 



105 



and boil. A white crystalline precipitate of lithium phos- 
phate is produced : — 

3LiCl + Na.HPO, + NaOH = Li3P0, + 3NaCl + H^ 

2. Moisten the end of a platinum wire with a solution of 
a lithium salt, and introduce it into the flame of a Bunsen 
burner or spirit-lamp ; a magnificent crimson tinge is im- 
parted to the flame. 

The light thus emitted by incandescent lithium vapor is of a 
purer crimson than that given by strontium. When the flames 
are examined by means of the spectroscope the red rays are, in the 
case of strontium, found to be associated with blue and yellow, 
neither of which is observed in the lithium light. 

Qualitative Analysis. 

With regard to those of the preceding experiments which are 
useful rather as means of detecting the j3resence of potassium, 
sodium, ammonium, and lithium (the so-called ^'tests''), than as 
illustrating the preparation of salts, the student should proceed to 
apply them to certain solutions of any of the salts of these metallic 
radicals with the view of ascertaining which radical is present; 
that is, proceed to practical a?ialysis.'^ A little thought will enable 
him to apply the reactions in the most suitable order and to the 
best advantage for the contemplated purpose; but the following 
arrangements are perhaps as good as can be devised : — 



Directions for applying the analytical reactions 
described in the foregoing paragraphs to the 
analysis of an aqueous solution a salt of one of 
the metallic radicals, potassium, sodium, ammonium, 

LITHIUM. 

To a small portion of the solution to be examined, in a 
test-tube, add sodium hydroxide test solution, and warm the 

^ Such solutions are prepared in educational laboratories by a tutor. 
They should, under other circumstances, be mixed by a friend, as it is 
not desirable for the student to know previously what is contained in the 
substance he is about to analyze. 

The analysis of solutions containing only one salt serves to impress 
the memory with the characteristic tests for the various metallic and 
other radicals, and familiarize the mind Avith chemical principles. Medi- 
cal students seldom have time to go farther than tliis. Move thorough 
analytical and general chemical knowledge is only acquired by working 
on such mixtures of substances as are met with in actual practice, begin- 
ning with solutions which may contain any or all of the members of a 
group. Hence in this Manual two tahles of short analytical directions are 
given under each group. Pluirmaceutical students should follow the set-ond. 



106 THE METALLIC RADICALS. 

mixture ; the odor of ammonia gas reveals the presence of an 
ammonium salt. 

To a few drops of the solution, apply the bismuth thio- 
sulphate test for potassium (p. 83); a yellow precipitate 
indicates the presence of potassium. Potassium may also be 
detected by means of the chloroplatinic acid test, but only in 
the known absence of ammonium salts. 

The flame-test is sufficient for the recognition of sodium or 
of lithium. 

Directions for applying the analytical reactions 
described in the foregoing paragraphs to the 
analysis of an aqueous solution of salts of one or 
more of the alkali-metals. 

I. In cases when it is not necessary to effect actual separation 
of the metallic radicals present, the examination of the solution 
may best be carried out by making special tests for each of them 
as below : — 

To a small portion of the solution in a test-tube, add sodium 
hydroxide and warm the mixture; the odor of ammonia reveals 
the presence of an ammonium salt. 

Apply the bismuth thiosulphate test for potassium to a few 
drops of the solution (p. 83). The formation of a yellow pre- 
cipitate indicates the presence of a potassium salt. ^ 

To another portion of the solution add sodium phosphate and 
then ammonia water until the liquid, after shaking, smells of 
ammonia, and boil. The formation of a white precipitate indi- 
cates the presence of a lithium salt. Test for lithium also by the 
flame-test. 

The flame-test is suflicient for the recognition of sodium unless it is 
present in small quantity along with much lithium. In such a case 
the spectroscope may be employed. Traces of lithium may also be 
detected in presence of much sodium by means of the spectroscope. 

Note on the flame-test. — When the violet tint imparted to the 
flame by potassium salts is masked by the intense yellow color 
due to sodium, it may still be recognized, in the absence of lithium 
salts, if the flame be observed through a piece of dark-blue glass, 
a medium which absorbs the yellow rays of light but allows the 
violet rays to pass. It is not safe to examine a solution for 
potassium by the flame-test in the known presence of lithium salts. 

II. Should it be necessary actually to separate the metallic 
radicals from one another, the analysis may be carried out ac- 
cording to the following method : 

* If an ammonium salt be present, it is desirable to get rid of it as 
described under II., before applying tbis test for potassium. 



LITHIUM. 



107 



Commence by testing a small portion of the solution for an 
ammonium salt; if it be present it must be got rid of prior to 
testing for (and if present, removing) potassium as chloropla- 
tinate. Evaporate the remainder of the original solution to dry- 
ness in a small basin, transfer the solid residue, by instalments if 
necessary, to a porcelain crucible, and heat the latter to low red- 
ness until white fumes, due to the decomposition of ammonium 
salts, no longer escape (see Fig. 19). This operation should be 
conducted in a fume-cupboard, to avoid contamination of the air of 
the laboratory. When the crucible has cooled, dissolve the solid 
residue in a small quantity of hot water, filter if necessary, add 
excess of chloroplatinic acid (i. e., add sufficient of the reagent to 
convert the whole of the alkali-metals present into chloropla- 
tinates) and evaporate to dryness on a water-bath, or at any rate 
at a temperature not exceeding 100° C. Digest the residue for 
some time with alcohol, and filter : — 



Residue. — A heavy 


Filtrate.— May contain sodium and lithium 


yellow powder con- 


chloroplatinates, with excess of chloroplatinic 


sisting of potassium 


acid. Evaporate or distil off the alcohol, and 


chloroplatinate. 


heat to redness the brown solid which remains. 


K2PtCl6. Wash with 


Treat the residue with hot water, and filter : 


alcohol ; dry ; trans- 




fer to a porcelain 


Residue. — 


Filtrate. — May contain NaCl 1 


crucible, and heat 


Consists of 


and LiCl. Evaporate to dry- 1 


gradually up to red- 


platinum. 


ness. Treat repeatedly with 1 


ness. Treat the resi- 




alcohol, filtering each instal- 1 


due with hot water, 




ment. 1 


and filter : 




1 






Residue. — 


Filtrate.— May 


Residue.^ 


Filtrate.— 




NaCl ; con- 


contain LiCl. 


Consists 


Contains 




firm by 


Apply flame-test. 


of 


potassium 




flame-test. 




platinum. 


chloride. 

Comfirm 

potassium 

by the 

flame-test. 









Note on Nomenclature. — The operations of evaporation and 
heating to redness, commonly termed i(/nition, are frequently 
necessary in analysis, and are usually conducted in the above 
manner. If vegetable or animal matter be present also, carbon 
is set free, and ignition is accompanied by carl)onization; the 
material is said to char. When all carbonaceous nuitter is burnt 
off (the crucible being slightly inclined and its cover removed to 
facilitate combustion), and mineral matter, or ash, alone remains, 
the operation of incineration has been effected. 



108 THE METALLIC RADICALS. 

Note on the Classification of the Elements. — The compounds of 
potassium, sodium, ammonium, and lithium, have many analogies. 
The carbonates, phosphates, and other common salts are soluble 
in water, except lithium carbonate and phosphate, which are only 
sparingly soluble. Atoms of the metallic radicals are univalent 
— that is, each displaces or is displaced by one atom of hydrogen. 
In fact, these radicals constitute by their similarity in properties a 
distinct group or family. All the elements thus naturally fall into 
classes — a fact that should constantly be borne in mind, and 
evidence of which should always be sought. It would be impos- 
sible for the memory to retain the details of Chemistry with- 
out a system of classification and leading principles. Classifi- 
cation is also an important feature in the art as well as in the 
science of Chemistry; for without it practical analysis could not be 
undertaken. The classification adopted in this volume is founded 
on the quantivalence of the elements (or radicals) and on their 
analytical and general relations. 



QUESTIONS AND EXERCISES. 

Why are ammonium salts classed with those of potassium and sodium ? 
Mention the sources of the ammonium salts. — Describe the characters 
of Ammonium Chloride. — Give the formula of Ammonium Sulphate. — 
Adduce evidence of the existence of Ammonium. — How is Ammonia 
water prepared? — How is the official Solution of Ammonium Acetate 
prepared? — What is the composition of commercial Ammonium Carbon- 
ate? — Define sublimation. — What ammonium salt is contained in Spiritus 
Ammonix Aromaticus, U. S. P. ? — Give diagrams or equations illustrating 
the formation of Ammonium Citrate (from hydroxide and from carbon- 
ate), Phosphate, and Benzoate. — Give the formula of Ammonium Oxa- 
late. — How is ammonium hydroxide converted into sulphide? — Describe 
the preparation of Hydrogen Sulphide. — Enumerate and explain the 
tests for ammonium. — How is potassium detected in a solution in which 
ammonium has been found? — Give equations illustrating the action of 
sodium hydroxide on ammonium acetate; potassium hydroxide on 
ammonium sulphate ; and calcium hydroxide on ammonium nitrate. — 
Name the sources and official compounds of lithium. — Explain the forma- 
tion of lithium citrate. — On what chemical hypothesis are lithium 
compounds administered to gouty patients? — What are the chief tests for 
lithium ? — Describe the analysis of an aqueous liquid containing salts of 
potassium, sodium, ammonium and lithium. — What meanings are com- 
monly assigned to the terms evaporation, ignition, carbonization, and 
incineration ? — Write a short article descriptive of the analogies of potas- 
sium, sodium, ammonium and lithium and their compounds. 



BARIUM, STRONTIUM, CALCIUM, MAGNESIUM. 

These four elements have many analogies. Their atoms are 
bivalent— Ba--, Sr*-, Ca**, Me:--. 



BARIUM. 



109 



BARIUM: Ba. Atomic weight, 136.4. 



It is the analytical reactions of this metal which are of chief 
interest to the student of pharmacy. Barium nitrate, Ba(N03)2, 
and chloride, BaCl2,2H20 (''Barium Chloride Test Solution," 
U. S. P., contains 1 in 10 of water) are the soluble salts in common 
use in analysis. These and other salts are made by dissolving the 
native carbonate, BaCOj (the mineral witherite) in acids, or by 
heating the other common natural compound of barium, the sul- 
phate {Jieavy whiU or heavy spar, BaS04) with coal, which yields 
barium sulphide, BaS (BaS04+4C=4CO+BaS), and treating this 
with appropriate acids. When the nitrate is strongly heated, it 
decomposes, yielding barium oxide or baryta, BaO. By intensely 
heating a mixture of barium sulphate and carbon in the electric 
furnace, barium oxide mixed with a small proportion of sulphide 
is now prepared on a large scale. Barytha, on being moistened, 
unites with the elements of water with the evolution of much 
heat, and yields barium hydroxide, Ba(0H)2. The latter is toler- 
ably soluble, giving baryta water; and from this solution crystals 
of barium hydroxide, Ba(0H)2, 8H2O, are obtained on evaporation 
Barium hydroxide is largely used in the refining of sugar. 

Bai'ium Dioxide, Ba02, is formed in passing air over barium 
oxide heated to about 600° C. At a somewhat higher tempera- 
ture, oxygen is evolved and barium oxide remains. This is 
Boussingault' s old process ; but, after a time, the barium 'oxide 
loses its power of combining with additional oxygen. If the air 
be freed from carbonic anhydride, and the dioxide be not exposed 
to a much higher temperature than 800°C., the barium oxide can 
be used over and over again. The air is passed over it under in- 
creased pressure, and gives rise to the formation of the dioxide. 
The air is then turned off, and the additional oxygen is given up 
again when the pressure is sufficiently reduced by means of air- 
pumps. 

Hydrogen Dioxide. — By the action of a dilute acid, barium 
dioxide yields a solution of hydrogen dioxide, H2O2, formerly 
called oxygenated water. An aqueous solution of hydrogen dioxide 
which yields (by the decomposition of the dioxide) ten times its 
volume of oxygen, is the official Aqua Hydrogenii Dioxidi, U. S. P. 
When this solution is mixed with a sufficiency of diluted sulphuric 
acid, and solution of potassium permanganate is added in excess, 
the dioxide is completely decomposed, with evoluting oxygen : — 

5H2O2 + 2KMnO, + 3H2SO, = 5O2 + 8H2O + K2SO4 + 2Mn8(\ 

One-half of the oxygen comes from the dioxide and one-half from 
the permanganate. The dioxide readily yields oxygen to many 
inorganic and organic substances. 



110 THE METALLIC RADICALS. 

Analytical Beactmis of Barium Salts. 

1. To the aqueous solution of any soluble barium salt (nitrate or 
chloride, for example) add dilute sulphuric acid ; a white precipi- 
tate is obtained. Set the test-tube aside for two or three minutes, 
and when some of the ^precipitate has fallen to the bottom, pour 
away the supernatant liquid, wash the precipitate by adding water, 
shaking, setting aside, and again decanting; and then add moder- 
ately concentrated nitric acid, and boil; the precipitate is insol- 
uble. The precipitate is at once produced by the addition of a 
solution of calcium sulphate or other soluble sulphate. 

The production of a white precipitate by sulphuric acid or other 
sulphate, insoluble even in hot nitric acid, is highly characteristic 
of barium. The precipitate consists of barium sulphate, BaSO^. 

2. To a solution of barium salt add solution of potassium chro- 
mate, K.^CrO^ ; a pale-yellow precipitate of barium chromate, 
BaCrO^, is immediately formed. Add acetic acid to a portion ; it 
is insoluble. Add hydrochloric or nitric acid to another portion ; 
it dissolves. 

Potassium dichromate or anhydrochromate, KgCrO^, CrOg, or 
K2Cr20^, must not be used in this reaction, otherwise the barium 
will be only partially precipitated, as the dichromate gives rise to 
the formation of free acid, in which barium chromate is to some 
extent soluble: — 

K^CrO^CrOa + 2BaCl, + H,0 = 2BaCrO, + 2KC1 -{- 2HC1. 

Other Analyticial Reactions.^To a solution of a barium 
salt add a solution of a carbonate (ammonium carbonate, 
(NH^)2C03, will generally be rather more useful than the 
others); a white precipitate of barium carbonate, BaCO.^, is 
formed. To another portion of the solution add an alkali- 
metal phosphate (sodium phosphate, Na^HPO^, is the most 
common of these chemically analogous salts, but ammonium 
phosphate (NHj,,HPO^, is often used in preference); white 
barium hydrogen phosphate, BaHPO^, is precipitated, insol- 
uble in pure water, but slightly soluble in aqueous solutions 
of some salts, and readily soluble even in acetic and other 
weak acids. To another portion add ammonium oxalate, 
(NHJ^CO^; white barium oxalate, BaC.,0^, is precipitated, 
soluble in dilute mineral acids, and sparingly so in acetic 
acid. Barium salts, moistened with hydrochloric acid, impart 
a greenish color to a Bunsen flame or spirit-lamp flame. 

Memoranchan. — Good practice will be found in writing out 
equations to re])resent each of the foregoing reactions. 

Antidotes. — In cases of i^oisoning by soluble barium salts, obvious 



STRONTIUM. Ill 

antidotes would be solution of alum or of such sulphates as those 
of magnesium (Epsom salt) and sodium (Glauber's salt). 



QUESTIONS AND EXERCISES. 

What is the valency of barium? — Write the formulge of barium oxide, 
hydroxide, chloride, nitrate and sulphate; and state how the substances 
are prepared. — Describe the preparation of hydrogen peroxide. — Which 
of the tests for barium ai*e most characteristic? — Give equations for the 
reactions. — Name the antidote in cases of poisoning by soluble barium 
salts and explain its action. 



STRONTIUM : Sr. Atomic weight, 86.94. 

Occurrence. — Strontium compounds are not abundant in nature; 
yet the carbonate, SrCO.^, known as strontianite, and the sulphate, 
SrSO^, known as celestine (from cmluin, the sky, in allusion to its 
occasional bluish color), are by no means rare minerals. 

Salts of Strontium are occasionally emj^loyed in medicine, the 
following being official in the United States Pharmacopoeia: — 
Strontii Bromidum, SrBr2,6H20; Strontii lodidum, Srig, 6H0O; 
Strontii Salicylas, '^v{Q^H^0'^.22iL,f). The compounds of this 
metal are, however, chiefly used by firework manufacturers in 
preparing "red fire." Strontium hydroxide, like barium hy- 
droxide, is much used in sugar-refining. Strontium salts impart 
a crimson color to the flame. Strontium nitrate, Sr(NO.^).^, is the 
most suitable strontium salt to use in making pyrotechnic mixtures, 
its oxygen causing vigorous combustion when the salt is mixed 
with charcoal, sulphur, etc., and heated. This salt may be 
obtained by dissolving the carbonate in nitric acid; a method 
which is appropriate for the preparation of other strontium salts 
if the corresponding acids are employed. Strontium salts may 
also be prepared from the cheaper strontium sulphate, SrSO^, by 
strongly heating this with carbon to convert it into sulphide, SrS, 
and then dissolving the latter in the appropriate acids. Strontium 
sulphate is very sparingly soluble in water. 

Analytical Reactions of ^Strontium Salts. 

1. To a solution of strontium nitrate or chloride add 
ammonium carbonate; a white precipitate of strontium car- 
bonate, SrCO.^, is produced. 

2. To a solution of a strontium salt add hio-hly dilute sul- 
phuric acid, or an equally dilute solution of any sulphate 
(that of calcium, for example); a white precipitate of strontium 
sulphate, SrSo^, is produced. The formation of this procipi- 



112 THE METALLIC RADICALS. 

tate is promoted by stirring and by setting the liquid aside 
for some time. (Barium salts give an immediate precipitate 
under similar circumstances.) 

3. To a dilute solution of a strontium salt add potassium 
cliromate ; no precipitate is produced unless the mixture is 
allowed to stand for some time, or is boiled. 

Barium may be separated from the strontium by means of 
potassium chromate, this reagent at once precipitating barium 
from aqueous or acetic acid solutions. The value of the reaction 
is enchanced if acetic acid or ammonium acetate be present, stron- 
tium chromate being far more soluble in such fluids than in water 
(Ransom). It is also more soluble in cold than in hot solutions. 

4. Moisten the end of a platinum wire with a solution of a 
strontium salt and hold it in the Bunsen flame; a crimson 
color is imparted to the flame. 

Other Analytical Reactions. — Alkali-metal phosphates and 
oxalates give white insoluble precipitates with strontium salts 
as with barium (and also with calcium) salts. 

CALCIUM : Ca. Atomic weight, 39.8 . 

Occurrence, etc. — Calcium compounds form a large proportion 
of the crust of our earth. Calcium carbonate is met with as chalk, 
marble, limestone, calc-spar, etc.; the sulphate as gypsum and 
alabaster; the silicate in many minerals; calcium fluoride as fluor- 
spar. The phosphate is also a common mineral. Plaster-of-Paris, 
(Caicii Sulphas Exsiccatus, U. S. P.), is gypsum from which the 
water of crystallization has been driven away by heating to a 
temperature of dull redness. The element itself is only isolated 
with great difficulty. Its melting point is 760° C. ; its sp. gr. 
1.85 at 15.5° C. 

Calcium Chloride. 

Experiment 1. To some hydrochloric acid add calcium car- 
bonate (Chalk, or the purer form, white marble), CaCO.j, 
until eflfervescence ceases ; Alter ; solution of calcium chloride, 
CaCL, a common soluble calcium salt is formed. 



CaCo3 + 2HC1 = 


CaCl, + 


H^O 


+ CO3 


Calcium Hydrochloric 


Calcium 


Water 


Carbonic 


carbonate acid 


chloride 




anhydride 



This solution may be obtained quite neutral by well boiling 
before filtering off the excess of marble. 

Solution of calcium chloride evaporated to a syrupy consistence 



CALCIUM. 113 

yields crystals (CaCl^, 6H2O). These are extremely deliquescent. 
The solution, evaporated to dryness, and the white residue heated 
to about 392° F. (200° C), gives solid calcium chloride, CaCl^, 
2H.,0, in a porous form. The resulting lumps are used for drying 
gases and for freeing certain liquids from water. By fusion at a 
low red heat the anhydrous chloride CaCl,^, {Calcii Chloridum, 
U. S. P.), is produced. Calcium chloride is soluble in alcohol. 

Marble often contains ferrous carbonate, FeCO^ which in 
the above process becomes converted into ferrous chloride, 
rendering the calcium impure : — 

FeCO., + 2HC1 = FeCl, + H,0 + CO^ 

Ferrous Hydrochloric Ferrous Water Carbonic 

carbonate acid claloride anhydride 

If pure calcium chloride be required, a few drops of the 
solution should be poured into a test-tube or beaker, diluted 
with water, and examined for iron (by adding ammonium 
hydrosulphide, which gives a black precipitate with iron 
salts), and if the latter is present, calcium hypochlorite (in 
the form of chlorinated lime) and slaked lime should be added 
to the remainder of the liquid, and the whole boiled for a 
few minutes. The iron is precipitated as ferric hydroxide, 
and is filtered off : — 

4FeCl, + Ca(C10)2 + 4Ca(OH)2 + 211,0 = 4Fe(OH)3 + 5CaCl, 

Ferrous Calcium Calcium Water Ferric Calcium 

chloride hypochlorite hydroxide hydroxide chloride 

The solution of calcium chloride so obtained may contain 
some calcium chlorate. On adding excess of ammonium car- 
bonate and heating gently, then washing the precipitate 
thoroughly with hot water {see p. 114) and redissolving it 
in hydrochloric acid, a pure solution of calcium chloride may 
be obtained. 

This process may be imitated on the small scale after 
adding a minute piece of iron to a fragment of the marble 
before dissolving in acid. 

Calcium bromide, {Calcii Bromidwn, U. S. P.), is also 
official. 

Calcium Oxide. Quicklime. Caustic Lime. 

Experiment 2. — Place a small piece of chalk in a strong- 
fire or furnace, and heat until a fragment, chipped ofi' and 
cooled, does not effervesce on the addition of acid ; lime, CaO, 
{Calx, U. S. P.), remainSo 

8 



114 THE METALLIC RADICALS. 



C'aCO, = 


CaO + CO2 


Calcium 


Calcium Carbonic 


carbonate (chalk) 


oxide (lime) anhydride 



Lime-kilns. — On a large scale the above operation is carried 
on in what are termed lime-kilns (kiln, Saxon, cijln, from ojlene, 
a furnace). 

Calcium Hydroxide. Slaked Lime. 

Experiment 3. — When the quicklime prepared in the pre- 
ceding experiment is cold, add to it about half its weight of 
water, and notice the evolution of steam and the other 
evidence of energetic chemical action; the product is slaked 
lime, calcium hydroxide, Ca^OH)^ with whatever slight 
natural impurities the lime may contain. The slaking of hard 
or "stony" lime may be accelerated by using hot water. 

CaO + H,0 =: Ca(OH), 
Lime Water Calcium hydro'xide 

Lime-Water — Place the calcium hydroxide (washed with 
a little water to remove traces of soluble salts) in about a 
hundred times its weight of water, and shake frequently; 
in a short time a satured solution, known as lime-water, 
(^Liquor Calcis, U. S. P.), results. It contaius about 13 
grains of calcium hydroxide, Ca( OH), ^, equivalent to about 
10 grains of lime, (CaO), in one point at 60° F. (15.5° C). 
At higher temperatures less is dissolved. 

Saccharated Solution of Lime. — Slaked lime is much more 
soluble in aqueous solution of sugar than in pure water. Syrup 
of lime, {Sijrupus Calcis, U. S. P.), is such a solution. It is a 
more efficient precipitant of hydroxides, carbonates, and phos- 
phates than lime-water. 

Solutions of calcium hydroxide absorb carbonic anhydride on 
exposure to air, a semi-crystalline precipitate of calcium carbon- 
ate being deposited. "When the saccharated solution is heated, 
there is precipitated a compound consisting of three molecules of 
lime with one of sugar. When it is treely exposed to air, oxy- 
gen is absorbed, and the solution becomes colored. 

Calcium Carbonate. 

Experiment 4. — To a solution of calcium chloride add excess 
of sodium carbonate, or about 13 parts of the carbonate to 5 
of the anhydrous chloride ; a white precipitate of calcium car- 
bonate, CaCOg, (Calcii Carbouas PrcBcipitatus, U. S. P.), is 



CALCIUM. 



115 



produced. If the solution of the salts be heated before admix- 
ture, and the whole be set aside for a short time, the particles 
assume a finely granular or slightly crystalline character to 
a greater extent than when cold water is used. 



CaCl, 


+ NaCOg : 


- CaC03 


+ 


2NaCl 


Calcium 


Sodium 


Calcium 




Sodium 


chloride 


. carbonate 


carbonate 




chloride 



Collect and purify this so-called Precipitated Calcium Car- 
bonate, by pouring the mixture into a filter-paper supported by 
a funnel, and when the liquid has passed through the filter, 
pour w^ater over the precipitate three or four times, until the 
whole of the sodium chloride is washed away. This operation 
is termed washing a jjrecipitate. When dried by aid of a 
ivater-bath (p. 118) or other means, the precipitate is ready for 
use. It is not only somew^ hat purer than the average samples 
of natural chalk or "prepared chalk" (see p. 117), but it is 
less liable to aggregate, and on account of its physical charac- 
teristics is far superior as a constituent of dentifrices. 

Filter-paper or bibulous paper (from bibo, 1 drink), is simply 
good unsized paper made from the best white rags — white blot- 
ting-paper, in fact, of unusually good quality. Students' or ana- 
lysts' filters, on which to collect precipitates, are circular jDieces 
{a, Fig. 24), of this paper, from three to six inches in diameter, 

Fig. 24. 




Construction of paper filters. 



twice folded {b, c), and then opened out so as to form a hollow 
cone (d). The cone is supported by a glass or earthenware fun- 
nel. Square pieces of filter-paper should be rounded by scissors 
after twice folding. If this is not done, angular portions of the 
paper project above the liquid in the filter, and if a spirituous or 
other volatile liquid is being passed through such a paper, much 
of the liquid will be wasted by evaporation from tlie unnecessarily 
large surface exposed. 

Paper filters of large size are n})t to break at the point of the 
cone. This may be prevented, and the rate of filtration nnich 
accelerated, by supporting the paper cone in a cone of nuisliu. 



116 



THE METALLIC RADICALS. 



Fig. 25. 



Wash-bottle. — Precipitates are best washed by means of a fine 
jet of water directed on to the different parts of the filter. A 
common narrow-necked bottle, of about half-pint capacity, is 
fitted with a cork; two holes are bored through 
the cork, the one for a glass tube which reaches 
to the bottom of the bottle and is bent exter- 
nally to a slight acute angle, the other for a 
tube bent to a slightly obtuse angle, the inner 
arm terminating just inside the bottle. The 
outer arms may be about three inches in length. 
The extremity of the outer arm of the longer 
tube should be previously drawn out to a fine 
capillary opening by holding the original tube 
(before bending) in a flame, and, when soft, 
slowly pulling the two ends apart from each 
other until the softened portion is reduced to 
the diameter of a knitting-needle. The tube 
is now cut at the narrow part by means of a file, and the sharp 
edge rounded ofi" by placing it in a flame for a second or two. 
The outer extremity of the shorter tube should also be rounded 
off" in the flame. The apparatus being put together and the bottle 
nearly filled with water, air from the lungs, blown through the 
short tube, forces water out in a fine stream at the ca^^illary orifice. 
For a hot-icater loash-hottle (Fig. 25) the tubes and cork are fitted 
to a flask which may be heated over a Bunsen burner or on a 
water-bath (p. 118). Fine twine wound closely around the neck of 
the flask forms a suitable non-conducting protection for the hand 
of the operator. 




Hot-water wash- 
bottle. 



Fig. 26. 



Fig. 27. 



Fig. 28. 




Decantation. 



Decantation. 



Siphon in action. 



Decantation. — Precipitates may also be washed by allowing 
them to settle, pouringoff'thesupernatant liquid (Fig. 26) agitating 
with water, again allowing to settle, and so on. This is washing 



CALCIUM. 



117 



by decant afion (de, from; canthus, an edge). If the stream of 
liquid exhibits any tendency to run down the outer side of the 
vessel during decantation, it should be guided by a glass rod 
placed against the point where the stream emerges (Fig. 27). 

If the vessel be too large to handle with convenience, the liquid 
may be drawn off by means of a siphon, as shown in Fig. 28. 

Prepared chalk, [Grata Prceparata, U. S. P.), is merely washed 
chalk or whitifig, but in pharmacy, fashion demands that the chalk 
be in little conical lumps, about the size of thimbles, instead of 
in the larger rolls characteristic of whiting. Its powder is amor- 
phous. 

If either the precipitated calcium carbonate, or the prepared 
chalk, contains alumina, magnesium salts, iron oxide, or phos- 
phates, its solution in acid, evaporated to dryness, and redissolved 
in water, will yield a precipitate of hydroxides or phosphates on 
the addition of syrup of lime. 



Calcium Phosphate. 

Experiment 5. — Digest bone-ash (bones burnt in an open 
crucible with free access of air until all animal and carbo- 
naceous matter has been removed, and a residue of impure 
calcium phosphate is left), with twice its weight of hydro- 
chloric acid (diluted with four times its volume of water) in 
a test-tube or larger vessel ; the phosphate is dissolved. 

CagfPO^X + 4HC1 = CaHJHOJ, + 2CaCl2 

Caicium Hydrochloric Acid calcium Calcium 

phosphate acid phosphate chloride 

Dilute the solution with water, boil, filter, and when cold, 
add excess of ammonia solution ; the calcium phosphate, now 
practically pure, ( Caleii Phosphas Prcecipitatus, U. S. P.), is 
reprecipitated as a light white amorphous powder. After 
well washing, the precipitate should be dried over a water- 
bath (see p. 118), or at a temperature not exceeding 212° F. 
(100° C), to prevent undue aggregation of the particles. 



CaH,(PO,), 4- 2CaCl2 


+ 4NH3 == 


Ca3(P0,), + 4NH,C1 


Acid calcium Calcium 


Ammonia 


Calcium Ammonium 


phosphate chloride 




phosphate chloride 



Bone-ash or bone-earth contains small quantities of calcium car- 
bonate and sulphide. These are decomposed in the above process 
by the acid, calcium chloride being formed; on boiling the mix- 
ture, carbonic anhydride and hydrogen sulphide are evolved. Any 
carbonaceous or siliceous matter, etc., is removed by tiltration. 
In bones, the calcium phosphate is always accompanied by a small 
quantity of an allied substance, magnesium phosphate, which is 



118 THE METALLIC RADICALS. 

not removed by the process described above. Bone-ash also con- 
tains a trace of cak^iuni fluoride, OaF.^. 

Calcium phosphate is generally prepared by the interaction of 
calcium chloride, sodium phosphate, and ammonia, the resulting 
precipitate being washed with cold water. 

Calcium Hypophosphite, {Calcii Ilypophosphis, U. S. P.), is 
oflBcial. 

A Water-bath for the evaporation of liquids or for drying moist 
solidsat a temperature below 212° F. (100° C), is an iron, tin, or 
earthenware pan, the mouth of which can be narrowed by iron or 
tin diaphragms of various sizes, so as to adapt it to the diameters 
of basins or plates. {See Fig. 18, p. 76). In the British Pharma- 
copajia, ''when a water-bath is directed to be used, it is to be 
understood that this term refers to an apparatus by means of which 
water or its vapor, at a temperature not exceeding 212° F. 
(100° C), is applied to the outer surface of a vessel containing 
the substaiice to be heated, which substance may thus be sub- 
jected to a heat near to, but necessarily below, that of 212° F. 
(100° C.)." Evaporation in vacuo is performed by simply placing 
the vessel of liquid over, or by the side of, a small vessel contain- 
ing concentrated sulphuric acid or other absorbent of moisture, on 
the plate of an air-pump, covering with a capacious glass hood or 
"receiver," and exhausting. 

Sodium Phosphate. — Ordinary sodium phosphate, Na2HP0^, 
I2H2O, (Sodii Phosphas, U. S. P.), is prepared from calcium 
phosphate as follows : — Mix in a mortar, 3 ounces of ground 
bone-earth with 1 fluidounce of sulphuric acid ; set aside for 
twenty-four hours to allow the interaction to take place ; add 
about 8 ounces of water and put in a warm place for two 
days, a little warm water being added to make up for that 
lost by evaporation ; stir in another 3 ounces of water, warm 
th^ whole for a short time, filter, and wash the residual cal- 
cium sulphate on the filter in order to remove adhering acid 
calcium phosphate; concentrate the filtrate (i. e., the liquid 
which has passed through the filter), to about 3 ounces, and 
filter again if necessary. To the hot solution, which con- 
tains acid calcium phosphate, add solution of sodium carbon- 
ate (preparated from about 4 J ounces of the crystallized salt) 
until a precipitate (calcium hydrogen phosphate, CaHPO^) no 
longer forms, and the liquid is faintly alkaline ; filter, evapo- 
rate, and set aside to crystallize. The following equations show 
the two decompositions which occur during the operations : — 

Ca,(POJ, 

Calcium 

phosphate 



2H,S0, = 


= CaH,(POj, 


+ 


2CaS0, 


Sulphuric 


Acid calcium 




Calcium 


acid 


phosphate 




sulphate 



CALCIUM. 



119 



CaH,(P0,)2 

Acid calcium 
pliosphate 



Sodium 
carbonate 



Na^HPO, 

Sodium 
phosphate 



H,0 

Water 



- CO2 + CaHPO^ 

Carbonic Calcium 
anhydride hydrogen 
phosphate 



Sodium phosphate crystallizes in transparent colorless monoclinic 
prisms, eiSorescent, having an alkaline reaction and a saline taste. 
One part in ten of water constitutes ''Sodium Phosphate Test 
Solution," U. S. P. The crystals effloresce rapidly in the air 
until nearly half the water has escaped, and a salt is obtained 
which has a permanent composition represented by the formula, 
NaailPO^, TH^O. Another sodium phosphate (sodium dihydrogen 
phosphate), NaH2P04,H20, is obtained by mixing solutions of 
phosphoric acid and sodium carbonate in the right proportions, 
evaporating the mixed solution and setting it aside to crystallize. 

Calcium Hypochlorite. 

Experiment 6. — Pass chlorine, generated from black man- 
ganese oxide and hydrochloric acid, as already described, 
over damped slaked lime contained in a piece of wide tubing, 
outlet end of which is connected with a tube leading into a 
fume-cupboard. The product Chlorinated Lime, ( Calx 
Chlorinata, U. S. P.), is ordinary bleaching-powder, a com- 
pound of calcium hypochlorite and chloride, mixed with a 
quantity of unchanged calcium hydroxide. It is commonly, 
but improperly, called chloride of lime, and is one of the 
most efficient of known disinfectants. 



MnO/ 

Black man- 
ganese oxide 



4HC1 = 

Hydrochloric 
acid 



2Ca(OH)2 + 2GI2 

Calcium Chlorine 

hydroxide 



MnCl^ 

Manga nous 

chloride 

2H,0 

Water 



+ 2H,0 -f CI, 

Water Chlorine 



-f CaCl^O^, CaCl^ 

Calcium Calcium 
hypochlorite chloride 



Chlorinated lime exposed to air and moisture, as in disinfecting 
the atmosphere of sick-rooms, slowly yields hypochlorus acid, 
HCIO, calcium carbonate being formed at the same time. Free 
hypochlorus acid soon breaks up into water, chloric acid, HCIO3, 
and free chlorine. Chloric acid is also unstable, decomposing 
into oxygen, chlorine, water and perchloric acid, HCIO^. The 
small quantity of hypochlorus acid diffused through an apartment 
when bleaching-powder is exposed, thus yields fourteen-fifteenth s 
of its chlorine in the form of chlorine gas. 

Constitution of bleaching-powder. — Treated with alcohol, bleach- 
ing-powder does not yield its calcium chloride to the solvent ; 
hence the powder is not a mere mixture of calcium chloride and 
liypochloritc : water, also does not dissolve out first one salt and 



120 THE METALLIC RADICALS. 

then the other, but together, in the molecular proportions of the 
formula, p. 119. On the other hand, when the aqueous solution 
is cooled, or evaporated in vacuo, crystals are obtained which 
Kingzett has shown to be nearly pure calcium hypochlorite, the 
solution containing calcium chloride. While the former fact 
indicates that the powder is a compound and not a mere mixture, 
the latter indicates that it is a feeble compound — an adhesion of 
molecules of hypochlorite and chloride, as shown in the equation, 
rather than any closer or more intimate combination of atoms. 
If it be regarded as a single rather than a double salt, then 
the following formula (Odling) may be employed, CaOCl^, or 

^^ [ CIO 

Bleaching-liquor. — Digest chlorinated lime in water, in 
which the bleaching compound is soluble. Filter from un- 
dissolved lime, etc., and test the bleaching powers of the clear 
liquid by adding a few drops to a decoction of logwood 
slightly acidulated. 

Experiment 7. — Mix a little powdered wood charcoal with 
three or four times its weight of gypsum, and heat to redness 
in a crucible. Some of the calcium sulphate is reduced to 
sulphide, CaS, with production of carbonic anhydride and car- 
bonic oxide. If the product contains not less than 60 per- 
cent, of calcium sulphide, it is the official Sulphurated Lime 
(Calx Sulphurata, U. S. P.). 

Official test. — If 1 Gm. be mixed with a cold solution of 2.08 
Gm. of cupric sulphate in 50 cubic centimetres of water, and, 
after the addition of a little hydrochloric acid, the mixture be well 
stirred and heated on a water-bath until all action has ceased and 
then filtered, the filtrate should give no color on addition of ex- 
cess of ammonia water (presence of at least 60 percent, of pure 
calcium sulphide). 

The explanation of the mode of this test is as folloW'S : — Cupric 
sulphate and calcium sulphide interact in the presence of the acid, 
giving insoluble cupric sulphide and calcium sulphate, thus : — 
CuSO,-fCaS=CuS+CaSO,. 

On adding up the atomic weights or the constituent elements 
of crystallized cupric sulphate, 247.85 will be found to be the 
formula weight; while CaS will similarly represent 71.53 parts. 
As 247.85 is to 71.63, so (approximately) is 14 to 4. But only 
half of the sulphurated lime is calcium sulphide ; therefore 8 grains 
of such sulphurated lime will interact with 14 of cupric sulphate. 
If the 8 grains are below the stated strength, then they will not 
attack the whole of the 14 grains of cupric salt, and, in that 
ammonia water (or potassium ferrocyanide) will reveal copper in 
the filtered liquid. 



CALCIUM. 121 

Calcium Gummate. 

Calcium Gummate is the only official calcium salt that remains 
to be noticed. This compound is, in short, arabiii, the ordinary 
Gum Acacia or Gum Arabic (Acacia, U. S. P.). A solution of 
gum arable in water yields a white precipitate of calcium oxalate 
on the addition of solution of ammonium oxalate ; or a piece of 
gum incinerated in a porcelain crucible yields a calcareous residue, 
which, when dissolved in a dilute acid, affords characteristic 
reactions with any of the analytical tests for calcium salts, de- 
scribed further on. In some specimens of gum arable a portion of 
the calcium is displaced by an equivalent quantity of potassium or 
magnesium. The gummic or arable radical may be precipitated 
as opaque gelatinous lead gummate by the addition of a solution of 
lead subacetate to an aqueous solution of gum. These statements 
should be verified by experiment. Mucilago Acacia, U. S. P., is 
a solution of acacia in water and lime water. 

Tragacanth [Tragacantha, U. S. P.), is a mixture of soluble 
arabinoid gum and a variety of calcium gum, insoluble in water, 
termed bassorin. With water and glycerin a gelatinous mucilage 
is formed {Mucilago Tragacantha, U. S. P.). 

Calcium Carbide. 

Calcium carbide is of interest chiefly on account of the easy 
method of preparing acetylene which its interaction with 
water affords. It may be obtained by subjecting an intimate 
mixture of calcium oxide and carbon to the exceedingly high 
temperature of the electric furnace. The carbide has the 
composition CaCg, and is usually met with as a fused homo- 
geneous black mass, although when quite pure it is colorless 
and transparent. Water rapidly decomposes it, with the evo- 
lution of almost perfectly pure acetylene. Dilute acids behave 
in the same way as water ; concentrated nitric and sulphuric 
acids attack it but slightly. 

Analytical Reaction of Calciiim Salts. 

1. Add dilute suphuric acid to a solution of a calcium salt 
contained in a test-tube or small test-glass ; a precipitate of 
calcium sulphate, CaSO^, is formed if the solution is not too 
dilute. The calcium is not completely precipitated as sulphate, 
because this salt, unlike barium sulphate, is quite appreciably 
soluble in water. The addition of solution of calcium sulphate 
to a solution of another calcium salt does not produce a preci]>i- 
tate even on standing for some time or on boiling. (Compare 
the behavior of barium and of strontium salts). 



122 THE METALLIC RADICALS. 

Solution of Calcium Sulphate. — The official Calcium Sulphate 
Test Solution, U. S. P., is a saturated solution and contains one 
part of calcium sulphate in 378 parts of water. 

2. Add potassium chromate, K^CrO^, to a solution of a 
calcium salt slightly acidified with acetic acid; no precipitate 
is produced even on standing or on boiling. (Compare the 
behavior of barium and strontium salts.) 

These two reactions are most valuable in analysis, as every pre- 
cipitant of calcium is also a precipitant of barium and of strontium; 
but in dilute solutions, calcium sulphate and (in presence of acetic 
acid), potassium chromate are precipitants of barium only. 

Other Analytical Reactions. — To separate portions of a 
solution of a calcium salt, add ammonium carbonate, sodium 
phosphate and ammonium oxalate. Precipitates are obtained 
which correspond in appearance to those produced in the case 
of a solution of a barium salt; their composition is also 
analogous, hence their correct formulae can easily be deduced 
and equations written to represent the actions which take 
place. Of the precipitants just mentioned, ammonium oxalate 
is the one most commonly used as a reagent for calcium salts 
in the absence of barium. Calcium oxalate is insoluble in 
acetic, but soluble in hydrochloric or nitric acids. Calcium 
compounds impart a reddish color to the Bunsen flame. 



QUESTIONS AND EXERCISES. 



Write a paragraph on strontium, its natural compounds, chemical re- 
lations, technical applications and tests. — Enumerate some of the com- 
mon natural compounds of calcium. — Represent by an equation the ac- 
tion of hydrochloric acid on marble. — Why is calcium chloride used as a 
desiccating agent for gases?— How would you purify Calcium Chloride 
which has been made from ferruginous marble? — Give diagrams. — Write 
a few lines on chemistry of the lime-kiln.— What occurs when lime is 
"slaked"? — To what extent is lime soluble hi water (Liquor CaJcis, 
U. S. P. ) ; and in Syrup ( Syrupus Calcis, U. S. P. )?— Describe the preparation 
of the official Precipitated Calcium Carbonate {Calcii Carhonas Proecipi- 
tofits, U. S. P.); how does it differ from Prepared Chalk (Creta Prceparafa, 
U. S. P.)? — How does filter-paper differ from other kinds of paper? — Ex- 
plain the construction of a "wash-bottle."— Define r7cca»*frtffou.— State the 
difference l)etween bone-ash and Calcii Phosphas Proecipitatus.— How is 
" bone-earth " purified for use in medicine? — Give equations showing the 
conversion of Calcium Phosphate into Sodium Phosphate. — Write a short 
article on the manufacture composition, and uses of "bleaching-powder'' 
(Cnix Chiorinnta, U. S. P.).— How may calcium be detected in Gum 
Arahic?— State the chemical nature of 'Tragacanth.— To what extent is 
calcium sulphate .soluble in water?— Barium being absent, what reagents 
may be used for the detection of calcium?— Which is the chief test? 



MAGNESIUM. 123 

MAGNESIUM : Mg. Atomic Weight, 24.18. 

Occurrence, etc. — Magnesium is abundant in nature in the form 
of magnesian or mountain limestone, termed dolomite (after Dolo- 
mieu, a geologist), a double magnesium and calcium carbonate, 
in very common use as a building-stone, and magnesite, a toler- 
ably pure magnesium carbonate, though too ' ' stony ' ' for direct 
use in medicine, even if very finely powdered. Magnesium chlo- 
ride and magnesium sulphate (Epsom salt) occur in the water of 
many springs, and magnesium salts also occur in sea water and 
impart to it its bitter taste. A hydrous sulphate, MgSO^jHgO, 
termed kieserite, occurs near Stassfnrt, in Prussia. Metallic mag- 
nesium may be obtained from the chloride by strongly heating it 
with sodium. The metal burns readily in the air, emitting a daz- 
zling light due to the white heat to which the resulting particles 
of magnesia, MgO, are raised. The chloride to be employed as 
a source of the metal is obtained by dissolving the carbonate in 
hydrochloric acid, adding ammonium chloride, evaporating to dry- 
ness, heating the residue in a deep vessel (on the small scale, a 
large test-tube or flask), until the ammonium chloride is all volatil- 
ized, and the magnesium chloride remains as a clear fused liquid. 
The latter is poured upon a clean earthenware slab. The ammo- 
nium chloride is added in order to prevent the interaction of mag- 
nesium chloride and water which would otherwise take place in 
the last stages of the operation, with formation of magnesium 
oxide (or oxy chloride) and hydrochloric acid. 

Magnesium Sulphate. 

Experiment 1. — To a few drops of dilute sulphuric acid in a 
test-tube, add excess of powdered native magnesium car- 
bonate, magnesite, MgCOg, and boil until eflfervescence ceases 
and the carbonic anhydride has been completely expelled. 
The filtered liquid is a solution of magnesium sulphate, 
crystals of which, Epsom salt, MgSO^, 7H2O (Magnesii 
Sulphas, U. S. P.), may be obtained on boiling off most of 
the water, and setting the concentrated solution aside to cool. 
This is an ordinary manufacturing process. Instead of mag- 
nesite, dolomite may be employed, any iron being removed 
by evaporating the solution to dryness (after filtering from 
the calcium sulphate produced), gently igniting to decompose 
ferrous sulphate, dissolving in water, filtering from ferric 
oxide, and crystallizing. If neither mineral be at hand, the 
student may use a little of the ordinary magnesium carbonate 
used in pharmacy. 



MgCO, 


+ 


H,SO, = 


= ]\rgSO, + 


H,0 + CO,, 


lagncsite ' 




Sulphuric 


Mainiosium 


Water Carbouio 






acid 


sulphate 


anhydride 



124 THE METALLIC RADICALS. 

Magnesium sulphate crystallizes in large colorless, transparent, 
rhombic prisms; but, from concentrated solutions, the crystals are 
deposited in short, thin needles, a form more convenient for 
manipulation, solution, and general use in medicine. The crystal- 
lized salt loses 6H.,0 when heated to 300° F. (about 150°C.j. 

Iron may be detected in magnesium sulphate by adding a solu- 
tion of chlorinated lime or chlorinated soda to an aqueous solution 
of the salt ; brown ferric hydroxide, Fe(0H)3, is then precipitated. 
Ammonium hydrosulphide will also give a black precipitate if 
iron be present. 

Effervescent Magnesium Sulphate {Magnesii Sulphas Effervescens, 
U. S. P.), is magnesium sulphate dried on a water-bath until it 
no longer loses Aveight, and then mixed with citric and tartaric 
acids and sodium bicarbonate, and granulated. 

Magnesium Carbonates. 

Experiment 2. — To solution of magnesium sulphate add 
solution of sodium carbonate and boil; the resulting precipi- 
tate is magnesium carbonate (^Magnesii Carbonas, U. S. P.), 
a white, partly amorphous, partly minutely crystalline mag- 
nesium hydroxycarbonate, approximately 4MgC03, Mg(OH)^, 
dUfi. A denser, slightly granular precipitate of similar 
chemical composition is obtained by mixing concentrated 
solutions of the above salts, evaporating to dryness, then 
removing the sodium sulphate by digesting the residue in hot 
water, filtering, washing, and drying the precipitate. 

5MgSO,+5Na2C03+6H,0=4MgC03,Mg(OH)2,5H,04-5Na2S04+C02 

Magnesium Sodmm Water Official magnesium Sodium Carbonic 

sulphate carbonate carbonate sulphate anhydride 

The proportions for the preparation of the carbonate are 10 
parts of magnesium sulphate and 5 J of monohydrated sodium car- 
bonate, each dissolved in 80 of cold water, the solutions mixed, 
boiled for 15 minutes, the precipitate collected on a filter, well 
Avashed, drained, and dried at a temperature not exceeding 212°F. 
(100° C). The heavier carbonate is made with the same propor- 
tionates of salt, each dissolved in 20 parts instead of 80 of water, 
the mixture evaporated quite to dryness, and the residue digested 
in water and washed until all sodium sulphate is removed (until 
a Avhite precipitate of barium sulphate is no longer formed on the 
addition of solution of barium chloride or nitrate to a little of 
the filtrate). 

Another Process [Pattinson'' s). — Considerable quantities of mag- 
nesium carbonate are prepared by treating dolomite (p. 123) with 
carbonic anhydride under pressure. The magnesium carbonate 
dissolves before the calcium carbonate, and is then precipitated 



MAGNESIUM. 125 

from the clear solution by treatment with steam. (Compare next 
experiment.) 

Experiment 3. — Pass carbonic anhydride, generated as des- 
cribed on p. 76, into a mixture of water and magnesium car- 
bonate contained in a test-tube. After some time, separate 
any undissolved carbonate by filteration; the filtrate contains 
magnesium carbonate dissolved in carbonic acid. A solution 
containing about 10 grains of official carbonate in one ounce, 
is known as '^ Fluid Magnesia." 

The solution is made from freshly prepared carbonate. The 
latter is obtained by adding a hot solution of 2 ounces of mag- 
nesium sulphate in a half a pint of water to one of IJ ounces of 
monohydrated sodium carbonate in another half-pint of water, 
boiling the mixture for a short time (to complete decomposition), 
filtering, thoroughly washing the precipitate, placing the latter 
in 1 pint of distilled water, and transmitting carbonic anhydride 
through the liquid (say, at the rate of three or bubbles per second), 
for an hour or two, leaving the solution in contact with the gas 
under pressure of about three atmospheres for twenty-four hours, 
and, finally, decanting from undissolved carbonate; then, after 
passing in a little more gas, keeping in a well-closed bottle. 
Slight pressure is best produced by placing the carbonate and 
water in a bottle fitted with a cork and tubes as for a wash-bottle 
(p. 116), conveying the gas by the tube which reaches to the 
bottom, and allowing excess of gas to flow out by the upper tube, 
the outlet end of which is continued to the bottom of a small 
bottle in which mercury, to the depth of about an inch, has been 
placed. The bottle should be loosely plugged with cotton wool, 
to prevent loss of metal by spurting during the passage of the gas 
through it. (Each inch in depth of mercury through which the 
gas escapes corresponds to about half a pound pressure on every 
square inch of surface within the apparatus. ) 

Heat a portion of the solution: hydrous magnesium carbonate, 
MgC03, SHgO, is precipitated. A salt having the same composi- 
tion is deposited in crystals by the spontaneous evaporation of the 
solution. On exposure to cold, the solution sometimes afibrds 
large thick crystals (MgC03,5H20), which, in the air, lose water, 
become opaque, and then have the composition of those deposited 
by evaporation, (MgCO,, 3H,0). 

Magnesium Oxide. Magnesia. 

Experiment 4. — Heat magnesium carbonate in a porcelain 
crucible over a lamp (or in a larger earthen crucible in a fur- 
nace) till it ceases to effervesce on adding a dilute acid to a 



= 5MgO + 


6H,0 + 4CO2 


Magnesium 


AVater Carbonic 


oxide 


anhydride 



126 THE METALLIC RADICALS. 

small portion ; the residue is magnesia, MgO {Magnesii Oxi- 
dum, U. S. P.). The same operation on the heavy carbonate 
yields heavy magnesia, MgO {Magnesii Oxidum Ponderosum, 
U. S. P.)- Both are sometimes called calcined magnesia. A 
given weight of the official magnesia occupies three and one-half 
times the bulk of the same weight of heavy magnesia. 

4MgC03, Mg(0H)2, 5H2O 

Oflicial magnesium 
carbonate 

Magnesium oxide becomes hydroxide in water, slowly at 
60° F., rapidly at 212° F. A trace only of hydroxide is dis- 
solved. INIoisten some magnesia with water, and place the 
paste on red litmus-paper; the wet spot, after a time, becomes 
blue, showing that the hydroxide is slightly soluble. The 
oxide is liable to become hydroxy-carbonate on exposure to 
moist air. 

The official solution of Magnesium Citrate [Liquor Magnesii 
Citratis) is made by dissolving magnesium carbonate in solution 
of citric acid, adding the filtered solution to syrup of citric acid, 
contained in an aerated water-bottle, diluting, adding potassium 
bicarbonate, stoppering the bottle, and shaking occasionally until 
the potassium bicarbonate is dissolved. The formula magnesium 
citrate deposited from solution is Mg3(CgH50^).^, I4H2O. 

Analytical Reactions of Magnesium Salts. 

1. Add solution of ammonia or of ammonium carbonate to 
a solution of a magnesium salt (sulphate, for example), and 
warm the mixture in a test-tube; the precipitation of part 
only of the magnesium (as hydroxide, Mg(0H)2, or carbonate, 
MgCO^) occurs. Add now to a small portion of the mixture 
of precipitate and liquid a considerable excess of solution of 
ammonium chloride; the precipitate is dissolved. 

It is very necessary to note the solubility of magnesium hydroxide 
and carbonate in solution of ammonium chloride, as important 
analytical separations of magnesium from other metallic radicals 
depend upon it. In anahi;ical practice, the ammonium chloride 
should be added before the ammonia or the ammonium carbonate, 
as it is often easier to prevent precipitation than to redissolve a 
precipitate once formed. 

2. To some of the solution obtained in the preceding reac- 
tion, add solution of sodium or ammonium phosphate; a white 
granular precipitate of ammonium magnesium phosphate, 
NH^MgPO,, is produced. 



q UALITA TI VE A NAL YSIS. 



127 



3. To another portion of the same solution add ammonium 
arsenate; a white precipitate of ammonium magnesium arsen- 
ate, NH^MgAsO^, is produced, which is similar in appearance 
to the corresponding phosphate. 

Note. — Barium, strontium and calcium are also precipitated 
by alkali-metal phosphates and arsenates. The other precipitants 
of magnesium are also precipitants of barium, strontium and cal- 
cium. Hence the analyst always removes any barium, strontium, 
or calcium by an alkali-metal carbonate, as above indicated; 
sodium phosphate (or ammonium arsenate or phosphate) then 
becomes a very delicate test for the presence of magnesium. In 
speaking of magnesium tests, the absence of barium, strontium, 
and calcium salts is to be understood. 



DIRECTIONS FOR APPLYING THE FOREGOING ANALYTICAL REAC- 
TIONS TO THE ANALYSIS OF AN AQUEOUS SOLUTION OF A 
SALT OF ONE OF THE METALS, BARIUM, STRONTIUM, CAL- 
CIUM, MAGNESIUM. 

To a portion of the solution add ammonium chloride, ammonia 
water (until the liquid, after shaking, smells of ammonia), and 
ammonium carbonate. 



A white precipitate is produced. Acidulate an- 
other portion of the original solution with acetic acid, 
and add potassium chromate. ^ 



An immediate 
yellow precipi- 
tate indicates 

Ba 



No immediate precipitate is 
formed. To another portion of 
the original solution add calcium 
sulphate. 



A white pre- 
cipitate,formed 
on standing for 
some time, or 
on boiling, in- 
dicates 

Sr 



No precipitate 
even on stand- 
ing or on boil- 
ing, indicates 



Ca 



Confirm Ba, Sr, or Ca by flame-test. 



No precipitate 
is produced. To 
the same por- 
tion add ammo- 
nium phosphate. 
A white crystal- 
line precipitate 
produced either 
at once, or on 
standing for 
some time indi- 
cates 

Mg 



^Potassium bichromate must not be used in these operations, or 
a portion of the barium will remain in the liquid and be precipitated 
along with, or in the place of, the calcium carbonate, (see p. 110). The 
potassium chromate used must not contain carbonate, or calcium will 
be precipitated along with, or in the place of, barium. (The absence 
of carbonate may be proved by the non-occurrence of eflervesceuce on 
the addition of hydrochloric acid to a little of the solution of the chro- 
mate, previously made hot in a test-tube.) 



128 



THE METALLIC RADICALS, 



TABLE OF SHORT DIRECTIONS FOR APPLYING THE FOREGOING 
ANALYTICAL REACTIONS TO THE ANALYSIS OF AN AQUEOUS 
SOLUTION OF SALTS CONTAINING ANY OR ALL OF THE 
METALLIC RADICALS HITHERTO CONSIDERED. 

To a portion of the solution add ammonium chloride, ammonia 
water (until the liquid, after shaking, smells of ammonia), and 
ammonium carbonate. Warm and filter. 



Precipitate. 
BaCOg, SrCOg, CaCOg 
Dissolve on the filter in dilute nitric 
acid ; evaporate the solution to dryness ; 
digest the residue in a mixture of equal 
volumes of alcohol and ether : filter. 



Reaidue. 

Ba(X03),and SifXO;,),. 
Wash with mixture of 
alcohol and ether, dis- 
solve in water, add 
dilute acetic acid, and 
then KjCrO^ ; filter. 



Precipitate. 

Yellow, 
formed 
immedi- 
ately 
indicates 
Ba 



Filtrate. ! 
Add 

(XHJ,C03 
till alkaline. 
A white I 
precipitate j 
indicates 
Sr 



Filtrate. 

Contains 

Ca(XO,)., 
Expel the 
alcohol and 
ether by 
gently heat- 
ing on a 
water-bath. 
Dissolve the 
residue in 
water, and 
add 

(NH,),CA 

A white 

precipitate 

indicates 

Ca 



Confirm Ba, Sr, or Ca bv dissolving 
the BaCi-04, SrCOg, or CaCp, in HCl, 
and applying the flame-test. 



Filtrate. 

Add ammonium phosphate, 
allow to stand for some time, 
and filter. 



Precipitate. 

White crys- 
talling 

NH, MgP04 

indicates 
Mg 



Filtrate. 

( a ) Boil a por- 
tion. A white 
precipitate in- 
d i c ates Li. 
Confirm Li. 
bv flame-test 
ib) Test for K 
by the bis- 
muth thio-sul- 
phate test (p. 
83 and foot- 
note p. 106). 
(c) Test for 
Xa by flame- 
test. 

Test for XH, 
in the origi- 
nal solution 
by boiling 
with sodium 
hydro xide. 
Smell of am- 
monia indi- 
cates 



Note 1. — The analysis of solutions containing the foregoing 
metals is commenced by the addition of ammonium chloride and 
ammonia, simply as a precautionary measure, the former compound 
preventing partial precipitation of magnesium, the latter neutral- 
izing acids. The ammonium carbonate is the barium group pre- 
cipitant. 



DISTILL A TION. 1 29 

Note 2. — In the preceding, and in subsequent tables of analyti- 
cal processes, the leading precipitants will be found to be am- 
monium salts. These, being volatile, can be got rid of toward 
the end of the operations, and thus the detection of potassium and 
sodium is in no way prevented — an advantage which would be 
lost if such salts as potassium carbonate or sodium phosphate were 
the group precipitants employed. 

Note on Classification. — The compounds or barium, strontium, 
calcium and magnesium, have many analogies; their carbonates, 
phosphate and arsenates are insoluble in water, which sufficiently 
distinguishes them from the members of the group of alkali-metals. 
The solubility of their hydroxides in water marks their connection 
with the alkali-metals; the slightness of that solubility, diminish- 
ing as we advance farther and farther from the alkali-metals 
(baryta being most and magnesia least soluble in water) points to 
their connection with the next class of metals, the hydroxides of 
which are insoluble in water. These considerations must not, 
however, be over-valued. Though the solubility of their hydroxides 
places barium nearest and magnesium farthest from the alkali- 
metals, the solubility of their sulphates gives them the opposite 
order, magnesium sulphate being most soluble, calcium sulphate 
next, strontium sulphate third, while barium sulphate is practi- 
cally insoluble in water. The elements are sometimes described as 
the metals of the alkaline earth. 



QUESTIONS AND EXEECISES. 

Name the natural sources of the various magnesium salts.— Give a 
process for the preparation of Epsom salt.— Draw diagrams illustrative 
of the formation of magnesium sulphate from magnesite and from dolomite. 
—Is magnesia soluble in water?— How is "Fluid Magnesia" prepared?— 
Mention the effects of heat and cold on "Fluid Magnesia".— Ascertain 
how much magnesia (MgO) can be obtained from 100 grains of Epsom 
salt.— Calculate the amount of official Magnesium Carbonate which will 
yield 100 grains of magnesia.— Can magnesium be detected in presence 
of barium, strontium, or calcium?— Describe the analj^sis of an aqueous 
liquid containing salts of barium, strontium, calcium and magnesium. — 
How may magnesium be precipitated from solutions containing ammonium 
salts ? 



Distillation. 

The water with which, in analysis, solution of a salt or dilution 
of a liquid is effected should be pure. Well- and river-waters are 
unfit for the purpose, because they contain dissolved salts to the 
extent of some 20 to 60 grains or more per gallon, derived from the 

9 



130 THE METALLIC RADICALS. 

soil through which the water percolates ; and rain-water is not in- 
frequently contaminated with the dust and debris which fall on the 
roofs whence it is usually collected. Such water is purified by 
distillation, an operation in which the water is, by boiling, con- 
verted into steam and the steam condensed again to water in a 
separate vessel, the fixed salts remaining in the vessel in which 
the water is boiled. On the large scale, the boiling is carried on 
in metal boilers fitted with a hood or head in which there is a 
wide lateral channel through which the steam passes; on the small 
scale, either a common glass flask is employed, into the neck of 
which a glass tube, bent to an acute angle, is fitted by means of a 
cork; or a retort is used {a, Fig. 29), a species of long-necked 

Fig. 29. 



Distillation, on small scale. 

flask, bent near the body, by the glass-worker, to an appropriate 
angle (hence the name retort, from retorgueo, I bend back). Con- 
densation is effected by surrounding the outlet tube through which 
the steam passes, with cold water. In large stills the steam-tube, 
or condensing-ivorm, is usually a metal (tin) pipe, coiled into a 
spiral form for the sake of compactness, and so fixed in a tube 
that a few inches of one end of the pipe may pass through and 
closely fit a hole bored near the bottom of the tub. Cold water 
is kept in contact with the exterior of the pipe, provision being 
made for a continuous supply to the bottom, while the lighter 
water, heated by the condensing steam, runs off" from the top of 
the tub. The condenser fitted to a flask or retort may be a simjjle 
glass tube of any size, placed within a much wider tube (a com- 
mon long, narrow lamp-glass may ansAver for experimental opera- 
ations), the inner tube being fitted to the wider one by means of 
bored corks ; a stream of water passes in at one end of the enclosed 
space (the end fiirthest from the retort), through a small glass tube 
inserted in the cork, and out at the other end through a similar 
tube. The common (Liebig's) form of laboratory condenser is a 
glass tube from one-half to three-fourths of an inch wide and a 



ZINC. 131 

yard long (6, Fig. 29), surrounded by an outer tube (c, Fig. 29) 
somewliat shorter and about two inches in diameter, having at 
each extremity a neck, through which the inner glass tube passes. 
The junctions of the outer tube with the inner tube are made by 
means of short, wide India-rubber tubes {d and e, Fig. 29). An 
inlet (/, Fig. 29) near the lower part of the outer tube provides 
for the admission of a current of cold water, conveyed by India- 
rubber tubing, while an outlet near the top [g, Fig. 29) allows the 
escape of heated water into the sink. The inner tube may thus 
be kept constantly surrounded by cold water, and heated vapors 
passing through it may be perfectly cooled and condensed, and 
collected in a receiver (A, Fig. 29). 

In distilling several gallons of water for analytical or medicinal 
purposes {Aqua Distillata, U. S. P.), the first two or three pints 
should be rejected, because they are likely to contain traces of 
ammonia and other volatile impurities. 

Pure water is not found in nature ; natural water always con- 
tains some solid matter in solution, and also dissolved gases. The 
amount and kind of matter held in solution vary with the source 
of the water. Water used for distillation should not contain any 
large amount of impurities, but should be such as is usually sup- 
plied to large towns. 

Rectification is the process of redistilling a distilled liquid. 
Rectified spirit is a spirit of wine which has been thus treated. 

Dry or destructive distillation is distillation in which the con- 
densed products are directly formed by the decomposing influence 
of the heat applied to the dry or non-volatile substances in the re- 
tort or still, as in the distillation of coal in the manufacture of 
coal gas. 

Exercise. — Write from memory a short description of distillation. 



At this stage the student is again recommended to read the para- 
graphs on the general principles of chemical philosophij {pages 49 to 
69), and to return to them from time to time, U7itil they are thoroughly 
comprehended. 

ZINC : Zn. Atomic weight, 64.9. 

Occurrence, etc. — Zinc is tolerably abundant in nature as sul- 
phide, ZnS, blende, and carbonate, ZnCO.^, calamine (from cala- 
mus, a reed, in allusion to the appearance of the mineral). The 
ores are roasted to expel suli)hur, carbonic anhydride, and some 
impurities, and the resulting oxide is heated with charcoal, when 
the metal vaporizes and condenses on cooling. Zinc is a britth" 
metal, but at a temperature somewhat below 800°F. (148.8°0. \ 
it is malleable, and mav be rolled into thin sheets. Above 400° 



132 THE METALLIC RADICALS. 

(204. 4°C.), it is again brittle, and may then be pulverized. It 
melts at 773°F. (411. 7°C.), and is volatile at a bright red heat. 
Zinc in exceptionally fine powder ignites spontaneously, especially 
if damp, or if stored in a warm place. 

Uses. — The uses of zinc as a metal are important; alloyed with 
copper and nickel it yields German silver; with twice its weight 
of copper it forms brass, and as a coating on iron (the so-called 
galvanized iron) greatly retards the formation of rust. Most of 
the salts of zinc are prepared, directly or indirectly, from metallic 
zinc {Zincu7n, U. S. P.). 

Jlolecidar Formula. — Some remarks on this point will be made 
under Mercury. 

Zinc Sulphate. 

Experiment 1. — Heat zinc (4 parts) with water (20 parts) 
and sulphuric acid (3 fluid parts) in a test-tube (or larger 
vessel) until no more hydrogen is evolved; solution of zinc 
sulphate results. Filter (to separate the particles of lead, 
carbon, etc., present in ordinary zinc), and concentrate the 
solution in an evaporating-dish; on cooling, colorless prismatic 
crystals of Zinc Sulphate, Zn^O ^JUfi (Zinci SulpJias, 
U. S. P. ) are deposited. 

Zn + H^SO, = ZnSO, + H^ 

Zinc Sulphuric acid Zinc sulphate Hydrogen 

The sulphuric acid used in this experiment must be diluted 
with a considerable quantity of water, as above. Cold con- 
centrated sulphuric acid does not attack zinc. 

JVofe. — Of several methods of preparing hydrogen, the one just 
described is the most convenient ; of the two or three means of 
preparing zinc sulphate, it is that most commonly employed; and 
of the many reactions which may be utilized for obtaining a cur- 
rent of electricity, it is one of the most convenient. The apparatus 
in which the reaction is affected differs according to the require- 
ments of the operator: if the zinc sulphate alone is wanted, an 
open dish is all that is necessary, the action being accelerated if 
necessary by heat; if hydrogen is required, a closed vessel and de- 
livery-tube may be used; if a current of electricity is desired, the 
zinc and sulphuric acid, along with other materials, are placed in 
glass or earthenware cells, the whole being arranged so as to form 
a battery. 

Purificafion. — Impure zinc sulphate may be purified in the 
same manner as impure chloride {see next experiment). 



ZINC. 133 

Zinc sulphate is isomorphous ^ with magnesium sulphate, and, 
like that salt, loses 6H,0 when heated to 300°F. (about 150°C.). 
An old name for it is white vitriol. 

Zinc Chloride. 

Experiment 2. — Digest zinc iu hydrochloric acid mixed 
with half its bulk of water ; the resulting solution contains 
zinc chloride. Evaporate the liquid until no more steam 
escapes; Zinc Chloride, ZnCl^, in a state of fusion remains, 
and, on cooling, is obtained as an opaque white solid (Zinci 
CJdoridum, U. S. P.). It is soluble in water and in alcohol. 

Zn + 2HC1 = ZnCl^ + H, 

Zinc Hydrochloric acid Zinc chloride Hydrogen 

This reaction is analogous to that described in the preceding 
experiment. Burnett' s deodorizing or disinfecting liquid is a solu- 
tion of zinc chloride. 

Purification of Zinc Chloride or Sulphate. — Zinc sometimes con- 
tains traces of iron or lead; and these, like zinc, are dissolved by 
most acids, with formation of soluble salts: they may be recognized 
in the solutions by applying the test described on p. 137. Should 
either be present, a little chlorine water is added to the solution 
till the odor of chlorine is permanent, and then the whole is well 
shaken with some zinc hydroxide or the official zinc carbonate. 
In this way the iron is precipitated as ferric hydroxide, and the 
lead as peroxide: — 

2FeCl,2 + CI, = 2FeCl32 
Ferrous chloride Chlorine Ferric chloride 

2FeCl3 + 3Zn(OH)2 = 2Fe(OH)3 + 3ZnCl2 

Ferric Zinc Ferric Zinc 

chloride hydroxide hydroxide chloride 

PbCl, -h CI, + 2Zn(0H), - PbO, + 2ZnCl, + 2H,0 
Toad Chlorine Zinc Lead Zinc Water 

eliloride hydroxide peroxide chloride 

If zinc sulphate is being purified by the above method the 
action of chlorine on any ferrous sulphate present will result in 
the formation of ferric sulphate: — 

6FeS0, + 3C1, = 2Fe,(S0,),, + 2FeCl3; 

^ Isomorphous bodies (lo-o?, isos, equal, and iJiop(j)r], moyphe. form) are those 
which are similar in the shape of their crystals. This identity in crys- 
talline form is frequently met with among- substances of analotiinis 
composition, such as zinc sulphate, ZnS0t,7HL>0, and magnesium sulphate, 
MgS04,7H2(). 

2 It will be noticed that the atom of iron is represented, in. this equa- 
tion, as both bivalent and trivalent; this will be alluded to when iron 
comes under consideration. 



'H > 



134 THE METALLIC RADICALS. 

zinc carbonate will then give zinc chloride as well as sulphate, 
and thus the whole quantity of zinc sulphate will be slightly con- 
taminated by chloride. On evaporating and crystallizing, how- 
ever, the zinc chloride will be retained in the mother-liquor. 
These processes of purification admit of general application.^ 

In the Pharmacopeia, the possible presence of impurities in the 
zinc is recognized, and the process of purification just described 
is incorporated with the process of preparation of Liquor Zinci 
Chloridi, U. S. P., nitric acid being used mstead of chlorine 
water to convert ferrous salt into ferric. 

Zinc Bromide, ZnBr,, and Zinc Iodide, Znl^, are also official. 

Zinc Carbonate. 

Experiment 3. — To the solution of any given quantity of 
zinc sulphate in twice its weight of water, add about an equal 
quantity of sodium carbonate, also dissolved in twice its 
weight of water, and boil ; the resulting white precipitate is 
Hydrated Zinc Carbonate {Zinci Carhonas Proecijnatus, 
U. S. P.). As a hydroxy-carbonate, it is capable of being 
represented as made up of zinc carbonate, ZnCo3 and zinc 
hydroxide, Zn(0H)2, approximately in the proportion of one 
molecule of the former and two of the latter, together with a 
molecule of water (ZNCO^, 2Zn(0H).„ H,0); Ihese propor- 
tions, however, vary considerably. It may be washed, 
drained, and dried in the usual manner. It is used in the 
arts under the name of zinc-white. 

3ZnS0, + 3H,0 + SXa.CO, 
Zinc sulphate "Water Sodium carbonate 

= ZnC03,2Zn(OH),,H20 + 2C0/ + 3Xa,S0, 

Zinc hydroxycarbonate Carbonic Sodium 

anhydride sulphate 

Calamina Pr(pparcda is a smooth, pale, pinkish-brown powder, 
obtained by calcining and powdering native zinc carbonate or cal- 
amine, and freeing the product from gritty particles by elutriation. 
Prepared calamine is chiefly zinc carbonate with some oxide of 
iron, etc. 

Elutriaiion (Lat. ehdriafu.s, fi'om elutrio, I decant; elno, I wash 
out). This fractional operation consists of decantino; off" water or 
other liquid containing lighter and finer particles in suspension, 
from heavier and coarser particles which have become deposited. 
The decanted fluid yields a sediment of the fine particles on 
standing. By allowing varying intervals of time to elapse 
between the shaking and the decantation, and by using fluids of 
different specific gravities and different degrees of limpidity or 



ZINC. 135 

viscidity, substances of different specific gravities, or particles of 
different degrees of fineness of any one substance, may be sepa- 
rated from each other. 

Zinc Acetate. 

Experiment 4. — Collect on a filter the precipitate obtained 

in the last experiment, wash with distilled water, and dissolve 

a portion in concentrated acetic acid; the resulting solution 

contains zinc acetate, and, on evaporating and setting aside, 

yields lamellar pearly crystals of zinc acetate, Z\i{C,^]lfij.^, 

2Hp {Zinci Acetas, U. S. P.). 

ZnC03,2Zn(OH)2,H-20 + 6HC2H802 = 3Zu(C2H302)2 + 6H2O + CO2 
Zinc hydroxycarbonate Acetic acid Zinc acetate Water Carbonic 

anhydride 

Zinc Oxide. 

Experiment 5. — Dry on a water-bath the remainder of the 
precipitated zinc carbonate obtained in experiment 3, and then 
heat it in a small crucible until a sample taken out of the 
crucible does not effervesce on the addition of a dilute acid; the 
product is Zinc Oxide (Zinci Oxidum, U. S. P.), much used 
in the form of Ointment ( Unguentum Zinci Oxidi, U. S. P.). 



:nC03,2Zn(OH),,H20 


--= 3ZnO 


-f 


3H,0 


+ CO, 


Zinc liydroxycarbonate 


Zinc oxide 




Water 


Carbonic 
anliydride 



Note. — Zinc oxide prepared as above is yellow while hot, and 
of a very pale yellow or slight buff tint when cold, not actually 
white like the oxide prepared by the combustion of zinc in air. 
The preparation of the latter variety, which also occurs in com- 




The blowpipe. 

merce, can only be practically acconiplislied on the large scale: 
but the chief features of the action may be observed by heating a 
piece of zinc on charcoal in the blowpipe-fiaine {a, Fig. 80) till it 



136 THE METALLIC RADICALS. 

burns; flocks escape, float about in the air, and slowly fall. These 
were formerly called Flores Zlnci, Lana Philosophica, or Nihiluni 
Album. Zinc oxide slowly absorbs carbonic anhydride and water 
from moist air, and becomes converted into hydroxy carbonate. 

A clear blowpipe-flame consists of two more or less sharply 
defined portions (6, Fig. 30), an inner cone, at the apex of w^hich 
there are hot hydrocarbon gases ready to combine wdth oxygen, 
and an outer cone, at the apex of which there is excess of hot 
oxygen. At the latter point oxidizable metals, etc., are readily 
oxidized, as in the foregoing experiment, and that part of the 
flame is therefore termed the oxodizing flame ; in the inner flame, 
oxides and other compounds are reduced to the metallic state, 
hence that part is termed the reducing flame (a grain of lead 
acetate may be employed for illustration). A blowpipe-flame is 
much altered in character by slight variations in the position of 
the nozzle of the blowpipe, by the form of the nozzle, by the 
force with which air is expelled from the blowpipe, and by the 
character of the jet of gas. 

Zinc Valerandate. 

Experiment 6. — Zinc Valerandate, or rather, zinc iso-valer- 
andate, ZwiQ.l^^O^^ 2H,0 (Ziiici Valerandas, U. S. P. ), is 
prepared by saturating iso-valerandic acid with zinc carbon- 
ate or by mixing concentrated solutions of zinc sulphate and 
sodium iso- valerandate, cooling, separating the w^hite pearly 
crystalline precipitate, evaporating the solution at 200° F. 
(93.3° C), to a small volume, cooling, again separating the 
lamellar crytals, washing the whole product with a small 
quantity of cold distilled water, draining, and drying by ex- 
posure to air at ordinary temperatures. Zinc iso- valerandate 
is soluble in ether, alcohol, and hot water. See also valer- 
andic acid. 

ZnSO, + 2NaC,H,0, = Na.SO, + Zn(qH,0,), 

Zinc sulphate Sodium iso-valerandate Sodium sulphate Zinc iso-valerandate 

Zinc Sulphide and Zhic Hydroxide are mentioned in sub- 
sequent paragraphs. The formula of Ziiic Sulphite is ZnSO„, 
3H.p. 

Zinc Phenolsulphonate, Zn(C^B.fi^8X,SB.fi{ZineiPhenol- 
sulphonas), and Zinc Stearate, (Zinci Stearas), are included 
in the Pharmacopoeia. 

AnalyUcal Reactions of Zinc Salts. 

1. To a solution of a zinc salt (sulphate, for example), in 
a test-tube, add solution of ammonium hydrosulphide, 



ZINC. 137 

NH^SH ; a white precipitate of zinc sulphide, ZnS, is pro- 
duced which is insoluble in acetic, but soluble in dilute 
hydrochloric or sulphuric acid. 

2^ote. — This is the only white sulphide that will be met with. 
If the zinc salt contains iron or lead as impurities, the precipitate 
will have a dark appearance, due to admixture with the sulphides 
of these metals, which are black. Aluminium hydroxide, which 
is white and may also be precipitated on the addition of ammon- 
ium hydrosulphide, is the only substance for which zinc sulphide, 
is likely to be mistaken, or which is likely to be mistaken for 
zinc sulphide. As will be seen immediately, there are good 
means of distinguishing these substances from each other. 

2. To a solution of a zinc salt add ammonia water ; a 
white precipitate of zinc hydroxide, Zn(0H)2, is formed. 
Add excess of the reagent; the precipitate is redissolved. 
This reaction at once distinguishes a zinc salt from an alumi- 
nium salt, unless the solution of the latter is very dilute, 
aluminium hydroxide being almost insoluble in dilute am- 
monia. 

Other Analytical Reactions. — Potassium or sodium hy- 
droxide affords a reaction similar to that just mentioned, the 
zinc hydroxide redissolving if the alkali does not contain too 
much carbonate. The solution contains potassium or sodium 
zincate : — 



Zn(OH), 


+ 


2K0H = 


- K,ZnO, 


+ 


2H,0 


Zinc 




Caustic 


Potassium 




Water 


hydroxide 




potash 


zincate 







(Metallic zinc dissolves in solution of potassium or sodium 
hydroxide giving hydrogen and potassium or sodium zincate : 
— Zn+2KOH=K2Zn02-|-H2.) Ammonium carbonate yields 
a white precipitate of basic zinc carbonate, soluble in excess. 
Potassium and sodium carbonates gives a similar precipitate, 
which is not redissolved if the mixed solution and precipitate 
be well boiled to expel carbonic anhydride. Potassium 
ferrocyanide produces a white precipitate of zinc ferrocyanide, 
Zn,Fe(Cn),. 

Magnesium sulphate, which is isomorphous with and indis- 
tinguishable in appearance from zinc sulphate, does not yielil 
and precipitate when either potassium ferrocyanide or ammonium 
hydrosulphide is added to its aqueous solution. 

Antidotes.— T\\QYQ are no efficient chemical means of counteract- 
ing the poisonous effects of zinc. Large doses, fortunately, act as 



138 THE METALLIC RADICALS. 

powerful emetics. If vomiting has not occurred, or apparently to 
an insufficient extent, solution of sodium carbonate (common 
washing soda), immediately followed by white of egg and demul- 
cents, may be administered, and the stomach then be cleared. 



QUESTIONS AND EXEECISES. 

Give the sources and uses of metallic zinc. — Give a diagram repre- 
senting the action of zinc on dilute sulphuric acid. — How may solutions 
of Zinc Chloride or Sulphate be purified from iron salts ? Give equations 
for the reactions. — Give the formula of the official Zinc Carbonate, and 
illustrate by a diagram the reaction which takes place in its production. 
— Give an equation representing the preparation of Zinc Acetate. — In 
what respect does Zinc Oxide, resulting from the ignition of the carbon- 
ate, differ from that produced during the combustion of the metal ? — 
How is Zinc Iso-valerandate prepared and what are its properties? — 
Name the more important tests for zinc. — How would you distinguish, 
chemically, between solutions of Zinc Sulphate and of Alum? — Give 
reactions distinguishing Zinc Sulphate from Magneium Sulphate. — 
Describe the treatment in cases of poisoning by zinc salts. 



MANGANESE : Mn. Atomic weight, 54.6. 

Source. — Manganese is a constituent of many minerals, and is 
met with in abundance in the south-west of England, in Aber- 
deenshire, and in most countries of Europe, as black oxide, MnO^, 
pyrolusite (from Tzvp, pui\ tire, and /.vaic, lusis, a loosing or resohdng, 
in allusion to the readiness with which it is split up by heat into 
a lower oxide and oxygen). This mineral occurs as a steel-grey 
mass of prismatic crj^stals, or in black amorphous lumps. 

Uses. — Metallic manganese, which may be isolated, among 
other methods, by the action of sodium on manganese fluoride, is 
used in alloy with iron in the manufacture of some varieties of 
steel. The black oxide is an important agent in the production 
of chlorine, and in the preparation of manganates and permangan- 
ates, purple glass, and black glaze for earthenware. Mangani 
Dio.ridum Prcecipitatum, Mangani Hypophosphis aud Mangani 
Sulphas are included in the Pharmacopoeia. 

Experiments having both Synthetical and 
Analytical Interest. 

Experiment 1. — Boil some black manganese oxide with 
concentrated hydrochloric acid in a test-tube or flask, placed 
in a fume-cupboard, until chlorine is no longer evolved; filter; 
the filtrate is a solution of manganous choride, MuCL.MnO.-}- 
4HCl=MnCl,+2HO+Cl,. 



MANGANESE. 139 

This is the reaction commonly employed in the preparation of 
chlorine. It is also a ready method of preparing a manganous salt 
for analytical experiments. Coupled with the application of 
reagents to the filtrate, the reaction is one of those by which a 
black powder or mineral would be recognized as black manganese 
oxide. Black manganese oxide also dissolves in cold concentrated 
hydrochloric acid, forming a dark-brown solution which contains 
a chloride, MnClg, mixed, probably, with other manganese chlo- 
rides. 

Experiment 2. — Heat a manganese compound with a grain 
or two of potassium hydroxide or carbonate and a fragment of 
potassium nitrate or chlorate on platinum foil in the blowpipe- 
flame ; a green mass containing potassium manganate, K^MnO^, 
is formed. Boil the foil and the fused mass in water ; the 
manganate dissolves yielding a green solution w^hich soon 
changes to purple owing to the formation of potassium per- 
manganate, KMnO^. Carefully performed, this is a delicate 
test for manganese. 

This reaction is the one by which potassium permanganate 
(Potassium Per7nanganas,V. S. P.), is prepared. Equations show- 
ing the action which occurs in making the salt have already been 
given in connection with the compounds of potassium (see p. 81). 

Instead of converting the manganate by ebullition (as described 
on p. 81), and neutralizing the free alkali by acid, whereby one- 
third of the manganese is precipitated, chlorine may be passed 
through the cold solution until the green color is entirely changed 
to purple. 2K2MnO,+ 01^= 2KMnO,+ 2KC1. 

Solutions of potassium and sodium manganates and permanganates 
are in common use as green and purple disinfecting fluids. They 
act by oxidizing organic matter, the manganic or permanganic 
radical being reduced and a dark-brown manganite formed. For 
this reason asbestos should be used instead of paper in filtering 
the solutions. 

The changes in color which the green manganate undergoes 
when dropped into warm water gave rise to the old name 7niner(d 
chameleon, by which the manganate is still sometimes described. 

Experiment 3. — Make a borax bead by heating a fragment 
of borax on the end of a platinum wire in the blowpipe- 
flame until a clear transparent globule is obtained. Place a 
minute particle of a manganese compound, or a drop of a 
solution of a manganese salt, upon the bead and heat it again 
in the oxidizing flame. A bead of a pale violet or amethyst 
tint is produced. (This is useful as an analytical reaction, 
and it illustrates the use of black manganese oxide in pro- 



140 THE METALLIC RADICALS. 

ducing common purple-tinted glass). Expose the bead to 
the reducing part of the flame (p. 136), the color disappears. 
The change is owing to the reduction of the manganic com- 
pound to a manganous compound which is nearly colorless 
(compare ferrous and ferric compounds, p. 151). This action 
also illustrates the use of black manganese oxide in glass- 
manufacture. Glass, when first made, is usually of a green 
tint, owing to the presence of small quantities of ferrous com- 
pounds; the addition of the manganese oxide to the materials 
converts the ferrous into ferric compounds, which have com- 
paratively little color, it itself being thereby reduced to mangan- 
ous oxide which also gives but little color. If excess of the 
manganese oxide is added, a purple tint is produced. 

Manganese borate is an article of commerce used for the pre- 
paration of drying oil and oil varnishes. When moist, it acts as 
an oxidizing agent with great facility, especially on warming. 

Experiment 4. — Through a solution of a manganous salt, 
acidulated with hydrochloric acid, pass hydrogen sulphide ; 
no precipitate is produced. Add ammonia ; the ammonium 
hydrosulphide thus formed produces a yellowish-pink or flesh- 
tint precipitate of manganous sulphide, MnS. 

This reaction is characteristic, manganese sulphide being the 
only flesh-colored sulphide known. The salt used may be the 
manganous chloride prepared in experiment 1; but such crude 
solutions usually give a black precipitate with ammonium hydro- 
sulphide, owing to the presence of iron. Pure manganous chloride 
may be obtained by boiling the impure solution with manganous 
carbonate; the latter decomposes the ferric chloride, w^ith the 
production of ferric hydroxide and more manganous chloride, and 
the evolution of carbonic anhydride. 

To the recently precipitated manganous sulphide add. acetic 
acid; it dissolves. This solubility permits of the separation of 
manganese from nickel, cobalt and zinc, the sulphides of w^hich 
are insoluble in dilute acetic acid. To express the fact in another 
way, manganese is not precipitated by hydrogen sulphide from a 
solution containing free acetic acid. 

Experiment 5. — To a solution of a manganous salt add 
ammonia water ; a white precipitate of manganous hydroxide, 
MnfOH)^ is produced. Add excess of ammonia water ; some 
of the precipitate is dissolved, and may be detected in the 
quickly filtered solution by the addition of ammonium hydro- 



COBALT. 141 

sulphide. But both precipitate and solution rapidly absorb 
oxygen, the manganese passing into a more highly oxidized 
condition, in which it is insoluble in ammonia. Potassium 
and sodium hydroxides give a similar precipitate insoluble in 
excess. The precipitate rapidly absorbs oxygen, becoming 
brown, and gradually passing into a higher state of oxidation. 
Experiment 6. — To a solution of a manganous salt add 
dilute nitric acid, and either red lead or lead peroxide, and then 
boil; a red tint is imparted to the liquid, due to the formation 
of permanganic acid. If chlorides are present, the mangan- 
ese, etc., should be separated by means of sodium hydroxide 
solution, the precipitate well washed, dissolved in nitric 
acid, and the oxide then added. (Crum). Or the chlorides 
may be got rid of by heating with sulphuric acid until all 
hydrochloric acid has been expelled (Alcock), and then ap- 
plying Crum's test. An improvement on Crum's test consists 
in warming the solution to be tested, which should be free 
from chloride, with a small quantity of ammonium persul- 
phate to which a drop of a dilute solution of silver nitrate 
has been added. (H. Marshall). The purple color of the 
solution of permanganic acid is much more easily observed 
when this method is employed. 

COBALT : Co. Atomic Weight, 58.56. '!; 

Sources. — Cobalt occurs sparingly in nature as the arsenide, % 

CoASg, tin-white cobalt, and occasionally as a double arsenide I 

and sulphide, CoAsS, or cobalt-glance (from glanz, brightness, in 
allusion to its lustre). 

Uses. — Its chief use is in the manufacture of blue glass. A 
cobalt compound is also the coloring constitutent of smalt, (from 
smell, a corruption of melt), a variety of blue glass reduced to a j 

fine powder and used as pigment by paper-stainers and others, ^ I 

and employed by laundresses to conceal the yellow tint of imper- 
fectly washed linen. 

Cobalt salts, which are mostly reddish and yield pink or red 
solutions, may be obtained from the oxide, CoO; and the oxide 
from zaffre, a mixture of sand and roasted ore which is chiefly 
cobalt arsenate. Metallic cobalt is obtained by reducing cobalt 
oxide (by heating in a current of hydrogen), or by heating cobalt 
oxalate in the absence of air. 



142 



THE METALLIC RADICALS. 



Analytical Reactions of Cobalt Salts. 

1. Pass hydrogen sulphide through an acidulated solution 
of a cobalt salt (cobalt chloride, CoClg, or nitrate, 00(^03)2, 
for example); no precipitate is produced. Add ammonia 
water; the ammonium hydrosulphide thus formed causes pre- 
cipitation of black cobalt sulphide, CoS. (The moist precipi- 
tate slowly absorbs oxygen from the air, yielding some cobalt 
sulphate, CoSOJ. 

2. Gradually add ammonia water to a solution of a cobalt 
salt ; a blue precipitate of basic salt is produced. Add excess 
of ammonia; the precipitate is dissolved, yielding a nearly 
colorless solution, which is rapidly oxidized by the oxygen of 
the air and becomes brown thereby. Potassium and sodium 
hydroxides also produce a precipitate of basic salt insoluble 
in excess. 

3. Make a borax bead by heating a fragment of borax on 
the end of a platinum wire in the blowpipe-flame until a clear 
transparent globule is obtained. Place a minute particle of 
any cobalt compound, or a drop of a solution of a cobalt salt, 
upon the bead and heat it again; a blue bead results, in both 
oxidizing and reducing flames. This is a delicate test for 
cobalt. 

4. To a solution of a salt of cobalt add solution of potassium 
cyanide until the precipitate which at first forms has entirely 
redissolved, and further add considerable excess of the cyanide. 
Then add solution of potassium hydroxide in considerable 
quantity and an oxidizing agent such as bromine water, and 
warm. Potassium cobalticyanide, KgCoCgNg, is formed in sol u- 
tion but no precipitate is produced. When a nickel solution 
is similarly treated, the nickel is completely precipitated as 
black nickelic hydroxide ; hence this action aff^ords a means 
of separating these closely allied metals from each other. 

5. To a solution of a cobalt salt add excess of a freshly pre- 
pared solution of potassium nitrite in dilute acetic acid. The 
cobalt is completely precipitated as yellow potassium cobaltic 
nitrite (Fischer's Salt), K,Co(N02)g. Nickel salts do not 
give any corresponding reaction. 

Invisible Ink. — Many cobalt compounds containing water 
of crystallization are light red, and in the anhydrous state 
are more or less blue. Prove this by writing some words on 
paper with a solution of cobalt chloride sufficiently dilute for 
the characters to be invisible when dry : hold the sheet before 



NICKEL. 143 

a fire or over a flame ; the letters at once become distinctly 
visible, and of a blue color. Breathe on the words, or set 
the sheet aside for some time, the characters become once 
more invisible, owing to the absorption of moisture. Hence 
solution of cobalt chloride forms one of the so-called sympa- 
thetic inks. 

NICKEL : Ni. Atomic weight, 58.3. 

Sources. — The ores of nickel and cobalt are commonly associated 
in nature. Indeed it is from speiss, a nickel arsenio-sulphide ob- 
tained in the manufacture of smalt, a pigment of cobalt which 
has already been mentioned, that much of the nickel of com- 
merce has hitherto been obtained. Garnierite, magnesium and 
nickel silicate, containing no cabalt, is also a valuable source of 
nickel. 

Uses. — Nickel is used in the preparation of the white alloy 
known as Grerman or nickel silver, and is extensively employed 
for plating iron. 

Nickel salts, which are generally green and yield a green solu- 
tions, are chiefly made, directly or indirectly, from the metal itself 
The latter is obtained by reduction of the oxide by strongly heating 
it with charcoal. 

Analytical Reaction of Nickel Salts. 

1. Pass hydrogen sulphide through an acidulated solution 
of a nickel salt (nickel chloride, NiCl2, nitrate, ^1(^03)2, or 
sulphate NiSO^); no precipitate is produced. Add ammo- 
nia water ; the ammonium hydrosulphide thus formed causes 
precipitation of black nickel sulphide, NiS. 

Note. — When nickel sulphide is precipitated by the addition of 
ordinary ammonium hydrosulphide, which contains free sulphur, 
difficulty is experienced in obtaining a clear liquid on filtering 
the mixture, owing to the fact that nickel sulphide dissolves to 
some extent in excess of yellow ammonium hydrosulphide, form- 
ing a dark-colored liquid from which nickel sulphide separates 
slowly on exposure to the air. From this filtrate, the whole of 
the nickel can be separated in the form of sulphide by adding 
excess of acetic acid (which decomposes the yellow ammoniuiu 
hydrosulphide — the solvent of the nickel sulphide) and filtering 
again. It can also be separated by driving away the annnoniuni 
hydrosulphide by evaporation, and refiltering. In the latter 
method, some of the nickel sulphide usually undergoes oxidatii)u 
into nickel sulphate, NiSO^, which passes into solution and nuist 



144 THE METALLIC RADICALS. 

be removed by reprecipitation as sulphide (by adding a few drops 
of solution of ammonium hydrosulphide and then acidulating 
with acetic acid), and filtration. It is occasionally practicable 
to avoid the difficulty by precipitating the nickel sulphide from 
an ammoniacal solution by means of hydrogen sulphide, or by 
using freshly-made ammonium hydrosulphide in which nickel 
sulphide is insoluble. 

2. Add ammonia water drop by drop to a solution of a 
nickel salt ; a pale-green precipitate of basic salt is produced, 
especially on boiling the mixture. Add excess of ammonia ; 
the precipitate dissolves, yielding a blue solution. Potassium 
and sodium hydroxides produce a pale-green precipitate of 
of nickel hydroxide, Ni(0H)2, insoluble in excess. 

3. Mckel salts color a borax bead reddish-yellow when 
heated in the oxidizing flame ; on heating in the reducing 
flame, the bead becomes gray and opaque. 

4. To a solution of a nickel salt add solution of potassium 
cyanide ; nickel cyanide, Ni(CN)2, is precipitated. Add excess 
of solution of potassium cyanide ; the precipitate is dissolved 
with formation of potassium nickel cyanide, K,^i(CN)^. Then 
add solution of potassium hydroxide in considerable quantity 
and bromine water, and warm. The nickel is completely pre- 
cipitated as black nickelic hydroxide, ^(OH)^. 



QUESTIONS AND EXERCISES. 

Name the commonest ore of manganese ; and give an equation descrip- 
tive of its reaction with hydrochloric acid.— Explain the formation of 
potassium permanganate, giving equations. — How do potassium man- 
ganate and permanganate act as disinfectants ? — What are the chief tests 
for manganese? — What are the chief uses of the compounds of cobalt? — 
How is cobalt analytically distinguished from nickel? — Mention appli- 
cations of nickel in the arts. — What is the usual color of nickel salts? 



DIRECTIONS FOR APPLYING THE ANALYTICAL REACTIONS DE- 
SCRIBED IN THE FOREGOING PARAGRAPHS TO THE ANALYSIS 
OF AN AQUEOUS SOLUTION OF SALTS CONTAINING ONE OF THE 
METALS, ZINC, MANGANESE, COBALT, NICKEL. 

First note the color of the solution : — 
Solutions of zinc salts are colorless. 



JSICKEL. 



145 



Solutions of manganous salts are colorless or very pale pink. 

Solutions of cobalt salts are rose red. 

Solutions of nickel salts are green. 

Add ammonium chloride, ammonia water until the liquid, after 
shaking, smells of this reagent, and then ammonium hydrosul- 
phide : — ^ 

A white precipitate -indicates zinc. 

A buff precipitate indicates manganous salt. 

A black precipitate indicates a cobaltous or a nickel salt. To 
distinguish between cobalt- and nickel, add ammonia water 
gradually to a portion of the original solution, without previously 
adding ammonium chloride. Cobalt gives a blue precipitate, 
soluble in excess and yielding a brownish solution which gradually 
darkens. Nickel gives a green precipitate which dissolves in 
excess yielding a blue solution. 

TABLE OF SHORT DIRECTIONS FOR APPLYING THE ANALYTICAL 
REACTIONS DESCRIBED IN THE FOREGOING PARAGRAPHS TO 
THE ANALYSIS OF AN AQUEOUS SOLUTION OF SALTS OF TWO OR 
MORE OF THE METALS, ZINC, MANGANESE, COBALT, NICKEL. 

If the solution is neutral, acidulate it with acetic acid ; if it 
is acid, add ammonia water until alkaline and then acidulate 
with acetic acid. Through the acetic acid solution pass hydrogen 
sulphide until the liquid, after shaking, smells of this gas ; 
filter. 



i 



Precipitate. 
Zn, Co, M. 
Boil with HCl and a little HNO3, add KOH in ex- 
cess ; filter. 


Filtrate. 

Mn. 

Add NH.OH 

in excess. 

Buff ppt. 


Precipitate. 
Co, Ni. 
Dissolve in HCl ; test for Ni as described 
in Keaction 4 (p. 144). If Ni absent, test 
solution for Co by borax bead (p. 142) ; if 
Ni present, filter off nickelic hydroxide, 
and test filtmte for Co by borox bead. 


Filtrate. 

Zn. 
Add 
NH.SH 
white ppt. 





I Ammoninm hydrosulphide added to an ammoniacal sohition con- 
taining amraoniuni chloride, is the group reagent for zinc, manganous, 
cobaltous, and nickel salts. 

10 



146 THE METALLIC RADICALS. 



ALUMINIUM : Al. Atomic weight, 26.9. 

Occurrence. — Aluminium is abundant in nature, occurring 
chiefly as silicate, in clays, slate, marl, basalt, and many other 
minerals. Mica or laminated talc consists chiefly of aluminium, 
iron, magnesium, and potassium silicates. Spinelle is mag- 
nesium aluminite. Corundum, sapphire, ruby, and amethyst are 
almost pure aluminium oxide. Emery is an impure aluminium 
oxide. Rotten stone is a soft, friable aluminium silicate containing 
a little organic matter. Cryolite is a double sodium and alumi- 
nium fluoride. 

The metal aluminium is obtained from the double sodium and 
aluminium chloride by the action of metallic sodium (the source 
of the chloride being the mineral bauxite, a more or less ferru- 
ginous aluminium hydroxide); also by the electrolysis of cryolite. 
It is readily attacked by various acids, but dilute sulphuric acid 
only acts upon it slowly. 

Aluminium is a remarkably light metal, and in consequence of 
this property and of the fact that it is practically unchanged by 
exposure to the air, it is now largely employed for the mountings 
for opera glasses, etc., and in making cooking utensils for the use 
of travellers. It readily forms alloys {see p. 209) with other me- 
tals. One part of aluminium fused with nine of copper gives alumi- 
nium bronze. Aluminium steel is a hard and tenacious alloy of 
iron with a little aluminium. 

Alum {Alumen, U. S. P.), aluminium and potassium sulphate, 
A1K(S0J2J I2H2O, may be obtained from alum shale, an alumi- 
nous schist (from oxkjtoc, schistos, divided) containing iron pyrites 
and some bituminous matter, by exposure to air ; oxidation in 
presence of moisture gives rise to the formation of aluminium sul- 
phate, ferrous sulphate, and silica, from the aluminium silicate 
and iron bisulphide, FeS2, (hon pyrites) originally present in the 
shale. The aluminium sulphate and ferrous sulphate are dissolved 
out of the mass by water, and potassium sulphate or chloride is 
added; on concentrating the liquid, alum crystallizes out, while 
the more soluble ferrous sulphate remains in the mother-liquor. 

Alum is more frequently prepared by directly decomposing the 
aluminium silicate in the calcined shale of the coal measures by 
means of hot sulphuric acid, potassium salts being added from 
time to time, until a solution is obtained which is sufliciently con- 
centrated to crystallize. The liquid, well agitated during cooling, 
dejiosits alum in minute crystals termed alum-fiour, which is after- 
ward recrystallized. 

Alums. — A series of double sulphates, analogous in composition 
to the alum just mentioned, have been prepared in which sodium 
or ammonium may take the place of potassium, and iron or 
chromium may take the place of aluminium. These salts are also 



ALUMINIUM. 147 

called alums; their general formula is M^^^M^(S0J2, I2H2O; ana 
they all crystallize in octahedra. The student should note that 
iron alum (below) and chrome alum (p. 168) do not contain 
aluminium. Ferri et Ammonii Sulphas, U. S. P., is iron alum, 
FeNH4(S04)2,12H,0. 

Ordinary alum commonly occurs in colorless, transparent, octa- 
hedral crystals, massed in lumps, which are roughly broken up 
for trade purposes, but which still exhibit the faces of octahedra. 
The commercial article sometimes contains potassium sulphate 
(potash alum), sometimes ammonium sulphate (ammonia alum). 

Note. — The aluminium atom is trivalent, and the formula for 
aluminium chloride is AICI3. The composition of aluminium 
sulphate is never represented by means of a formula with a single 
atom of aluminium, since this would involve writing Al(S04)i^. 
In order to avoid writing a fraction, the whole formula is doubled, 
when we get Al2(SOj3. 

- — Experiment, — Prepare alum by heating a small quantity of 
powdered pipeclay (aluininium silicate) with about twice its weight 
of sulphuric acid for sOme time, dis'solving the resulting alumi- 
nmm sulphate and excess of sulphuric acid in water, and add- 
ing potassium carbonate to the clear filtered solution until, after 
well stirring, the excess of acid is neutralized. (If too much car- 
bonate be added, the aluminium hydroxide which is precipitated 
when the carbonate is first poured in will not be redissolved even 
on thorough mixing. Perhaps the readiest indication of neu- 
trality in this and similar cases is the presence of a small quantity 
of precipitate after stirring and warming the mixture.) On 
evaporating the clear solution, crystals of alum are obtained. 

Aluminium Sulphate or '^ Alum-cake,^ ^ A\^(^0^.^, IGH^O, pre- 
pared from natural silicates in the manner just described, is a 
common article of trade, serving most of the manufacturing pur- 
poses for which alum was formerly employed. (Alumini Sulphas, 
U.S.P.). 

Dried Alum (Alumen Exsiccatum, U. S. P.), is potassium alum 
from which the water of crystallization has been expelled by heat. 
By calculation from the formula, it will be found that alum con- 
tains between 45 and 46 percent, of water. Dried alum rapidly 
reabsorbs water from the air, and is slowly but completely soluble 
in water. At temperatures above 400° F.(204.4° C), ammonium 
alum is decomposed, water, ammonia, and sulphuric anhydride 
escaping, and pure aluminium oxide, AlgO^, remaining. 

Roche alum, or Rock alum (Fr. roche, rock), is the name of an 
impure native variety of alum containing iron. The article sold 
under this name is generally an artificial mixture of common alum 
with ferric oxide. 



148 THE METALLIC RADICALS. 

Analytical Reactions of Aluminium Salts. 

1. To a solution of an aluminium salt (alum, for example, 
which contains aluminium sulphate) add ammonium hydro- 
sulphide; a white gelatinous precipitate of aluminium hydrox- 
ide is produced: — 

Al2(S04)3 - 6XH,SH ^ m,0 = 2A1(0H)3 -h ^{:^R,)SO, + GH^S 

2. To a solution of alum add ammonia water ; aluminium 
hydroxide is precipitated : add excess of ammonia water ; the 
precipitate is practically insolube. 

Principle of Dyeing by help of Mordants. — Precipitated 
aluminium hydroxide has great affinity for vegetable color- 
ing-matters, and also for the fibre of cloth. Repeat experi- 
ment 2, but before adding the ammonia water, introduce into 
the test-tube some decoction of logwood, solution of cochineal, 
or other solution of an animal or vegetable coloring-matter. 
Now add the reagent and set the tube aside for the precipitate 
to settle; the latter takes down with it all the coloring-matter. 
In dye works, the undyed fabrics are treated with solutions of 
aluminium acetate in such a manner as to deposit alummium 
hydroxide within their fibres, and are then passed through 
the coloring solutions, from which the hydroxide abstracts 
coloring-matter. Some other metallic hydroxides, notably 
those of tin and iron, resemble aluminium hydroxide in this 
respect ; they are termed mordants (from mordens biting) ; 
the substances they form with coloring-matters are called 
lakes. 

3. To a solution of alum add solution of potassium hydrox- 
ide; alumjnium hydroxide is precipitated. Add excess of the 
reagent,' and agitate ; the precipitate dissolves. 

Aluminium hydroxide may be precipitated from this solu- 
tion by neutralizing the potassium hydroxide with hydro- 
chloric acid, and adding ammonia water until, after shaking, 
the mixture smells of ammonia; or by adding a sufficient 
quantity of solution of ammonium chloride to the alkaline 
liquid, and boiling until ammonia is no longer evolved. 

4. To a solution of alum add solution of potassium or 
sodium carbonate. A precipitate of aluminium hydroxide 
(Alumini Hydroxidum, U. S. P.) is produced, and carbonic, 
anhydride escapes: — 

Al,(SO,)3+3K,C03+3Hp=2Al(OH)3+3K,SO,+3CO, 



IRON. 149 

QUESTIONS AND EXERCISES. 

Enumerate the chief natural compounds of aluminium? — Write down a 
formula which will represent either of the alums. — Which alum is official, 
and commonly employed in the arts ? — State the source and explain the 
formation of alum. — -What is the crystalline form of alum ? — Calculate 
how much dried alum is theoretically producible froi^a 100 pounds of 
potassium alum. Ans., 54 lb. 7 oz. — Show that ordinary ammonium alum 
is capable of yielding 11.269 percent, of aluminium oxide. — Why are 
aluminium compounds used in dyeing? — How are aluminium salts ana- 
lytically distinguished from zinc salts ? 



IRON : Fe. Atomic weight, 55.5. 

Sources. — Compounds of iron are abundant in nature. Mag- 
netic Iron Ore, or Loadstone {Lodestone or Leadstone, from the 
Saxon loedan, to lead, in allusion to its, or rather, to the use of 
magnets made from it, in navigation), FegO^, is the chief ore from 
which Swedish iron is made. Much of the Russian iron is made 
from Specular Iron Ore (from speculum, a mirror, in allusion to 
to the lustrous nature of the crystals of this mineral); this and 
Red Hcematite (from aljia, haima, blood, so named from the color 
of its streak), an ore raised in Lancashire, are composed of ferric 
oxide, Fc^Og. Brown Hcematite, an oxyhydroxide, Fe20(OH)4, 
is the source of much of the French iron. Needle iron ore, or 
gothite, is also an oxyhydroxide, FeO(OH). Spathic Iron Ore (from 
spatha, a slice, allusion to the lamellar structure of the ore) is 
ferrous carbonate, FeCOg. An impure ferrous carbonate forms 
the Clay Ironstone, whence most of the English iron is derived. 
The chief Scotch ore is also an impure carbonate, containing much 
bituminous matter: it is known as Black Band. Iron Pyrites 
(from TTvp, pur, fire, in allusion to the production of sparks when 
sharply struck, ) FeSa, i^ ^ yellow, lustrous mineral, now largely 
employed as a source of sulphur. As met with in coal, it is 
commonly termed coal brasses. Ferrous bicarbonate, chloride and 
sulphate, sometimes occur in springs, the waters of which are 
hence termed chalybeate [chalybs, steel). 

Manufacture of Iron. — The manufacture of iron from its ores is 
carried on as a continuous process by means of the blast-furnace, a 
high structure built with fire-bricks. Most manufacturers employ 
a mixture of ores — the oxide ores simply in the condition in 
which they are mined, and some other ores after the preliminary 
operation of roasting, or strongly heating in air, to convert thorn 
into oxide. The mixed ores, along with coal and limestone, are 
fed into the top of the blast-furnace, while a current of heated air, 
forced in at the bottom under considerable pressure, causes the 
coal to burn rapidly, and thereby maintains a very high tempera- 
ture inside the furnace. In the course of their passage down from 



150 THE METALLIC RADLCALS. 

the top, the iron oxides give up their oxygen to form carbonic 
anhydride, and the reduced iron trickles down and collects at the 
bottom of the furnace. On its way down, the melted metal is 
protected from the oxidizing action of the hot-air blast by the 
slag, a fusible glassy substance which is produced by the interac- 
tion of the limestone with the sand and clay present as impurities 
in the ores. The fused slag collects in a layer which lies on the 
top of the melted iron and is occasionally drawn off. The iron 
is also drawn off from time to time, and is allowed to flow into 
narrow branched gutters moulded in sand, where it cools and 
solidifies, and is afterward broken up into fragments which con- 
stitute 7:* /^^-/ro;? — the form in which cast-iron is met with in com- 
merce. 

The cast-iron thus produced may be converted into ivrought- 
iroti by burning out the 4 or 5 percent, of carbon, silicon, and 
other impurities present, by oxidation in a furnace — an operation 
termed puddling. Steel is iron containing from 1 to 2 percent, of 
carbon. It is now made by the Bessemer process, which consists 
in burning out from cast-iron the variable amount of carbon it 
contains, and then adding melted iron containing a known pro- 
portion of carbon. The official iron {Fen-um, U. S. P.), is 
''metallic iron, in the form of fine, bright and non-elastic wire," 
a form in which iron is conveniently employed for conversion into 
its compounds. In the form of a fine powder, metallic iron is 
employed as a medicine (see p. 162). 

Propeiiies. — The specific gravity at 15. 5 C, of pure iron is 
7. 844 ; of the best bar, or wrought iron 7. 7. Its color is bluish 
white or gray. Bar iron requires the highest heat of a wind-ftir- 
nace for fusion, but below that temperature it assumes a pasty 
consistence, and in that state two pieces may be joined or welded 
(Germ, welhn, to join) by the pressure of blows from a hammer. 
A little sand thrown upon the hot metal facilitates this operation 
by forming with the superficial coating of oxide of iron a fusible 
slag, which is dispersed by the blows: the purely metallic surfaces 
are thus better enabled to come into thorough contact and enter 
into perfect union. Iron is highly ductile, and of all common 
metals possesses the greatest amount of tenacity. At a high tem- 
perature it burns in the air, forming black magnetic oxide. 
Ordinary iron rust is chiefly brown ferric hydroxide or oxhydrox- 
ide, with a little ferrous oxide and carbonate; it is produced by 
action of the moisture and carbonic anhydride of the air and sub- 
sequent oxidation. Steam passed over iron heated to redness 
yields hydrogen and magnetic oxide of iron. 

Quantivalence of Iron. Ferrous and Ferric Salts. — In its union 
with other elements and with radicals, to form salts, iron exhibits 
the property of combining with these in two proportions so as to 
give rise to two distinct sets of salts. In one of these sets, iron 
appears as a bivalent metal, the formula of the chloride being 



FERROUS SALTS. 151 

FeCl2, that of the sulphate, FeSO^, etc. In the other set, iron is 
trivalent, the formulae of the chloride and sulphate being FeClg 
and Fe2(S0 J3 respectively. These two sets of salts are regarded 
as related to the two basic oxides of iron, FeO and FCgOg (the 
place of the oxygen of the basic oxides being taken by acid 
radical), and they are known as ferrous and ferric salts respec- 
tively. Thus the ''lower" chloride, FeClg (or chloride contain- 
ing the smaller proportion of chlorine) is ferrous chloride, while 
the ' ' higher ' ' chloride, FeClg (or chloride containing the larger 
proportion of chlorine), is ferric chloride. When the analytical 
reactions of iron salts come to be studied, it will be found that 
those of the ferrous and ferric salts are quite different from each 
other and enable the student to ascertain in which of the two 
forms of combination the iron is present. This feature of forming 
two separate sets of salts is not peculiar to iron, but is met with 
in the cases of copper, mercury, and various other metals. The 
terminations ous andic are employed in these cases in a consistent 
manner, the former always denoting the compound containing the 
smaller, and the latter that containing the larger proportion of 
oxygen (in the case of the basic oxides) and of acid radical (in 
the case of the salts). 



FERROUS SALTS. 

Ferrous Sulphate. Iron Proto sulphate. 

Experiment 1. — Place iron (small tacks) in dilute sulphuric 
acid, accelerating the action by heat until effervesceuce ceases. 

Fe + H,SO, = FeSO, + H^ 

Iron Sulphuric acid Ferrous sulphate Hydrogen 

The solution contains ferrous sulphate, and will yield crys- 
tals of that substance, FeSO,, TH^O, {Ferri Sulphas, U. S. P.), 
on cooling or on further evaporation ; or if the hot con- 
centrated solution be poured into alcohol, the mixture being 
well-stirred, the sulphate is at once thrown down in minute 
crystals (Ferri Sulphas Granulatus, U. S. P.). At a tem- 
perature of 212° F. (100° C), ferrous suli)hate loses six- 
sevenths of its water, and becomes Ferri Sulphas Exsiccatus, 
U. S. P. 

Other Sources of Ferrous Sulphate. — In the laboratoiy, ferrous 
sulphate is often obtained as a by-product in making hydrogen 
sulphide (p. 100). In the manufacture of alum it occurs as a by- 
product in the decomposition of the aluminous shale, as already 
noticed (p. 146). 



152 



THE METALLIC RADICALS. 



A ten percent, solution of ferrous sulphate in distilled water 
which has been previously boiled, constitutes "Ferrous Sulphate 
Test Solution," U. S. P. ^ "This solution should be freshly pre- 
pared immediately before use," because of its liability to absorb 
oxygen with formation of ferric oxysulphate {see below). 

Notes. — Ferrous sulphate was formerly termed green vitriol. 
Vitriol (from vitrum, glass) w^as originally the name of any trans- 
parent crystalline substance: it was afterward restricted to the 
sulphates of zinc, iron and copper, w^hich were, and still are occa- 
sionally, known as white, green and blue vitriol respectively. 
Copperas (probably originally Copper-rust, a term applied to ver- 
digris and other green incrustations of copper) is another name 
for this iron sulphate, sometimes distinguished as green copperas, 
copper sulphate being blue copperas. Exsiccated ferrous sulphate 
is a constituent of Pilula Aloes el Ferri, U. S. P. Ferrous sul- 
phate forms a light green double salt with ammonium sulphate 
(ammonium ferrous sulphate, (NHJ^jSO^, FeSO^, 6H2O). 

Ferrous sulphate, when exposed to the air, gradually becomes 
brown through absorption of oxygen, ferric oxysulphate, 
Fe,0(S0j2, being formed. The latter is not completely dis- 
solved but is decomposed by water, with the formation of a still 
lower insoluble oxysalt (Fe^-SOJ, and soluble ferric sulphate: 
bYefi{^0,\ = Fe.O.SO, + 3Fe2(SC,)3. 

Iron heated with undiluted sulphuric acid yields sulphurous 
anhydride and ferrous sulphate: 

Fe + 2H2SO, = FeSO, + SO, + 2H O 



Ferrous Carbonate. Iron Carbonate. 

Experiment 2. — To a hot solution of ferrous sulphate, in a 
test-tube, add a solution of sodium bicarbonate, which has 
been prepared with water at a temperature not exceeding 
50° C; a white precipitate of ferrous carbonate, FeCO^, is 
produced which rapidly becomes light-green, bluish green, and 
on standing for some time, reddish-brown, owing to absorption 
of oxygen; carbonic anhydride is evolved, and ferric oxyhy- 
droxide is formed. 

FeSO, -h 2N2HCO3 = FeCO, + 

Ferrous Sodium Ferrous 

sulphate bicarbonate carbonate 

Saccharated Ferrous Carbonate. — The above precipitate of fer- 
rous carbonate, rapidly washed with boiling distilled water, and 
then mixed with sugar and quickly dried— all possible precautions 
being taken to avoid prolonged exposure to air — forms saccharated 
ferrous carbonate {Ferri Carbonas Saccharatus, U. S. P.). This is 
probably a mixture of ferrous carbonate, etc., with sugar; a com- 



Na.,SO, + H,0 


+ CO, 


Sodium Water 


Carbonic 


sulphate 


anhydride 



FERROUS SALTS. 153 

2^ound 'known as iron sucrate, containing about 48.5 percenL of 
iron, is obtained by pouring a solution of cane-sugar and ferric 
chloride into a slight excess of sodium hydroxide; a reddish-brown 
crystalline precipitate is produced. Iron maltosate is an analogous 
compound. 

Notes. — The red powder formerly termed Carbonate or Subcar- 
bonate of Iron {Ferri Carbonas or Ferri Subcarbonas) was ferrous 
carbonate washed and dried with free exposure to air, the product 
thus, by the absorption of oxygen and the elements of water, and 
the elimination of carbonic anhydride, becoming ferric oxyhydrox- 
ide, a compound which will come under notice subsequently. 
Ferrous carbonate is said to be more easily dissolved in the 
stomach than any other iron preparation. It so easily oxidized, 
that it must be washed with water free from dissolved air, and 
then mixed with the sugar (which protects it from oxidation) as 
quickly as possible. In making the official compound mixture of 
iron {Mistura Ferri Cimposita, U. S. P.), ''Griffith's mixture," 
the prepared ingredients, including the potassium carbonate, 
should be placed in a bottle of the required size, space being left 
for the solution of ferrous sulphate, which should be added last, 
the bottle immediately filled up with the rose-water and securely 
corked; the minimum of oxidation is thus ensured. The propor- 
tions ordered in the official mixture are almost three times the for- 
mula weight of potassium carbonate for once that of ferrous sul- 
phate; hence, as the ferrous carbonate decomposes, the carbonic 
anhydride produced does not necessarily escape, but converts the 
potassium carbonate into bicarbonate. Pilula Ferri Carbonatis, 
U S. P., Iron Fill or ''Blaud's Pill," is prepared with granulated 
ferrous sulphate and potassium carbonate. 

FeSO, + K2CO3 = FeCOs' + K^SO, 



Ferrous Arsenate. Iron Arsenate 
See under Arsenic (p. 174). 

Ferrous Phosphate. Iron Phosphate. 

Experiment 3. — To a hot solution of ferrous sulphate in a 
test-tube add a hot solution of sodium phosphate and a small 
quantity of a solution of sodium bicarbonate ; ferrous phos- 
phate is precipitated. 

3FeS04 + 2Na,HP0, + 2NaHC0, = 

Ferrous sulphate Sodium phosi)hate Sodium bicarbonate 

Fe3(P0,), + 8Na,S0, + 2H,0 -f- 200.. 
Ferrous sulphate Sodium sulphate Water Carbonic anhvdi- • 



154 THE METALLIC RADICALS. 

The addition of the sodium bicarbonate is to ensure the absence 
of free suli)huric acid from the solution. Sulphuric acid dissolves 
ferrous phosphate, and it is impossible to prevent the liberation 
of some sulphuric acid, if only the ferrous sulphate and sodium 
phosphate be employed without the sodium bicarbonate. Ferrous 
phosphate is white but soon becomes oxidized and is then slate- 
blue. It was formerly included in the United States Pharmaco- 
poeia, and is still official in the British Pharmacopoeia. 

Ferrous Sulphide. Iron Sulphide. 

Experiment 4. — Mix sulphur in a test-tube with about twice 
its weight of irou filings and strongly heat the mixture in the 
Buusen flame (or heat in an earthen crucible in a furnace) ; 
ferrous sulphide, FeS, is formed. When the product is cold, 
add water to a small portion of it, and then a few drops of 
sulphuric acid ; hydrosren sulphide, H,S, recognizable by its 
odor, is evolved. ^FeS^— H,SO, = FeSO, -f H,S. 

Sticks of sulphur pressed against a white-hot bar of cast-iron 
give a pure form of ferrous sulphide ; or melted sulphur may be 
poured into a crucible of red-hot iron nails, when a quantity of 
fluid ferrous sulphide is at once formed and may be poured out on 
a slab. 

Hydrous Ferrous Chloride. Iron Chloride. 

Experiment 5. — Digest iron tacks or wire, in a test-tube, in 
hydrochloric acid ; hydrogen escapes, and the solution on cool- 
ing, or on evaporation and cooling, deposits crystallized ferrous 
chloride, FeCl,, 4Hp. 

Anhydrous Ferrous Chloride. — See p. 156. 

Ferrous Iodide. Iron Iodide. 

Experiment 6. — Place a piece of iodine, about the size of a 
pea, in a test-tube, with a small quantity of water, and add a 
few iron filings, or small nails, or some iron wire. On gently 
warminsf, or merely shaking if longer time be allowed, the 
iodine disappears, and on filtering, a clear light-green solution 
of ferrous iodide, Fel,„ is obtained. On evaporation, the 
solid iodide remains. 

Solid ferrous iodide contains about 18 percent, of water of ciys- 
tallization and a little iron oxide. It is deliquescent and liable to 
absorb oxygen from the air with formation of insoluble ferric oxyio- 
(liilf ( : hydroxyiodide. Ferrus iodide thus oxidized may be 



FERRIC SALTS. 



155 



purified by re-solution in water, addition of a little m( iC iodine 
and some iron, warming, filtering, and evaporating as Detore. 
Syrup of ferrous iodide {Si/rupus Ferri lodidi, U. S. P.), has al- 
ready been mentioned on p. 37. Syrup of ferrous iodide which 
has become brown may usually be restored by immersing the 
bottle in a water-bath and slowly warming. 

In making PilulcB Ferri lodldi, U. S. P., reduced iron (see. p. 
162) is used. 

Ferrous Bromide, FeBrj, occasionally used in medicines may 
be made in a similar way. Its solution in water or syrup is light 
green. 

FERRIC SALTS. 

Anhydrous Ferric Chloride. (Iron Perchloride).^ 

Experiment 7. — Pass chlorine (generated from black man- 
ganese oxide and hydrochloric acid in a flask) through con- 
centrated sulphuric acid contained in a small wash-bottle (to 
dry the gas) and then, by means of a glass tube, to the bot- 

FiG. 31. 




Preparation for anhydrous ferric chloride. 



torn of a test-tube containing twenty or thirty small iron tacks 
(or "a flask containing two or three ounces of them — see Fig. 
31), the latter being kept hot by a gas-flame; ferric chloride, 
FeClg, is formed and condenses in the upper part of the tube 

^ The prefix j^er (and hyper) used here and elsewhere is from vnep. hyper. 
over, or above, and in this case, indicates the higher clUoride of iron : 
that is, iron ]>erchloride is the iron chloride which contains the hirgor 
proportion of chlorine. 



156 



THE METALLIC RADICALS. 



or fiask as a mass of small, dark, irredescent crystals. When a 
tolerably thick crust of the salt is formed, break off the part 
of the glass containing it, being careful that the remaining cor- 
roded tacks are excluded, and place it in ten to twenty times 
its weight of water : the resulting solution, poured off from any 
pieces of glass, is a nearly neutral solution of ferric chloride, 
and may be employed for analytical reactions. 

Precaution. — The above experiment must be conducted in the 
open air, or in a fume-cupboard. 

Anhydrous Ferrous Chloride. — In breaking up the vessel, scaly 
crystals of this substance, FeClj, of a light and buff color, will be 
observed adhering to the nails. 

Note. — Solution of ferric chloride gives off some hydrochloric 
acid on boiling, while a darker-colored solution of ferric oxy- 
chloride remains. 



Solution of Ferric Chloride. 

Experiment 8. Through a portion of the solution of ferrous 
chloride, prepared in experiment 5, pass chlorine gas ; the 
ferrous chloride is converted into ferric chloride, The excess 
of chlorine dissolved by the liquid in this experiment may be 
removed by ebullition; but the ferric chloride is liable to be 
slightly decomposed. (^See above). The free chlorine is 
better carried off by passing a current of air through the 
liquid for some time. 

^^ Experiment 9. To a portion of the solution of ferrous 
chloride, prepared in experiment 5, add a little hydrochloric 
acid ; heat the liquid, and drop in nitric acid until the black 
color at first produced, disappears ; the resulting reddish- 
brown liquid is a solution of ferric chloride. 



SFeCl^ + HNO3 + 3HC1 = 


SFeCls + NO -f 2H2O 


Ferrous Nitric Hydrochloric 


Ferric Nitric Water 


chloride acid acid 


chloride oxide 



The black substance is a compound produced by the interac- 
tion of nitric oxide, NO, with some ferrous salt; its composition 
is 2FeS0^+N0; it is decomposed by heat. 

Liquor Ferri Chloridi, U. S. P. , is a solution of ferric chloride 
prepared by pouring a solution of ferrous chloride into a sufficient 
quantity of nitric acid contained in a capacious vessel, evaporating 
until the liquid is free from nitric acid, and adjusting the solution 
so as to contain 10 percent, of iron. 1 volume with 3 of alcohol, 
gives Tinctura Ferri Chloridi, U. S. P. 

Note. — The alcohol in the latter preparation does not act either 
as a special solvent or as a preservative — the offices usually per- 



FERRIC SALTS. 1 .' / 

formed by alcohol in U. S. P. preparations — and, as a matte i •; 
fact, unless the liquid contain excess of acid, it decomposes the 
ferric chloride and causes the formation of an insoluble ferric oxy- 
chloride. Even if the tincture be acid, it slowly loses color, 
ferrous chloride and ethereal compounds containing chlorine being 
formed. Liquor Ferri Chlorldi is not liable to such decomposition 
and such variation in characters. 

Solution of Ferric Chloride, when evaporated, yields a mass of 
yellow crystals having the composition FeClg, 6H2O, or, under 
other conditions, red crystals represented by the formula 2FeCl3, 



Ferric Sulphate (formerly called Iron Persulphate).^ 

- Experiment 10. — Dissolve about three-quarters of an ounce 
of ferrous sulphate and about a fifth of this weight of sulphuric 
acid in an ounce and a half of water in an evaporating-dish, 
heating the mixture and dropping in nitric acid until the 
black color at first produced, disappears. The resulting 
liquid, when made of a certain prescribed strength, is solution 
of ferric sulphate (^Liquor Tersulphatis, U. S. P.), a heavy, 
dark-red liquid. 

6FeS0,+ 3H,S0, + 2HNO3 = ^Fe/SO,),, + 2N0 + 4H,0 

Ferrous Sulphuric Nitric Ferric Nitric Water 

sulphate acid acid sulphate oxide 

The black color, as in experiment 9, is due the formation of a 
compound by the interaction of ferrous salt with nitric oxide. 

Ferric Hydroxide and Ferric Oxyhydroxide. 

Experiment 11. — Pour a portion of the solution of ferric 
sulphate into excess of ammonia water ; ferric hydroxide, 
Fe(0H)3, Ferri Hydroxidum, U. S. P., is precipitated. Wash 
the precipitate by decantation or on a filter, and dry it on 
a water-bath; ferric oxyhydroxide, FeO(OH), remains. 

Fe,(S0j3 + 6NHPH = 2Fe(OH)3 + 3(NHJ,S0, 

Ferric Ammonia Ferric Ammonium 

sulphate water hydroxide sulphate 

Fe(OH), = FeO(OH) + H,0 

Ferric hydroxide Ferric oxyhydroxide Water 

Either of the other alkalies (caustic potash or soda) would pro- 
duce a similar reaction. 

^ The name persulphate cannot now be applied consistently to this 
substance. The persulphate form a definite series of salts derived from 
persulphuric acid. H2S2O8. Ferric sulphate is simply the sulphate cor- 
responding to the higher basic oxide of iron — ferric oxide, Fo.'Os, formerly 
called sesquioxide, and sometimes peroxide, of iron. 



158 THE METALLIC RADICALS. 

Ferric hydroxide is an antidote in cases of arsenical poisoning, 
if administered directly after the poison has been taken. It con- 
verts the soluble arsenous acid, H3ASO3, into insoluble ferrous 
arsenate: — 

4Fe(OH)3 + 2H3ASO3 = Fe3(AsOJ, + 8H,0 + FeCOH)^ 

Ferric hydroxide becomes converted into oxyhydroxide, when 
dried, and has then less action on the arsenous acid. Even the 
moist recently prepared hydroxide loses much of its action as soon 
as it has changed into one of the oxyhydroxides, FeiO.XOH)^, a 
change which will occur though the hydroxide be kept under 
water (W. Procter, jun.). According to T. and H. Smith, this 
decomposition occurs gradually, but in an increasing ratio; so 
that after four months the power of the moist mass is reduced to 
one-half and after five months to one-fourth. 

A ferric oxycarbohydroxide, Fe,0C03(0H)g, has been obtained. 

Ferric Oxide. 

Ferric oxyhydroxide, FeO(OH), decomposes when heated 
to low redness, ferric oxide, Fe2Q3, remaining. 

2FeO(OH) = Fe^^ + H,0 

- Experiment. 12. — Roast a crystal or two of ferrous sulphate, 
mixed with a small quantity of sulphur to aid the reduction, 
in a small crucible until fumes are no longer evolved; the 
residue is a variety of ferric oxide, know^n in trade as red 
oxide of iron, colcothar, crocus, mineral rouge, Venetian red, etc. 
It has sometimes been used in pharmacy in mistake for the 
oxyhydroxides, from w^hich it differs not only in composition 
but in the important respect of being almost insoluble in 
acids. 

Ferric Acetate. Iron Acetate. 

Experiment 13. — Digest recently-prepared, washed, and 
drained ferric hydroxide in glacial acetic acid; ferric acetate, 
Fe(C2H302)3, is produced: — 

Fe(OH), -f SHC^Hp^ = Fe(C2H302)3 + SH^O 

Ferric hydroxide Acetic acid Ferric acetate Water 

The "Scale" Compounds of Iron. 

Experiment 14. — Repeat experiment 11, introducing some 
solution of citric or tartaric acid or of potassium bitartrate 
iiMo iiK u>mc sulphate solution before adding it to the alkali 



FERRIC SALTS. 159 

(caustic soda, caustic potash, or ammonia), and notice that 
now no precipitation of ferric hydroxide occurs. The non- 
production of precipitates is due to the formation of double 
compounds, which remain in solution along with alkali-metal 
sulphate. Such ferric compounds, made by mixing certain 
prescribed proportions of recently prepared ferric hydroxide 
(from which all soluble sulphate has been removed by wash- 
ing), with the respective acids (tartaric or citric) or acid salts 
(potassium bitartrate), etc., evaporating the solutions to a 
syrupy consistence and then spreading on smooth plates to 
dry, form scale preparations such as Ferri et Ammonii Citras, 
U. S. P., and Ferri et Fotassii Tartras, U. S. P. A mixture 
of ferric citrate with ammonium citrate and quinine citrate 
yields, by similar treatment, the well-known scales of Ferri et 
Quiyiince Citras, U. S. P. 

Specimens of these substances may be prepared by attending to 
the following details. It is essential, first, that the ferric hydrox- 
ide be thoroughly washed, or an insoluble oxysulphate will be 
formed; secondly, that the ferric hydroxide be rapidly washed, or 
an insoluble ferric oxy hydroxide will be produced; thirdly, that 
the whole operation be conducted quickly or reduction to green 
ferrous salt will occur; fourthly, that the solutions of the salts be 
not evaporated at a high temperature, or decompositon will take 
place; and, fifthly, that excess of ferric hydroxide be employed. 

In making the scale compounds, the ferric hydroxide is in each 
case freshly made from solution of ferric sulphate by precipitation 
with ammonia water: — 



Fe,(S0j3 + 6NH3 + 6H2O - 


= 2Fe(OH)3 + 3(NH,), SO, 


Ferric Ammonia 


Ferric Ammonium 


sulphate water 


hydroxide sulphate 



the solution of ferric sulphate being made of a definite concentra- 
tion from a known weight of ferrous sulphate. The reason for 
adopting this course is, that ferric hydroxide cannot be dried with- 
out decomposing and becoming insoluble as explained on p. 158, 
and therefore cannot be weighed. This definite solution of ferric 
sulphate {Liquor Ferri Tersulphatis, U. S. P.), is made as already 
described. 

Ferri et Ammonii Citras, U. S. P. — Ferric hydroxide is dis- 
solved in solution of citric acid, ammonia water added, and the 
whole evaporated to dryness. 

To prepare the ferric hydroxide, dilute U) fiuidouncos of the 
above solution of ferric sulj)hate with about a quart of water; pour 
this into 2 pints of water containiui!; excess of anmionia water. 
(If the opposite course were ado})ted — the alkaline liquid poured 
into the ferric solution — the precipitate would contain ferric oxy- 



160 THE METALLIC RADICALS. 

sulphate, or hydroxysulphate, which interferes with the brilliancy 
of the scales. ) Thoroughly stir the mixture (it will smell strongly 
of ammonia if enough of the latter has been used), allow the pre- 
cipitate to subside, pour away the supernatant liquid, add more 
water, and repeat the washing until a white precipitate of barium 
sulphate is no longer produced on the addition of solution of ba- 
rium chloride or nitrate to a little of the washings. Collect the 
ferric hydroxide oil a filter, drain, and add it, while still moist, 
to a solution of 4 ounces of citric acid in 4 of water, placed in an 
evaporating-basin on a water-bath ; stir frequently, until nearly 
the whole of the hydroxide has dissolved, or until the acid is 
fully saturated with the hydroxide and some of the latter remains 
undissolved. To the mixture, when cold, add 5J fluidounces of 
ammonia water, filter, evaporate on a water-bath to the consist- 
ence of syrup, spread thinly on sheets of glass, and dry (at a 
temperature not exceeding 100° F., 37. 8° C). The product scales 
oflf the glass in deep-red transparent laminae. 

Note. — The chemical composition of iron and ammonium citrate 
is approximately FeO(XHj2C6H.O.. Compounds which exhibit 
an analog^' in composition are found in bismuth and ammonium 
citrate, BiO(XHJ.^CgH.07, and antimony and potassium tartrate, 
SbOKC,H,0,. 

Ferri et Quinince Citras Solubilis, U. S. P. — Ferric hydroxide and 
pure quinine are dissolved in solution of citric acid, ammonia 
water added, and the whole evaporated to dryness. The product 
contains ferric citrate, quinine citrate, and ammonium citrate. 

The ferric hydroxide is obtained from 9 fluidounces of the 
solution of ferric sulphate, with all the precautions described 
under Ferri et Ammonia Citras. 

While the ferric hydroxide is being washed, prepare the qui- 
nine by dissolving 2 ounces of quinine bisulphate in 16 ounces of 
distilled water, and to the clear liquid add ammonia water, well 
mixing the product by stirring, until the whole of the quinine is 
precipitated (this is the case when the mixture, after thorough 
agitation, smells of ammonia). Collect the precipitate on a filter, 
let it drain, and wash away adhering solution of ammonium sul- 
phate by passing through it about three pints of distilled water. 

The ferric hydroxide and quinine being now washed and 
drained, dissolve the former, and afterward the latter, in a solu- 
tion of 6 ounces and 60 grains of citric acid in an equal weight of 
distilled water, the acid liquid being warmed on a water-bath, and 
portions of the precipitates stirred in as fast as solution is effected. 
Let the solution cool ; add, in small quantities at a time, 3 fluid- 
ounces of ammonia water, diluted with 4 fluidounces of dis- 
tilled Avater ; stir briskly, allowing the quinine which separates 
with each addition of ammonia to dissolve before the next addition 
is made ; filter the solution; evaporate it to the consistence of a 



FERRIC SALTS. 161 

thin syrup; dry the latter in thin layers on flat porcelain or glass 
plates at a temperature of 100° F. (37.8° C); remove the dry 
scales of Soluble Iron and Quinine Citrate. Ferri et Quinince 
Citras, U. S. P., is a similar, but somewhat less readily soluble 
preparation. 

Ferri et Potassii Tartras, U. S. P. — Ferric hydroxide is dis- 
solved in solution of potassium bitartrate, and the whole evapo- 
rated to dryness. 

The ferric hydroxide obtainable from 10 fluidounces of the official 
solution of ferric sulphate by the action of ammonia, in the 
manner detailed under Ferri et Am7nonii Citras, is mixed (in a 
porcelain dish), while still moist but well drained, with 3 ounces 
and 146 grains of potassium bitartrate. The whole is set aside for 
about twenty-four hours, and then heated on a water-bath to a 
temperature not exceeding 140° F. (60° C); a pint and a half of 
distilled water is then added, and the mixture is kept warm until 
nothing more will dissolve, filtered, evaporated at a temperature 
not exceeding 140° F. (60° C.), (greater heat causes decomposition), 
and when the mixture has the consistence of syrup, spread on 
sheets of glass and allowed to dry (in any warm and open place at 
a temperature not exceeding 100° F., 37.8° C). The dry salt is 
thus obtained in scales. It should be kept in well-closed bottles. 

In the United States Pharmacopoeia Ferri Citras, Ferri et Strych- 
nincE Citras, and Ferri et Ammonii Tartras are included. Ferric 
citrate dissolves slowly in cold, but readily in warm water. 
Ferric phosphate, FePO^, when freshly precipitated, is soluble in 
solutions of citrates of the alkali-metals, and the solutions on evapo- 
ration on glass plates yield scales. Ferri Phosphas Solnbilis, 
U. S. P. , is a preparation of this kind : it may be obtained by the 
interaction of sodium phosphate with a solution of ferric citrate 
and evaporation of the solution at a temperature which should 
not exceed 140° F. (60° C). It forms thin, bright green trans- 
parent scales. Ferri Pyrophosphas Solubilis is also official. 

The foregoing are the official scale preparations of iron. Many 
others of similar character might be formed. Few of them crys- 
tallize or give other indications of definite chemical composition. 
Their properties are only constant so long as they are made with 
unvarying proportions of the constituents. A crystalline, ferrous 
tartrate, FeC^H^Op, and an acid ferrous citrate, FeHC^HjO^, iA.fi, 
have been obtained by the interaction of iron and the respec- 
tive acids in hot water. They occur as white gritty masses of 
microscopic crystals. A sodlo-ferrous citrate, FeNaC^H-O^, and 
hydroxy citrate, FeOHNa2C6H50^, may be obtained in scales. 

Wine of iron, or "Steel" wine (Vinum Ferri, U. S. P.), is a 
solution of Iron and Ammonium Citrate in white wine, with Tinc- 
ture of sweet Orange Peel and Syrup added. Bitter Wine of Iron 
( Viniun Ferri Amaruni, U. S. P.), is a similar solution of soluble 
Iron and Quinine Citrate. 

XI 



]<)2 



THE METALLIC RADICALS. 



Ferric Nitrate. 

Experiment 15. — Place a few irou tacks in dilute nitric acid 
a_id set aside ; solution of ferric nitrate, Fe(N03)3, is formed. 



Fe 

Iron 



4HNO3 

Nitric acid 



Fe(N03)3 

Ferric nitrate 



2H,0 + NO 
Water Nitric oxide 



Ferric nitrate and ferric acetate unite to form various aceto- 
nitrates, among which is one having the formula Y^.J^Q^^O^^ 
NO3OH, 4H2O, and crystallizing in hard, shining brownish-red 
prisms. 

Reduced Iron. 

Experiment 16. — Pass pure hydrogen (which has been dried 
by passing it over pieces of calcium chloride contained in a 
tube or through sulphuric acid in a wash-bottle) over a small 
quantity of ferric oxide, Fe203, or ferric oxyhydroxide, 




Preparation of reduced iron. 

Fe(OH), contained in a tube placed horizontally, the powder 
being kept hot by a gas-flame ; oxygen is removed by the 
hydrogen, steam escapes at the open end of the tube, and after a 
short time, when moisture ceases to be evolved, metallic iron, 
in a state of fine division, remains. (^See Fig. 32.) 



2Fe(3(OH) + 

Ferric oxyhydroxide 



3H, 



2Fe 

Iron 



4H,0 

■Water 



Hydrogen 

While still hot, throw the iron out into the air; it takes fire 
and foils to the ground as magnetic oxide, FCgO^. 

If ferric oxide is reduced in a strongly-heated iron tube in a 
furnace, the particles of iron aggregate to some extent, and, 



REDUCED IRON. 163 

when cold, are only slowly oxidized in dry air. This latter form 
of reduced iron is Fer reduit, or Quevenne's Iron, the Ferripulvi.^-, 
or Ferrum Reductum, U. S. P. — "a very fine grayish-black lustre- 
less powder, without odor or taste. " It is often administered 
in the form of a lozenge, gum and sugar protecting the iron from 
oxidation as well as forming a vehicle for its administration. 

Note. 1 — The spontaneous ignition of the iron in the above 
experiment is an illustration of the influence of minute division on 
the occurrence of chemical change. The action is the same as 
that which occurs when iron wire burns (as it does with great 
brilliancy) in oxygen. The surface exposed to the action of the 
oxygen of the air is, in the case of this variety of reduced iron, so 
enormous compared with the weight of the iron, that the heat is 
not conducted away sufficiently fast to prevent elevation of tem- 
perature to a point at which the whole becomes incandescent. 
The mixture of lead and carbon (lead pyrophorus) resulting when 
lead tartrate is carefully heated in a test-tube until fumes cease to 
be evolved, spontaneously ignites when thrown into the air, and 
for the same reason. Many substances, solid and liquid, if liable 
to oxidation, and sufficiently finely divided, and especially if ex- 
posed in a warm place, become hot and even occasionally burst 
into flame spontaneously. Oil on cotton waste, powdered char- 
coal, coal (especially if pyritic, porous, or powdered), resins in 
powder, and even flour and hay, are familiar illustrations of 
materials liable to ''heat," or char, or even burn spontaneously. 

Note 2. — The student who has time and opportunity to do so, 
is advised to carry out experiment 16, as a roughly quantitative 
one, by way of realizing what has already been stated (see Laivs 
of Chemical Combination, pp. 51, 52), with respect to chemical 
actions, that they take place between definite weights only of 
matter. Three tubes, similar to the oxide tube shown in Fig. 32 
(or three U tubes), should be prepared, the second being con- 
nected to the first, and the third to the second, in the usual man- 
ner, by means of India-rubber tubing. The first tube should con- 
tain pieces of calcium chloride to absorb any traces of moisture 
not retained by the sulphuric acid. The second tube (the ends 
of the small tube being temporarily closed by small corks) should 
be weighed in a balance which will turn with a quarter of or half 
a grain, and, the weight having been noted, 159 grains of^dry 
ferric oxide should be neatly placed in the middle of the tube. 
(The oxide, before being weighed must be heated in a small 
crucible over a Bunsen flame to convert any ferric oxyhydroxide 
into ferric oxide, and to remove all traces of moisture). The third 
tube should contain pieces of calcium chloride to absorb the water 
produced in the reaction, and should be weighed just before being 
connected. The operation is now carried out. At its close, and 
when the middle tube is cold, the latter and the third tube are. 
again weighed. The oxide tube should weigh nearly 48 (47. (.il) 



164 THE METALLIC RADICALS. 

grains less than before, and the calcium chloride tube nearly 54 
(53, 64) grains more than before. 

FeA + 3H., = 2Fe + 3H,0 
(111 + 47.64)- 6 = 111 + 53.64 

The operation is completed more quickly if one-half or one-fourth 
of the weight of the oxide being taken; in that case one-half or 
one-fourtlTof the weights of iron and of water will be obtained. 
Indeed any weight of oxide may be employed; the amount of iron 
and water resulting will be always exactly proportionate to the 
weights just mentioned, provided the whole of the ferric oxides 
is reduced to iron. 

Analytical Reactions of Iron Salts. 
Reactions of Ferrous Salts. 

1. Pass hydrogen sulphide, H.,S, through a solution of a 
ferrous salt \e.g., ferrous sulphate) slightly acidulated with 
hydrochloric acid ; no precipitate is produced. This is a 
valuable negative fact, as will be evident presently. 

2. Add ammonium hydrosulpbide, NH^SH, to solution of 
a ferrous salt; a black precipitate of ferrous sulphide, FeS, 
is produced. 

FeSO, + 2]S'H,SH = FeS + (XHJ,,SO, + H,S 

3. Add solution of potassium ferrocyanide (yellow prus- 
siate of potash), K_^FeCgXg, to a solution of a ferrous salt ; a 
pale blue precipitate is produced, which rapidly becomes 
darker blue owing to absorption of oxygen and conversion 
into Prussian blue. (^See p. 165.) 

4. To a solution of a ferrous salt add potassium ferricyan- 
ide (red prussiate of potash) RgFeCgN^; a dark blue precipi- 
tate is produced of Turnbull's blue, resembling Prussian blue.^ 

Other Analytical Reactions. — The precipitates produced 
from ferrous solutions on the addition of alkali-metal carbon- 
ates, phosphates, and arsenates as already described in the 
experiments dealing with the preparation of the corresponding 
ferrous salts, are characteristic, and hence have a certain 
amount of analytical interest, but are inferior in this respect 
to the four reactions above mentioned. 

' Cyanogen (CN'. or Cy'), ferrocyanogen (FeCfiXfi"", or FeCye'^") and 
fcrricyanogen (FeCfiXe"'. or FeCye"') are radicals which play the part of 
non-metallic elen)ents. just as ammonium in its chemical relations resem- 
bles the metallic elements. They will be referred to again. 



FERROUS SALTS. 165 

Note. — Solution of ammonia, and solutions of caustic potash 
and soda in presence of ammonium salts, are incomplete precipi- 
tants of ferrous salts. To a solution of a ferrous salt add ammo- 
nia; on filtering oft' the whitish ferrous hydroxide, and testing the 
filtrate with ammonium hydrosulphide, iron will still be found 
in solution. To another portion of the ferrous solution add a few 
drops of nitric acid, or excess of chlorine water, and boil; this 
converts the ferrous into ferric salt, and alkalies, including ammo- 
nia, will now precipitate the iron completely as ferric hydroxide. 

In actual analysis, the separation of iron as ferric hydroxide is 
an operation of frequent performances. This is always accomp- 
lished by the addition of alkali after (if the iron occurs as a fer- 
rous salt) previous ebullition with a little nitric acid. Potassium 
ferrocyanide and ferricyanide are the reagents most commonly used 
in distinguishing ferrous from ferric salts. 

Reactions of Ferric Salts. 

1. Through a solution of a ferric salt (e.^., ferric chloride) 
pass hydrogen sulphide; a white precipitate of sulphur (from 
the hydrogen sulphide), is produced. The ferric salt is 
simultaneously converted into a ferrous salt, the latter remain- 
ing in solution. This reaction is of frequent occurrence in 
analysis :— 2FeCl3 -{- H.,S = 2FeCl, + 2HC1 + S. 

2. Add ammonium hydrosulphide to a solution of a ferric 
salt ; the latter is reduced to the ferrous state, and a black 
substance (ferrous sulphide, FeS) is precipitated as in the 
second analytical reaction of ferrous salts, sulphur being set free. 

3. To a solution of a ferric salt add potassium ferrocyanide, 
K^FeCgNg; a precipitate of Prussian blue (the well-known 
pigment), is produced. 

4. To a solution of a ferric salt add potassium ferricyanide ; 
no precipitate is produced, but the liquid assumes a dark 
brownish red color (or a greenish olive hue if the salts are 
not quite pure). 

5. Add sodium hydroxide or ammonia water to a solution 
of a ferric salt; a reddish-brown precipitate of ferric hydrox- 
ide, Fe(OH)^, is produced (compare experiment 11, p. 157). 

Other Analytical Reactions. — Some of these have occasional 
interest. In neutral ferric solutions the tannic acid in aqueous 
infusion of galls occasions a bluish-black inky precipitate, 
the basis of most black writing inks. — Potassium thiocyanate, 
KSCN, causes the formation of ferric thiocyanate, which is 
of a deep blood-red color. The color disappears on the addi- 
tion of mercuric chloride. 



166 THE METALLIC RADICALS. 

There is no normal ferric carbonate; alkali-metal carbon- 
ates cause the precipitation of ferric hydroxycarbonate while 
carbonic anhydride escapes. 



QUESTIONS AND EXEECISES. 



Name the chief ores of iron. — How is the metal obtained from the ores? 
— What is the chemical difference between cast-iron, wrought-iron, and 
steel ? — Explain the process of "welding." — What is the nature of chal^^- 
beate waters? — Illustrate by formulae the difference between ferrous and 
ferric salts. — Write a paragraph on the nomenclature of iron salts. — Give a 
diagram of the process for the prepai-ation of ferrous sulphate. — In what 
respects do the official Ferrous Sulphate and Exsiccated Ferrous Sulphate 
differ?— How is ferrous sulphate obtained on the large scale ?— Give the 
chemical names of white, green and blue vitriols. — Why does ferrous sul- 
phate become brown on exposure to air ?— Eepresent by an equation the 
formation of Ferrous Carbonate. — Describe the action of atmospheric oxy- 
gen on ferrous carbonate; can the effect be prevented ?— In what order 
would you mix the ingredients of Mistura Ferri Composita, and why? — 
Name four iron compounds which may be formed by the direct union of 
their elements. — Give the official method for the preparation of Solution 
of Ferric Chloride. — How may Ferrous be converted into Ferric Sulphate ? 
— What is the formula of Ferric Acetate, and how is it prepared ? — How 
does Ferric Hydroxide act as an antidote in arsenical poisoning? — What 
are the properties of ferric oxide? — What are the general characters and 
mode of production of the medicinal scale preparations of iron? — Give a 
diagram showing the formation of Ferric Nitrate.— Calculate how much 
ferric oxide will yield, theoretically, one hundredweight of iron. Ans. 
160 lbs., approximately. — Describe the action of each of the following re- 
agents on solutions of iron salts, distinguishing between ferrous and ferric 
reactions, and illustrating each of the reactions by an equation : — a. Am- 
monium hydrosulphide. b. Potassium ferrocyanide. c. Potassium ferri- 
cyanide. d. Caustic Alkalies, e. Potassium thiocyanate. — Describe the 
action of ammonia water on salts of iron, aluminium and zinc respec- 
tively. 



CHROMIUM: Cr. Atomic weight, 51.7. 

Occurence. — The chief ore of chromium is chrome ironstone, 
FeO, Cr203, chromife, occurring chiefly in the United States and 
in Sweden. The metal may be isolated by the action of alumi- 
nium on chromic oxide, CrgOg, at a very high temperature. 

Chromium forms sets of salts corresponding to chromous and 
chromic oxides, CrO and CrgO, respectively, but the chromous 
salts are exceedingly readily converted by processes of oxidation 
into chromic salts, and can only be prepared and preserved with 
difficulty. The ordinary salts in which chromium plays the part 
of the metallic radical, are the chromic salts, such as chromic 
chloride, CrClj ; chromic sulphate, CrjSOJa ; etc. Chromium 
also forms an acid anhydride, chromic anhydride, CrO.^, and the 
best known chromium compounds — the chromates (e.^., potassium 



CHROMIUM. 167 

chromate, K2CrOJ, and the dichromates or anhydrochromates 
{e.g., potassium dichromate, K.^CrO^^, CrOa or K^CrgO^) in which 
the chromium forms a part of the complex acid radicals CrO/^ 
and Cr^O/^ — are referred to the unknown chromic acid [H.^CrO^] 
and anhydrochromic acid [HaCr.^OJ, corresponding to this anhy- 
dride. Most of the commoner chromium compounds are obtained 
from potassium dichromate. 

Preparation of Potassium Bichromate. — On roasting powdered 
chrome iron ore with potassium carbonate and nitrate, yellow 
potassium chromate, K2CrO^, is obtained; the mass, treated with 
acid, yields red potassium dichromate, K^Cr04, CrOg, or K^Cr20^ 
{Potassii Dichromas, U. S. P.).: — 

2K2CrO, + 2HC1 = K^Cr^r + 2KC1 + Kfl 

From this, other chromates are prepared, and, by reduction, as 
presently explained, the chromic salts. 

Heated strongly in a crucible, potassium dichromate splits up into 
potassium chromate, glistening green chromic oxide, and oxygen, 
4K2Cr20- = 4K2Cr04 + 2Cr,03 + 30,. Ammonium dichromate, 
when heated yields several times its volume of bluish-green chromic 
oxide, water, and nitrogen. (NH4)2Cr20^ = ^^2^'i + 4H2O + 'N.^. 
The yellow and orange lead chromates (lead chromate PbCrO^, and 
basic lead chromate, Pb20Cr04), are used as pigments. 

Potassium Chromate. — The normal or yellow potassium chromate 
is obtained on adding potassium bicarbonate, 200 grains, in small 
quantities at a time, to a hot solution of the dichromate, about 
295 grains, until effervescence ceases. 

K^Crp, + 2KHCO3 = 2K2CrO, + 200^ + H.p 

For analytical purposes solution of a normal chromate is still 
more readily prepared by simply adding ammonia water to a 
solution of potassium dichromate, until the liquid turns yellow 
and, after stirring, smells of ammonia. 

K^Cr^O, + 2NHpH = K^CrO, + (NHJ^CrO, + H.p 

Conversion of a chromate {in lohieh chromium, forms part of 
an acid radical) into a chromic salt (in wliicli chromium is the 
metallic radical). — Through an acidulated solution of potassium 
dichromate pass hydrogen sulphide : sulphur is deposited, and 
a green chromic salt remains in solution — chromic chloride, 
CrClg, if hydrochloric acid be used, and sulphate, Cr._,(SO^).,, 
if sulphuric be the acid employed. Boil the liquid to expel 
excess of hydrogen sulphide, filter, and reserve the solution 
for subsequent experiments. (For an equation representing 
this reaction, see p. 168). Alcohol, sugar, and various other 



168 THE METALLIC RADICALS. 

substances which are moderately easily oxidized answer as 
well as hydrogen sulphide. For a method of carrying out 
the reverse operation to that just described, i. e., the conver- 
sion of a chromic salt into a chromate, see the dry-way 
reaction for chromium compounds in general on p. 170. 

Chromic sulphate, Cr^(S0j3, like aluminium sulphate, Al2(S04)3, 
unites with alkali-metal sulphates to form double salts which are 
called alums. These alums resemble common alum in crystalline 
form; but they do not contain aluminium, the place of the latter 
being taken by chromium: they are of a purple color. 

Chromic Anhydride. 

Experiment. — Mix four volumes of a cold saturated aqueous 
solution of potassium dichromate with five of sulphuric acid ; 
on cooling, chromic aiiliydride often called chromic acid, CrOg, 
(Chromii Trioxidum, U. S. P.), separates in crimson needles. 
After well draining, the crystals may be freed from adhering 
sulphuric acid by washing once or twice with nitric acid : the 
latter may be removed by passing dried and slightly warmed 
air through a tube containing the crystals. Chromic anhy- 
dride may also be freed from sulphuric acid by one or two 
recrystallizations. In contact with moisture, chromic anhy- 
dride takes up water and forms a solution of anhydrochromic 
acid [H^Cr.^0.]. Chromic anhydride is a powerfully corrosive 
oxidizing agent; it melts between 356° and 374° F. (180° to 
190° C), and at a higher temperature decomposes, yielding 
chromic oxide and oxygen; it oxidizes organic matter with 
great violence, spontaneous ignition sometimes resulting. 

In the systematic analytical examination of solutions contain- 
ing chromates, the chromium is preci])itated as green chromic 
hydroxide along with ferric and aluminium hydroxides, the prior 
treatment with hydrogen sulphide in presence of hydrochloric 
acid reducing the chromate to the condition of a chromic salt, 
thus: — 

2K2Cr20, + 16HC1 + 6H,S = 4CrCl3 + 4KC1 f 14H,0 -^ 38^ 

Chromium having been found in a solution, its condition as chro- 
mate may be ascertained by noting the yellow or orange color of 
the solution; by observing the precipitation of sulphur, as above, 
with simultaneous change in color from orange to green when the 
acidulated solution is treated with excess of hydrogen sulphide; 
and by applying to the sohition, salts of barium, mercury, lead, 
and silver. (See the various paragraphs relating to those metals). 



CHROMIUM. 169 

Ba(N03)^ gives yellow BaCrO^ with cliromates. 

H2:N0.. ,, red Hg^CrO, 

AgNOj ,, red Ag.^CrO, 

AgNO;^ ^^ red Ag2Cr,0^ with diehromates. 

Pb(C2H302)2 ,, yellow PbCrO^ wdth both. 

Barium nitrate does not completely precipitate diehromates, 
barium dichromate being soluble in water ; barium chromate is 
insoluble in water and in acetic acid, but soluble in hydrochloric 
or nitric acid. Mercurous nitrate does not wholly precipitate 
diehromates : mercuric nitrate or chloride only partially precipi- 
tates chromates, and does not precipitate diehromates. Mercurous 
chromate is insoluble, or nearly so, in dilute nitric acid. Silver 
chromate and dichromate are soluble in acids and alkalies. Lead 
acetate precipitates lead chromate from both chromates and di- 
ehromates, acetic acid being set free in the latter case (K2Cr20^H- 
2Vh{C.,K.Jd^\ + H^ - 2PbCrO, + ^KC^H^O^ + 211Clll,0;). 

A delicate reaction for dry chromates depends on the 
formation of ehromyl chloride or chlorocliromic anhydride, 
Cr02Cl2. A small portion of the chromate is placed in a test- 
tube with a fragment of dry sodium chloride and a drop or 
two of sulphuric acid, and the mixture is heated ; red irrita- 
ting fumes of chlorocliromic anhydride are evolved, and con- 
dense in dark red drops on the side of the tube. 

Larger quantities are obtained by the same reaction, the opera- 
tion being conducted in a retort, with thoroughly dry materials, 
as the compound is decomposed by w^ater. Chlorochromic anhy- 
dride may be regarded as chromic anhydride in which an atom of 
oxygen is displaced by an equivalent quantity (two atoms) of 
chlorine. It is not used in medicine, but is of interest to the 
student as an example of a class of compounds known as aci- 
chlorides. The reaction is also occasionally serviceable for the 
detection of chlorides. 

Analytical Reactions of Chromic Salts. 

1. To a solution of a chromic salt (chloride, sulphate or 
chrome alum) add ammonium hydrosulphide ; a bulky green 
precipitate of chromic hydroxide, Cr(0H)3, is produced. 

CrCla + 3NH,SH + 3H,,0 = Gr(0H)3 + 3NH,C1 + 8H.S 

2. To a solution of a chromic salt, add anunonia water ; 
green chromic hydroxide is precipitated, insoluble in excess. 

3. To a solution of a chromic salt, add solution of sodium 
or potassium hydroxide drop by drop; green chromic hy- 
droxide is precipitated. Add excess of the alkali ; the \n'c- 



170 THE METALLIC RADICALS. 

cipitate is dissolved. Boil the solution for some time ; chro- 
mic hydroxide is reprecipitated. 

Chromic Oxyhydroxides. — Intermediate in composition between 
chromic hydroxide, Cr(0H)3, and chromic oxide, Cr.^0;^, two oxy- 
hydroxides are known, namely, Cr^O(OH)^ and CrOOH. 

Dry- way Reaction for Chromium Compounds in general. — 

Mix a small quantity of any chromium compound with sodium 
carbonate and a few grains of nitre on platinum foil, and fuse 
the mixture in the blow pipe-flame ; a yellow^ mass (potassium 
and sodium chromates) is formed. Dissolve the mass in 
water, add acetic acid to decompose excess of carbonate, and 
apply the reagents for chromates. This is a delicate and use- 
ful reaction if carefully performed. 

The production of the chromate from a chromic salt in the 
above reaction may be represented by the equation : — 

2CrCl3 + SNa^COg + 30 = SNa^CrO, + 6XaCl + 500^. 



DIRECTIONS FOR APPLYING THE ANALYTICAL REACTIONS DE- 
SCRIBED IN THE FOREGOING PARAGRAPHS TO THE ANALYSIS 
OF AN AQUEOUS SOLUTION OF SALTS CONTAINING ONE OF 
THE METALS, ALUMINIUM, IRON, CHROMIUM. ^ 

First note the color of the solution : — 

Solutions of aluminium salts are colorless. 

Solutions of ferrous salts are colorless or pale green. 

Solutions of ferric salts are yellow or brownish. 

Solutions of chromic salts are bluish-purple or green. 
Add ammonia water (the group reagent) gradually : — 

A white precipitate, insoluble or nearly so in excess, indi- 
cates an aluminium salt. 

A dirty-green precipitate indicates iron in the state of a 
ferrous salt. 

A reddish-brown precipitate indicates iron in the state of a 
ferric salt. 

^ The analytical behavior of chromium in the chromic salts is alone re- 
ferred to here. In the systematic examination of solutions for other 
metallic radicals besides those hitherto considered, any chromate or 
dichromate originally present is converted into chromic salt before the 
stsise is reached at which aluminium, iron, and chromium are tested for. 
(Note, however, that solutions of chromates and dichromates are yellow 
and orange respectively. 



UA LIT A TI VE ANA L YSIS. 



171 



A bluish-grey precipitate, insoluble or nearly so in excess, 
indicates a chromic salt. 

These results may be confirmed by the application of some 
of the other tests to fresh portions of the solution. 

TABLE OF SHORT DIRECTIONS FOR APPLYING THE ANALYTICAL 
REACTIONS DESCRIBED IN THE FOREGOING PARAGRAPHS TO 
THE ANALYSIS OF AN AQUEOUS SOLUTION OF SALTS OF ONE, 
TWO, OR ALL THREE OF THE METALS, ALUMINIUM, IRON, 
CHROMIUM. 

Boil about one-third of a test-tubeful of the solution with a 
few drops of nitric acid. This ensures the conversion of ferrous 
into ferric salt, and enables the next reagent (ammonia) com- 
pletely to precipitate the iron. Add a slight excess of ammo- 
nia water and shake the mixture ; filter. Wash the precipi- 
tate, dry it, and fuse it on platinum foil with sodium carbonate 
and potassium nitrate. Boil the fused mass in water, and filter. 



Residue. 
FePs 
brown 

{Note 1) 



Filtrate. 

If yellow, Cr is present and has formed chromate 
during the fusion. Divide into two parts. 



Add NH4CI and 
warm. White ppt. in- 
dicates Al. 



Add acetic acid in excess 
and AgNOg. Eed ppt. in- 
dicates Cr. 



Note 1. — If iron is present, portions of the original solution 
must be tested with potassium ferricyanide for ferrous, and with 
potassium ferrocyanide for ferric salts; dark-blue precipitates indi- 
cate ferrous and ferric salts respectively. 

Note 2. — If ferrous salt is not present, the preliminary ebul- 
lition with nitric acid is unnecessary. It is perhaps therefore 
advisable always to determine this point previoudi/ by testing a 
little of the original solution with potassium ferricyanide ; if no 
blue precipitate is produced, the nitric acid treatment may be 
omitted. 

Cerium: Ce. At. wt., 139.2. — This element occurs in the 
mineral cerite (which contains iron, calcium, and the rare metals, 
cerium, lanthanum, and didymium [the latter really a mixture of 
neodymium and praseodymium] as silicates); also occasionally 
as impure fluoride, carbonate, and phosphate. The oxalate, Cerii 



■■ 



172 THE METALLIC RADICALS. 

Oxnlas, U. S. P., a white granular powder, is the only official 
salt ; it may be obtained from cerite by boiling the powdered 
mineral in concentrated hydrochloric acid for several hours, evap- 
orating, diluting and filtering to separate silica; adding ammo- 
nia water to precipitate hydroxides of all the metals except cal- 
cium; filtering, Avashing, redissolving in hydrochloric acid, and 
adding oxalic acid to precipitate cerium oxalate. The prepara- 
tion still contains lanthanum and didymium oxalates ; it is there- 
fore strongly calcined, the resulting lanthanum and didymium 
oxides dissolved out to some extent by boiling with a concentrated 
solution of ammonium chloride, the residual cerium oxide dis- 
solved in boiling hydrochloric acid, and ammonium oxalate added 
to precipitate cerium oxalate, 0^,(0^0^).,, 9H2O. According to 
Hartley, the precipitated hydroxides should be treated with 
chlorine, by Avhich eerie hydroxide is left insoluble and the other 
hydroxides converted into soluble hypochlorites. 

The oxalate is insoluble in Avater. It is decomposed at a dull- 
red heat, 47 percent, of a yellow or, generally, salmon-colored 
mixture of oxides remaining. Usually the didymium present gives 
the ignited residue a reddish or reddish-brown color. The oxides 
are soluble in boiling hydrochloric acid (without efiervescence, in- 
dicating, indirectly, absence of earthly and other carbonates or 
oxalates) ; and the solution gives, wdth excess of a saturated solu- 
tion of potassium sulphate, a crystalline precipitate of double 
cerium and potassium sulphate. Aluminia mixed with cerium 
oxalate may be detected by boiling with solution of potassium 
hydroxide, filtering, and adding excess of solution of ammonium 
chloride, when a white flocculent precipitate (aluminium hydrox- 
ide) will be obtained. The oxalic radical is recognized by neutral- 
izing the potassium hydroxide solution with acetic acid, and add- 
ing calcium chloride; a white precipitate (calcium oxalate) falls : 
this precipitate, though insoluble in acetic acid, should be wholly 
soluble in hydrochloric acid. Acid or neutral cerium solutions 
give with sodium acetate and hydrogen peroxide a brownish-red 
color (Hartley). 

QUESTIONS AND EXERCISES. 

State the method of preparation of potassium dichromate. — Give the 
formnlse of potassium chromate and dichromate. — How is potassium chro- 
mate obtained? — Describe the action of hj'drogen sulphide on acidulated 
solutions of chromates. — What is the formula of chrome alum? — Mention 
the chief tests for chromates and for chromic salts. — What are the formula 
and properties of cerium oxalate ? 

ARSENIC and ANTIMONY. 

These elements, especially antimony, resemble metals in ap- 
pearance and in the character of some of their compounds; but 
they are still more closely allied to the non-metals phosphorus 



ARSENIC AND ANTIMONY. 173 

and nitrogen, with which they form a natural group. The hydro- 
gen compounds of the four members of this group are represented 
by the formulae NH3, PH3, AsHg, SbHs. A few preparations of 
arsenic and antimony are used in medicine; but all are more or 
less powerful poisons, and hence have toxicological interest. 

From observations of the vapor density of arsenic, it would 
appear that the molecule of arsenic contains four atoms, and that 
its formula is As^. At temperatures above 1700° C the vapor 
density corresponds to the formula AS2. 

From observed analogy between the two elements, the molecu- 
lar constitution of antimony is probably similar to that of arsenic. 
Vapor density determinations, moreover, lead to the formulae 
As^g and Sb^Og for arsenous and antimonous oxides (the formula 
AS2O3 has been adopted in the U. S. P.). 

ARSENIC: As. Atomic weight, 74.4. 

Occurrence, etc. — Arsenical ores are frequently met with in 
nature, the commonest being iron arseno-sulphide, FeAsS. This 
''mispickel" is roasted in a current of air, the oxygen of which, 
combining with the arsenic, forms common white arsenic[ ' 'arsenic") 
or arsenic trioxide, sometimes called anhydrous arsenous acid, or 
better, arsenous anhydride, As^Of., [Arserd Trioxidum, U. S. P.), 
which is condensed in chambers or long flues. It commonly 
occurs as a heavy, white, opaque powder, or in masses which 
usually present a stratified appearence caused by the presence, in 
separate layers, of the crystalline and opaque and of the amor- 
phous and vitreous allotropic modifications. The vitreous or amor- 
phous oxide is far more soluble than the crystalline variety, and 
the two kinds exhibit other differences in properties. Such dif- | 

ferences between the crystalline and amorphous varieties of an 
element or compound or between two crystalline varieties are not 
infrequent. Realgar (red algar) is native red arsenic sulphide, 
AS2S2, and orpiment {auripigynentum, the golden pigment), is 
native yellow sulphide, As2S.^. Arsenous iodide, Aslg, (Arseni 
lodidum, U. S. P.), may be made from its elements or by dissolv- 
ing white arsenic in aqueous hydriodic acid and evaporating the 
solution. It occurs in small orange-colored crystals, or crystal- 
line masses, soluble with partial decomposition in water and in 
alcohol. Its aqueous solution affords the reactions characteristic 
of arsenic and of iodides, and is neutral to litmus. Heated in a 
test-tube, it almost entirely volatilizes, violet vapors of iodine 
bsing set free. Ebullition with much water gives rise to the 
formation of a basic salt. A solution of 1 part by weight of 
arsenous iodide and 1 part by weight of mercuric iodide in 100 
fluid parts of water, forms LiqnQg^Kjb^ni et Hydrargyri lodidi, 
U. S. p. {Dovonan^ s Sohdion). ^^^K^\ 



174 THE METALLIC RADICALS. 

Alkaline Solution of Arsenic. 

Experiment 1. — Boil a grain or two of powdered white 
arsenic, As^Og, in a solution of potassium bicarbonate and filter 
if necessary. The solution, colored with compound tincture 
of lavender, and containing 1 part by weight of As^O^ in 100 
fluid parts, forms Liquor Potassii Arsenitis U. S. P. {Fowler's 
Solution). 

Arsenous Acid and other Arsenites. 

AVhite arsenic, or arsenous anhydride, As^Og (formerly called 
arsenous acid), when dissolved in water yields a solution which 
contains some arsenous acid, H3ASO3, hydrogen arsenite, and 
possesses a faintly acid reaction. 

As.Og + 6H,0 = 4H3AsO;^ 

Arsenous anhydride Water Arsenous acid 

When arsenous anhydride is dissolved in sokitions of potassium 
or sodium hydroxide, the anhydride being used in excess, the so- 
called acid arsenites, KH(As02)2 and NaH(As02)2, are formed. 
Boiled for some time with excess of the respective alkali-metal 
carbonates, these salts yield other arsenites (really metaresenites, 
as the acid salts also are) the composition of which is represented 
by the formulae KAsOg and NaAsOg. 

Arsenous anhydride fused with alkali-metal carbonates yields 
pyroarsenates (Na^As207 or K^As20p as the case may be) and 
metallic arsenic. 

Acid Solution of Arsenic. 

Experiment 2. — Boil arsenous anhydride with dilute hydro- 
chloric acid; the anhydride slowly dissolves. Such a solution 
made with prescribed proportions of acid and water, and con- 
taining 1 part by weight of As^Og in 100 fluid parts, forms 
Liquor Acidi Arsenisi U. S. P. {De Valarigin's Solution con- 
tains a grain and a half per ounce. ) 

Note. — The student should also boil arsenous anhydride in 
water only, and thus have an acid, an alkaline, and an aqueous 
arsenous solution for analytical comparison. 

Arsenic. 

Experiment 3. — Place a grain or less of arsenous anhy- 
dride at the bottom of a narrow test-tube, cover it with half 
an inch or so of small fragments of dry charcoal, and hold 
the tube, nearly horizontally, in a Bunsen flame, the mouth 



ARSENIC. 175 

of the tube being loosely covered by the thumb. At first let 
the bottom of the tube project slightly beyond the flame, so 
that the charcoal may become nearly red-hot; then heat the 
bottom of the tube. The oxide will volatilize, become deoxi- 
dized by the hot charcoal, carbonic anhydride being formed, 
and the element arsenic (formerly sometimes termed arseni- 
cum), will be deposited in the cooler part of the tube as a dark 
mirror-like metallic coating. During the operation a charac- 
teristic odor, resembling garlic, is emitted. 

Metallic arsenic may be obtained in large quantities by the above 
process if the operation be conducted in vessels of appropriate 
size. Performed on the small scale with great care, in narrow 
tubes, and using not charcoal alone, but black fiux (a mixture of char- 
coal and potassium carbonate obtained by heating acid potassium 
tartrate in a test-tube or other closed vessel till no more fumes 
are evolved), the reaction has considerable analytical interest, the 
garlic odor and the formation of the mirror-like ring being highly 
characteristic of arsenic. Compounds of mercury and antimony, 
however, give sublimates which resemble arsenic in appearance 
and must not be mistaken for it. 



Arsenic Acid and other Arsenates. 



} 
I 
Experiment 4. — Boil a grain or two of arsenous anhydride ). \ 

with a few drops of nitric acid until red fumes are no longer 
evolved; evaporate the solution to dryness in a small dish, 
to remove excess of nitric acid ; dissolve the residue in water : 
the product is Arsenic Acid, HgAsO^. 

Arsenic acid, when strongly heated, loses the elements of water, 
and arsenic anhydride, AS2O5, remains. At a still higher tempera- 
ture arsenic anhydride decomposes, yielding arsenous anhydride 
and oxygen. 

Arsenic anhydride- readily absorbs water and becomes arsenic 
acid, HgAsO^. Arsenic acid is reduced to arsenous acid by the 
action of sulphurous acid. H3As04+H2S03=H3As034-H2S04. 

Salts derived from arsenic acid are termed arsenates. The 
di-ammonium arsenate, (NH^)2H^sC)4,may be made by neutrali- 
zing arsenic acid with ammonia. Its solution in water is occasion- 
ally used at a reagent in analysis. Arsenic acid is used as an 
oxidizing agent in the manufticture of the well-known dye, 
magenta. 

Sodium arsenite and arsenate are used in the cleansing opera- 
tions of the calico-printer. 



176 THE METALLIC RADICALS. 

Sodium Arsenate and Pyroarsenate. 

Experiment 5. — Fuse 2 or 3 grains of arsenous auhydride, 
As^O^, with sodium nitrate, NaNO^, and dried sodium carbon- 
ate, Na^COg, in a porcelain crucible, and dissolve the result- 
ing mass of sodium pyroarsenate in water; solution of sodium 
arsenate, Na^HAsO^ results. 

Asp,+4NaN03-L2Na,C03 = 2Na,As.p^-L2NP3-L2CO, 

Arsenous Sodium Sod'ium Sodium Nitrous Carbonic 

anhydride nitrate carbonate pyroarsenate anhydride anhydride 

Na^AsP, + HP = 2Xa.3HAsO, 

Sodium pyroarsenate Water Sodium arsenate 

Crystallized from the solution and dried, a salt is obtained which is 
represented bv the formula NagHAsO^, THgO. [Sodii Arsenas, 
U. S. P.) 

The anhydrous salt, Xa^HAsO^, obtained by exposing to a tem- 
perature of 302° F. (150° C), crystallized sodium arsenate, is 
official {Sodii Arsenas Exsiccatus, U. S. P. ). A 1 percent, 
aqueous solution forms Liquor Sodii Arsenatis, U. S. P. It has 
about half the arsenical strength of Liquor Potassii Arsenitis, 
U. S. P. The anhydrous salt is used because the crystallized salt 
is of somewhat uncertain composition. The fresh crystals are 
represented by the formula Xa.2HAs04, 12H.^0 (=53.7 percent, 
of water) : these soon effloresce and yield a stable salt having the 
formula Na^HAsO^, TH^O (= 40.4 percent, of water). To avoid 
the possible employment of a mixture of these salts, the anhydrous 
salt, of uniform composition, is alone official. 

The student will find useful practice in verifying, by calculation, the 
above numbers representing the centesimal proportion of water in the 
two sodium arsenates. 

The crvstalline form of each varietv of sodium arsenate 
(Na,HAsd„ I2H2O, and Na,HAsO„ TH^O) is identical with that 
of the corresponding sodium phosphate (Xa.^HPO^, I2H2O, and 
Xa-^HPO^, 7H2O), the pairs of analogous composition being iso- 
morphous. This is only one instance of the strong analogy of 
arsenic and its compounds with phosphorous and its correspond- 
ing compounds. The preparations and characters of the next 
substance, ferrous arsenate, will remind the student of ferrous 
phosphate. 

Ferrous Arsenate. Iron Arsenate. 

Experiment 6. — To a hot solution of sodium arsenate add 
a hot solution of ferrous sulphate and a small quantity of a 
solution of sodium bicarbonate ; a precipitate of ferrous arsen- 
ate, Fe^fAsOJg' i* produced. On a larger scale, 26- parts 



ARSENIC. 



Ill 



of dried sodium arsenate dissolved in 100 of hot water, and 
20f of ferrous in 120 of hot water, with 4 J of sodium bicar- 
bonate, may be employed. The precipitate should be col- 
lected on a calico filter, washed, squeezed, and dried on a 
water-bath, at a low temperature (100° F., 37.8° C.) to avoid 
excessive oxidation. It is ferrous arsenate, Fe3(AsO^)^, GH^O, 
with ferric arsenate and some iron oxide. 



2Na^HAsO, 

Sodium arsenate 

Fe/AsO.), + 

Ferrous arsenate 



2]SraHC03 

Sodium bicarbonate 



3Na,S0, 

Sodium sulphate 



h 3FeS0, = 

Ferrous sulpliate 

2Hp + 2C0, 

Water Carbonic anhydride 



The use of the sodium bicarbonate is to ensure the absence of 
free sulphuric acid from the solution. This acid dissolves ferrous 
arsenate, and it is impossible to prevent its liberation if only the 
ferrous sulphate and sodium arsenate be employed without the 
sodium bicarbonate. 

At the instant of precipitation ferrous arsenate is white, but it 
rapidly becomes of a green or greenish-blue color owing to absorp- 
tion of oxygen and formation of a ferrosoferric arsenate. When 
dry, it is a tasteless, amorphous powder which is soluble in acids 
and has undergone oxidation to a considerable extent. 

Arsenic Hydride and Sulphides, and Copper and Silver Arsenites 
and Arsenates are mentioned in the following analytical paragraphs. 

Analytieal Reactions of Arsenic Compotmds. 

1. Repeat experiment 3, operating on not very much more 
arsenous anhydride than the size of a small pin's head, and 
using not charcoal alone, but the black flux already mentioned, 
or a well-made and perfectly dry mixture of charcoal and 

Fig. 33. 




potassium carbonate (the latter salt best obtained by heating 
potassium bicarbonate). The tube employed should he a 
narrow test-tube, or better, a tube (easily made from glass- 
tubing) having the form (Berzelius's) shown in Fig. 33. 

The oxide and black flux are placed in the bulb of the 
tube, which is then heated in a Bunsen flame; the arsenic 
condenses on the constricted portion of the tube. If now the 
bulb be carefully removed by fusing and drawing out the 
glass, the arsenic may be chased up and down the narrower 
12 



178 



THE METALLIC RADICALS. 



part of the tube until the air in the tube has re-oxidized it to 
arseuous anhydride. 

If the operation has been performed in a less delicate man- 
ner in an ordinary test-tube, cut or break off portions of the 
tube containing the sublimate of arsenic, put them into a test- 
tube and heat the bottom of the latter, holding it nearly hori- 
zontally, and partially closing the mouth of the tube with the 
finger or thumb; the arsenic combines with oxygen from the 
air in the tube, and the resulting arsenous anhydride is 
deposited on the cool part of the tube in brilliant, generally 
imperfect, octahedral crystals. 

Fig. 34a. 



Fig. 34 





Octahedron. 



A sublimate of arsenous anhy- 
dride (Magnified). 



Microscopic Examination. — Prove that the crystals are 
identical in form with those of arsenous anhydride, by heating 
a grain or less of the latter in another test-tube and examin- 
ing the two sublimates by means of a good lens or a compound 
microscope. 

The appearance of a sublimate of arsenous anhydride is 
peculiar and quite characteristic. The primary form of each 
crystal is an octahedron {oktu^ oMo, eight; f'V^", hedra, side) 
(Fig. 34a), or, rarely, a tetrahedron, and in a sublimate a 
few perfect octahedra are generally present. Usually, how- 
ever, the crystals are modifications of octahedra such as are 
shown in Fig. 34 — which is drawn from actual sublimates. 

2. Reinsch's Test. — Place a piece of copper foil, about i 
inch wide and i inch long, in a solution containing arsenic 
and hydrochloric acid, and boil (nitric acid must not be 
present, or the piece of metal will be dissolved); arsenic is 
deposited on the copper as a gray coating possessing a some- 
what metallic appearance. (Memorandum. — An equivalent 
proportion of copper goes into solution. The experiment 
forms an illustration of a kind of chemical change appropriately 



ARSENIC. 



179 



termed substitution.) Pour off the supernatant liquid from the 
copper, wash the latter with water, dry it by means of a piece 
of filter-paper, and finally place it at the bottom of a clean, 
dry, narrow test-tube, or a Berzelius tube, and sublime as 
described in reaction 1, again noticing the form of the result- 
ing crystals. The tube containing the sublimate may be 
reserved for subsequent comparison with a similarly obtained 
sublimate of antimonious oxide. This test for arsenic was 
introduced by Reinsch, in 1843. 

Note. — Copper itself frequently contains arsenic, a fact that 
may not, perhaps, cause any trouble to the student, who is per- 
forming experiments in practical chemistry with known substances, 
for educational purposes; but when the analyst proceeds to the 
examination of substances of unknown composition, he must 
assure himself that neither his apparatus nor materials already 
contain the element for which he is searching. 

The defection of arsenic in metallic copper is best accomplished 
by boiling, in a retort or distilling-flask, a mixture of a few grains 
of the sample with five or six times its weight of ferric hydroxide 
or chloride (free from arsenic) and excess of hydrochloride acid. 
The arsenic is thus volatilized in the form of chloride, and may 
be condensed in water and detected by means of hydrogen sul- 
phide (see reaction 6, p. 183) or by Eeinsch's test. The ferric 
chloride solution is, if necessary, freed from any trace of arsenic 
by evaporating once or twice to dryness with excess of hydro- 
chloric acid. 

Fig. 35. 




The hydrogen test for arsenic. 



3. The Hydrogen Test or Marsh's Test. — Generate hydrogen 
in the usual way by the interaction of zinc and dilute sul- 
phuric acid, a bottle of about four of six ounces capacity 
being used, and a funnel-tube and short delivery-tube })assing 



throuo^h the cork as shown in Fi 



ir. oo. 



Dry the escaping 



180 THE METALLIC RADICALS. 

hydrogen (except in rough experiments, when this is scarcely 
necessary) by adapting to the delivery-tube a short piece of 
wider tubing filled with fragments of dried calcium chloride 
(a). To the other end of the drying-tube fit a piece of 
narrow tubing ten or twelve inches long, made of hard glass, 
and having its outlet end reduced to a small bore by drawing 
it out in the flame of the blowpipe. When the hydrogen has 
been escaping for a sufficient number of minutes and at such 
a rate as to warrant the student in concluding that all the air 
originally jyresent in the bottle has been expelled, kindle the jet, 
and then "pour eight or ten drops of the aqueous arsenical 
solution, or three or four drops of the acid or alkaline solution 
previously prepared, into the funnel-tube, washing the liquid 
into the generating-bottle by means of a little water. By the 
action of the zinc and sulphuric acid, the arsenous compound 
is reduced to the state of arsenic, and the latter combines with 
some of the hydrogen to form arseniuretted hydrogen, or 
hydrogen arsenide, AsHg. 



AsA + 12H = 


= As, + 


QB.fi 


Arsenous Hydrogen 


Arsenic 


Water 


anhydride (nascent) 







As, -f 12H = 4ASH3 

Arsenic Hydrogen Hydrogen 

(nascent) arsenide 

Hold a piece of glazed earthenware or porcelain (the lid 
of a porcelain crucible (b) if at hand) in the burning hydro- 
gen jet ; a brown spot of arsenic is deposited on the cold sur- 
face. Collect several of these deposits, and retain them for 
future comparison with antimony deposits similarly obtained. 
To ensure the conversion of the whole of the arsenic into 
hydrogen arsenide, it is advisable, toward the end of the 
operation, to add a few drops of solution of stannous chloride 
in hydrochloric acid to the generating-flask ; this causes the 
precipitation of the arsenic in a state of very fine division, in 
which it is readily acted upon by the nascent hydrogen. 

The separation of arsenic in the flame is due to the decomposi- 
tion of the hydrogen arsenide by the heat. The cool porcelain at 
once condenses the arsenic, and thus prevents its oxidation to 
arsenous anhydride (which would othenvise take place at the 
outer edge of the flame). 

Hold a small beaker (c), or wide test-tube, over the flame 
for a few minutes ; a white film of arsenous anhydride, As,Og, 



ARSENIC. 181 

will be deposited slowly, and may be further examined in 
contrast with the similarly produced film of antimonous oxide. 

During these experiments the effect produced by the burning 
of the hydrogen arsenide on the color of the hydrogen flame 
should be noted ; the flame acquires a characteristic dull, livid, 
bluish tint. 

Apply the flame of a gas-lamp to the middle of the hard 
glass delivery-tube (d, Fig. 35); the hydrogen arsenide is 
decomposed as before, but the liberated arsenic condenses in 
the cool part of the tube, beyond the flame, as a dark metallic 
mirror. The tube may be removed and kept for comparison 
with antimony deposit. 

Note 1. — The zinc and sulphuric acid used for Marsh's test 
must be free from arsenic. Zinc, like copper, frequently contains 
arsenic as impurity. When a specimen, free from arsenic, is met 
with, it should be reserved for analytical experiments. Sulphuric 
acid, free from arsenic, can usually be purchased, but samples 
must always be tested as to their purity. 

Note 2. —In delicate and important applications of Marsh's 
test, magnesium may be substituted for zinc with safety, arsenic 
not being found in magnesium. Magnesium in rods is convenient 
for this purpose. Both magnesium and zinc, if perfectly pure, 
interact with acids extremely slowly; but the addition of a very 
small quantity of chloroplatinic acid, at once promotes an abun- 
dant evolution of hydrogen. Platinum, however, has a tendency 
to hold back arsenic. According to Dyer, rod zinc has a similar 
tendency, while granulated zinc at once gives hydrogen arsenide. 

Note 3. — Sulphuric acid, which is often used for drying gases, 
decomposes hydrogen arsenide. Calcium chloride is the appro- 
priate desiccating agent for this gas. 

Note 4. — The original apparatus proposed by Marsh, in 1836, 
was a U-shaped tube, one limb of which was short, and closed by 
a stopcock, so that the whole of a small quantity of hydrogen 
arsenide could be collected, and afterward examined at leisure. 

Note 5. —On account of the exceedingly poisonous character of 
hydrogen arsenide, the preceding test and the next one should be 
conducted in a well-ventilated fume-cupboard. 

4. Fleitmann's Test. — Generate hydrogen by heating a 
concentrated solution of sodium or potassium hydroxide and 
some pieces of zinc in a test-tube, to near the boiling point (Zn-|- 
2NaOH=H,+Na,ZnO.,, see p. 187). Add a drop of arsenical 
solution. Now spread over the mouth of the tube a cap of 
filter-paper moistened with one drop of solution of silver nitrate. 



I 



182 THE METALLIC RADICALS. 

Again heat the tube, taking care that the liquid itself shall 
not spurt up on to the cap. A plug of cotton wool may 
even be placed in the mouth of the test-tube to arrest this 
spurting. The arsenical compound is reduced to arsenic, 
which unites with the hydrogen, as in Marsh's test ; and the 
hydrogen arsenide passing up through the cap interacts with 
the silver nitrate, producing a purplish-black spot (of silver). 

ASH3 + 3H.,0 + 6AgN03 = H3ASO3 + 6HNO3 + 6Ag. 

Note 1, — This reaction is valuable, since it enables the analyst 
quickly to distinguish arsenic in the presence of antimony. During 
the reduction of an antimony compound by nascent hydrogen 
in an acid solution, a portion of the antimony is converted into 
hydrogen antimonide, SbHg, which also acts upon silver nitrate; 
whereas if the reduction is carried out in an alkaline solution, 
hydrogen antimonide is not formed, and hence the effect just 
described is not produced. 

Note 2. — Aluminium answers as well as zinc for Fleitmann's 
test (Gatehouse), or magnesium may be used; or instead of zinc 
and alkali, sodium amalgam containing only a small porportion 
of sodium may be employed (Davy). 

Note 3. — If the filter-paper cap is moistened with solution of 
mercuric chloride and then exposed to the action of hydrogen 
arsenide, a yellow stain, AsHHg^Clg, results ; becoming after a 
time brown, AsHg3Cl3, and then black, As2Hg3. 

The formation of a yellow stain when hydrogen arsenide, in 
small quantity, interacts with mercuric chloride (see Note 3, above) 
has been made the basis of a modification, elaborately described in 
the U. S. P., of Gutzeit' s test for arsenic. The student is advised 
to consult the pharmacopceia for minute details of the precautions 
necessary in employing the test in the examination of chemicals, 
generally, for traces of arsenic. 

5. Bettendorff's Test. — To a solution of stannous chloride 
in concentrated hydrochloric acid add a very small quantity 
of any arsenical solution. Arsenic then separates, especially 
on the application of heat, producing a yellowish and then 
brownish color, a grayish-brown turbidity, or even a sediment 
of gray-brown flocks, according to the quantity present. Much 
water prevents the reaction, and its presence must therefore 
be avoided as far as possible; indeed a liquid saturated with 
hydrochloric acid gas gives the best results. The presence of 
arsenic in sulphuric or hydrochloric acid, or in tartar emetic, 
etc., may be detected by means of this test. Nitrates, such 
as bismuth oxynitrate, must first be heated with sulphuric acid 



ARSENIC. 183 

to remove the nitric acid radical before applying this test for 
arsenic. The stannous salt is converted into stannic salt 
during the reaction? 

The foregoing are the most important reactions of arsenic, 
whether existing in the arsenous or arsenic condition; of the 
following reactions 10 and 11 may be employed to distinguish 
arsenous and arsenic compounds from each other. 

6. Through an acidulated arsenous solution pass hydrogen 
sulphide; a yellow precipitate of arsenous sulphide, As^Sg, is 
at once produced. Add an alkali-metal hydroxide or hydro- 
sulphide to a portion of the precipitate; it readilly dissolves. 
The precipitate consequently would not be produced on pass- 
ing hydrogen sulphide through an alkaline arsenous solution. 

When arsenous sulphide is dissolved in a solution of a hydro- 
sulphide, a soluble meta-thiarsenite (Qelov, fheion, sulphur) is 
produced. Thus when ammonia hydrosulphide is used the solu- 
tion contains meta-thiarsenite — 

As^Sg + 2NH,HS = 2NH,AsS2 + H^S 

When a hydroxide is used, a mixture of metarsenite and meta- 
thiarsenite is obtained — 

2As,S3 + 4]SraOH = NaAsO, + SNaAsS^ + 21Ifi 

To another portion of the arsenous sulphide precipitate, 
well drained, add concentrated hydrochloric acid ; it is insol- 
uble — unlike antimonous sulphide. (Neither sulphide is sol- 
uble in dilute hydrochloric acid). 

Note 1. — A yellow sulphide is also produced in an acid solution 
of a cadmium salt by the action of hydrogen sulphide, but this 
sulphide is insoluble in alkaline liquids. Under certain circum- 
stances tin, too, yields a yellow sulphide, but tin is otherwise 
easily distinguished. 

Note 2. — A trace of arsenous sulphide is sometimes met with in 
the sulphur distilled from arsenical pyrites. It may be detected 
by digesting the sulphur in ammonia water, filtering, and evapor- 
ating to dryness; a yellow residue of arsenous sulphide is obtained 
if that substance be present. 

7. Through an acidulated solution of arsenic acid, or any 
other arsenate, pass a rapid current of hydrogen sulphide; a 
yellow precipitate of arsenic sulphide, As.,S.-, is produced, but 
precipitation takes place very slowly in cold solutions. Brauner 
and Tornicek state that by a slow current the arsenic acid is 
gradually reduced to arsenous acid, and a yellow precipitate 
is formed which consists of arsenous sulphide mixed with sul- 



184 THE METALLIC RADICALS. 

phur. The reaction is more rapid if the solution be warmed. 
The precipitate is soluble in alkali-metal hydroxides and 
hydrosulphides. When it is dissolved in a hydrosulphide 
the solution contains a thiarsenate, while a hydroxide produces 
a mixture of arsenate and thiarsenate. 

8. To an aqueous solution of arsenous anhydride add two 
or three drops of solution of cupric sulphate, and then 
cautiously add dilute ammonia water, drop by drop, until 
a green precipitate is obtained. The production of this 
precipitate is characteristic. To a portion of the mixture add 
an acid; the precipitate dissolves. To another portion add 
an alkali; the precipitate dissolves. The solubility of the 
precipitate in both acid and alkali shows the advantage of 
testing a suspected arsenical solution by means of litmus- 
paper before applying this reaction, and if found to be acid, 
cautiously adding alkali, or if alkaline, adding acid, till 
neutrality is obtained ; or a special reagent — copper ammonio- 
sulphate — may be used. {See note to reaction 11.) 

The precipitate consists of cupric arsenite, CuHAsOg, or 
Scheele^s Green. In the pure state, or mixed with cupric acetate 
or, occasionally, with cupric carbonate, it is used as a pigment 
under different names, such as Brunswick Green and Schwein- 
furth Green, by painters and others. 

9. Apply the test just described to a solution of arsenic 
acid or other arsenate ; a somewhat similarly colored precipi- 
tate of cupric arsenate is obtained. 

10. Repeat reaction 8, substituting silver nitrate for cupric 
sulphate : in this case a yellorv precipitate of silver arsenite, 
Ag.^AsOg, is produced, also soluble in acids and alkalies. 

11. Apply the silver nitrate test of the preceding reaction 
to a solution of arsenic acid or other arsenate ; a brown 
precipitate of silver arsenate, Ag^AsO^, is formed. 

Copper and Silver Reagents for Arsenic. — The last four reactions 
may be performed with increased delicacy and certainty of result 
if the copper and silver reagents be previously prepared in the 
following manner: — To cupric sulphate (test-solution) add ammo- 
nia water until the blue precipitate at first formed is nearly, 
but not quite, redissolved ; filter and use the liquid as an arsenic 
reagent, labeling it Cupric Ammonium Sulphate Test-Solution 
(U. S. P.). Treat solution of silver nitrate (about 1 part in 20) 
in the same way, and label it Silver Ammonium Nitrate Test- 
Solution (U. S. P.). The composition of these two salts will be 
referred to subsequently. 



ARSENIC. 185 

Arsenous and Arsenic Compounds. — While many reagents 
may be used for the detection of arsenic, only the behavior 
with silver nitrate will immediately and distinctly indicate in 
which state the arsenic exists ; for the two sulphides and the 
two copper precipitates, though differing in composition, resem- 
ble each other in appearance, whereas the two silver precipitates 
differ in color as well as in composition. 

Soluble arsenates give precipitates of insoluble arsenates on 
the addition of solutions of salts of barium, calcium, zinc, 
and other metals. 

Arsenic, when it exists as arsenic acid or other arsenate, 
does not rapidly respond to the test with hydrogen sulphide 
or nascent hydrogen. Hence, if its presence, as arsenate, is 
suspected, the liquid under examination should be warmed 
with a little sulphurous acid — or treated with hydrochloric 
acid until slightly acid and then with solution of sodium thio- 
sulphate — before the addition of hydrogen sulphide. 

Antidote in Cases of Arsenical Poisoning. — The most 
effective antidote in these cases is recently precipitated moist 
ferric hydroxide, administered as soon as possible. It is 
perhaps best administered in the form of the mixture obtained 
by adding magnesia (Magnesii Oxidum, U. S. P.), previously 
rubbed up to a smooth, thin mixture with cold water, to a dilute 
solution of ferric sulphate (one part of Liquor Ferri Tersul- 
phatis, U. S. P., to about three of water). This arsenic 
antidote (Ferri Hydroxidum cum Magnesii Oxido) is official. 
Emetics should also be given, and the stomach-pump, or a 
common India-rubber tube, used as a siphon, be applied Tas 
quickly as possible. 

The above statements regarding the antidote for arsenical poison- 
ing may be verified by mixing the various substances together, 
filtering, and proving the absence of arsenic in the filtrate by 
applying some of the foregoing tests. 

Mode of Action of the Antidote.— The action of the magnesia is 
to precipitate ferric hydroxide, Fe(OH).^ — magnesium sulphate, 
MgSO^, being formed, which is at least harmless, if not beneficial, 
under the circumstances. The interaction between ferric hydrox- 
ide and arsenous acid results in the formation of insoluble ferrous 
arsenate. {See also p. 158.) 



k 



186 THE METALLIC RADICALS. 

QUESTIONS AND EXERCISES. 
What is the formula of a molecule of arsenic? — In what form does 
arsenic occur in nature? — Describe the characters of white arsenic. 
Name the official preparations of arsenic. — By what method may %vhite 
arsenic be reduced to metallic arsenic? — Give the formulae of arsenous 
and arsenic acids and anhydrides. — Explain, by equations, the reactions 
which occur in converting white arsenic into sodium arsenate. — Why is 
anhydrous instead of crystallized sodium arsenate employed officially? — 
Describe the manipulations necessary to obtain white arsenic in its char- 
acteristic crystalline form. — How is Reinsch's test for arsenic applied, and 
under what circumstances may its indications be fallacious ? — Give the 
details of Marsh's test for arsenic, and the precautions to be observed. 
Explain the reactions by diagrams. — What peculiar value has Fleitmann's 
test for arsenic? — Describe the conditions under which hydrogen sulphide 
becomes a trustworthy test for arsenic. — How may a trace of arsenous 
sulphide be detected in sulphur? — How are salts of copper and silver 
applied as reagents for the detection of arsenic? — How are arsenites 
distinguished from arsenates? — Mention the best antidote in cases of 
arsenical poisoning ; describe the process by which it may be most quickly 
prepared, and explain its action. 



ANTIMONY: Sb (Stibium). Atomic weight, 119.3. 

Occurrence, etc. — Antimony occurs in nature chiefly as anti- 
monious sulphide, Sb2S3, stibnite. The crude or black antimony 
of pharmacy is this native sulphide fi-eed from impurities by 
fusion: it has a striated, crystalline, lustrous fracture; subsequently 
powdered and, if it contains any soluble salt of arsenic, the latter 
removed by digestion in ammonia water, it forms the grayish- 
black crystalline ^j^/rZ/fec^ black antimony. The metal is obtained 
from the sulphide by roasting, the resulting oxide being reduced 
with charcoal and sodium carbonate. The resulting scoria is 
known as crocus of antimony or glass of antimony. Antimony is 
also obtained from the native sulj^hide by heating it with iron, 
ferrous sulphide being formed at the same time. Metallic anti- 
mony is an important constituent of type-metal, Britannia metal, 
and the best varieties of peiuter. The old pocula emetica, or ever- 
lasting emetic cups, were made of antimony; wine kept in them 
for a day or two -was said to have acquired an emetic quality. 

* Antimony has very close chemical analogies with arsenic. Like 
arsenic, it unites with iodine to form a tri-iodide (Sbig). A 
bromide, SbBrg, also is known. 

Antimonious and Antimonic Chlorides. 

Experiment 1. — Boil about half an ounce of antimonious 
sulphide with four or five times its weight of hydrochloric 
acid in a dish placed in a fume-cupboard or in the open-air ; 
hydrogen sulphide is evolved and solution of antimonious 
chloride, SbClg, is obtained. 



ANTIMONY. 187 

Sb^Sg + 6HC1 -= 2SbCl3 + 3H2S 

Antimonious Hydrochloric Antimouious Hydrogen 

sulphide acid chloride sulphide 

This solution, cleared by subsidence, is what is commonly 
known as buffer of antimony. If pure sulphide has been used in 
its preparation, the liquid is nearly colorless; but much of that 
met with in veterinary pharmacy is simply a by-product in the 
generation of hydrogen sulphide from native ferruginous anti- 
monious sulphide and hydrochloric acid, and is more or less 
brown from the presence of ferric chloride. It not infrequently 
darkens in color on keeping; this is due to absorption of oxygen 
from the air, and conversion of light-colored ferrous into dark- 
brown ferric chloride or oxychloride. It is a powerful caustic. 

True buffer of anfimony, SbClg, is obtained on evaporating 
the above solution to a small volume, and distilling the residue. 
The butter condenses as a white crystalline semi-transparent mass 
in the neck of the retort ; at the close of the operation it may be 
melted and allowed to flow into a bottle, which should be well 
stoppered. It is highly corrosive. 

Antimony pentachloride or anfimonic chloride, SbCl^, is a fuming 
liquid, obtained by passing chlorine over the trichloride. 

Antimonious Oxychloride. 

Experiment 2. — Boil the solution of antimonious chloride 
produced in experiment 1, and pour it into several ounces 
of water; a white precipitate of antimonious oxychloride, 
Sb^OgClg, is produced, some antimonious chloride remaining 
in the supernatant acid liquid. 

This precipitate is the substance formerly known as pulvis 
Algarofhi, pulvis angelicus, or mercurius vitce. It varies somewhat 
in composition, according to the amount of water with which the 
chloride may be mixed ; but, on standing under water, gradually 
becomes crystalline, and has the composition given above. 



4SbCl3 


+ 


5H,0 = 


= ^hfifi\ + lOHCl 


ntimonio'u 


s 


Water 


Antimonious Hydrochloric 


chloride 






oxychloride acid 



Antimonious Oxide. , 

Experiment 3. — Wash the precipitate obtained in experi- 
ment 2, thoroughly with water, by decantation {xee p. 116), 
and add solution of sodium carbonate ; the oxychloride is 
decomposed, and antimonious oxide, ^l\0,., is produced. The 
latter is of a light buff or grayish-white color, or quite white if 
absolutely free from iron, insoluble in water, soluble in hydro- 



188 



THE METALLIC RADICALS. 



chloric acid, fusible at a low red heat. The moist antiraonious 
oxide may be well washed and employed for experiment 4, or it 
may be dried on a water-bath. At temperatures above 212° F. 
(100° C), it absorbs oxygen and other antimony oxides are 
formed. The presence of the latter may be detected on boil- 
ing the powder in solution of acid potassium tartrate, in which 
antimonious oxide, Sb^Og, is soluble, but antimonic anhydride, 
^hfi.^ and antimony tetroxide, Sb^O^ or Sb^Og (Sb^O^, Sb^OJ, 
are insoluble. 



Sbp.Cl, + 

Antimonious 
oxy chloride 



Na,C03 

Sodium 
carbonate 



= Sbp, + 2KaCl + CO^ 

Antimonious Sodium Carbonic 

oxide chloride anhydride 



The higher antimony oxide, Sb.^ O^, termed antimonic oxide or 
anhydride, corresponding to arsenic anhydride, is obtained by 
decomposing the pentachloride with water, or by boiling metallic 
antimony with nitric acid. The variety obtained from the chloride 
differs in saturating power from that obtained from the metal, and 
is termed metantimonic acid. 



Tartar Emetic. 

Experiment 4.^ — Mix the moist antimonious oxide obtained 
in experiment 3, with about an equal quantity of potassium 
bitartrate (6 parts of the latter to 5 of the dry oxide) and suffi- 
cient water to form a paste ; set aside for a day to facilitate com- 
plete combination; boil the product with water, and filter; the 
resulting liquid contains antimony and potassium tartrate, 
tartarated antimony, or tartar emetic (emetic, from ^/jJw, emeo, 
I vomit) KSbOC.HPg. 



4KHC,H,0, + Sbp, = 

Acid potassium Antimonious 



tartrate 



oxide 



4KSbOC,Hp, 

Tartar emetic 



2Hp 

Water 



On evaporation, the salt is obtained in colorless transparent 
crystals. These contain water of crystallization, and are 
represented by the formula [K(SbO)C,Hpj2» H,0 Anti- 
monii et Potassii Tartras, U. S. P. . 

Tartar emetic is very commonly represented (as above) as 
potassium antimonyl tartrate (SbO^= antimonyl). It seems almost 
certain, however, that it is really the potassium salt of tartranti- 
monious acid, HSbC^H^O^, in which antimony is present as a 
part of the acid radical. A solution of this acid (which is very 
unstable), also the barium and several other salts, have been 
obtained. 



ANTIMONY. 189 

Tartar emetic is soluble in water, and slightly so in 60 per- 
cent, alcohol. A solution in alcohol and white wine forms the 
official Vitium Antimonii, U. S. P. 

Sulphurated Antimony and other Antimony 
Oxysulphides. 

Experiment 5. — Boil a few grains of antimonious sulphide 
and of sulphur with sodium hydroxide solution in a test-tube, 
and filter (or on a larger scale, 10 ounces of antimonious sul- 
phide, 10 of sulphur, and 5 of sodium hydroxide for 2 hours, 
frequently stirring, and occasionally replacing water lost by 
evaporation). Into the filtrate, while still hot, stir dilute sul- 
phuric acid until the liquid is slightly acid to test-paper ; an 
orange-red precipitate is produced. It is a mixture of anti- 
mony pentasulphide, ^h^._^, with some oxide (Sb^Og, or pos- 
sibly Sb^Og) and some free sulphur. The oxide results from 
the interaction of antimonious sulphide and sodium hydroxide 
in the presence of air. 

This is one of the many varieties of mineral Jcermes, so-called 
from their similarity in color to the insect kermes. Kermes is the 
name, now obsolete, of the Coccus llicis, a sort of cochineal-insect, 
full of reddish juice, and used since the earliest times for dyeing. 
The term mineral kermes was apparently applied originally to the 
amorphous or precipitated orange antimonious sulpide, Sb2S3. It 
afterward included any mixture of this with oxysulphide and 
pentasulphide. A brownish-red variety may be prepared without 
the addition of any free sulphur; the color of the precipitate is 
then affected by the temperature as well as by the state of dilution 
of the alkaline liquid when the acid is added. When this 
alkaline liquid is boiled in contact with air, oxygen is absorbed 
and unites with some of the antimony, displacing sulphur which, 
in turn, converts some antimony trisulphide into pentasulphide. 
Kermes may be formed by fusion as well as by boiling the com- 
ponents in aqueous solution. 

Explanation of processes. — The antimony sulphides and oxides, 
like those of arsenic interact with the sulphides and hydroxides of 
certain metals to form salts which are more or less soluble in water. 
Thus when antimonious sulphide is dissolved in hot solution of 
sodium hydroxide, sodium metantimonite, NaSbOj, and meta- 
thiantimonite, NaSbS.^, are formed: in the presence of sulphur, 
sodium metantimonate, NaSbO,, and sodium thiantimonate are 
produced, the former of which is sparingly soluble. 



2Sb,S, + 


4NaOH 


= NaSbO., + 3NaSbS, + 


2H,,0 


itimonious 


Sodium 


Sodium Sodium 


Water 


sulphide 


liydroxide 


metantimonite meta-tliiautimouite 





190 



THE METALLIC RADICALS. 



4Sb,S3 + 8S + ISNaOH = SNaSbOg + SNa^SbS, + OH.O 

Antiraonious Sulphur feodium Sodium Sodium Water 

sulphide hydroxide metantimonate thiantimouate 

The salts so formed in hot solutions are not all stable in cold solu- 
tions, and antimony oxides, or sulphides, or both, are deposited 
when the hot solutions cool. Thus sodium meta-thiantimonite 
decomposes yielding sodium ortho-thiantimonite, NagSbSg, and a 
deposit of antimonius sulphide, Sb^Sy: 

SNaSbS^ = Na3SbS3 + Sb^Sg 

In the preparation of kermes, therefore, the acid should be added 
to the solution obtained on boiling up the necessary ingredients, 
before any precipitate has separated (that is, before the solution 
is cool), if uniformity of product is desired. 



2NaSbS2 + H^SO, 

Sodium meta- Sulphuric 
thiantimonite acid 



4NaSbO, -j 

Sodium " 
metantimonite 

2]S"a,SbS, + 

Sodium 
thiantimouate 



2H,S0, = 

Sulphuric 
acid 

Sulphuric 
acid 



2NaSb03 + 

Sodium Sulphuric 

metantimonate acid 



: Na^SO, 
Sodium 
sulphate 

2Na,S0, 
Sodium 
sulphate 

SNa^SO, 

Sodium 

sulphate 

Na^SO, - 

Sodium 
sulphate 



Sb„S, 



2^3 



H.S 



Antimonious Hydrogen 
sulphide sulphide 

+ Sbp, + 2HP 

Antimonious Water 
oxide 



f Sb,8, 

Antimonic 
sulphide 

Sb.O^ - 

Antimonic 
oxide 



Hydrogen 
sulphide 

Water 



The oxides and sulphides indicated in these equations, are all 
precipitated when the acid is added, and form the A'arieties of 
Kermes. 

Analytical Reactions of Antimonious Salts. 

1. Through an acidified antimonious solution pass hydro- 
gen sulphide ; an orange precipitate of amorphous antimonious 
sulphide, Sb2S3, is produced. It has the same composition as 
the crystalline black sulphide into which, indeed, when dried, 
it is quickly converted by heat. Like arsenous sulphide, it 
is soluble in solutions of alkali-metal hydrosulphides and 
hydroxides. Collect a portion on a filter and, when well 
drained, add concentrated h3xlrochloric acid ; it dissolves — 
unlike arsenous sulphide. 

Antimonic sulphide, Sb.,S-, corresponding to arsenic sul- 
phide, AS2S., is known. It is formed on passing hydrogen 
sulphide through an acidulated solution of antimonic chloride, 
SbClj, or, less pure, on boiling black antimonious sulphide 
and sulphur with a caustic alkali, and decomposing the result- 
ing filtered liquid by means of an acid. 



ANTIMONY. 191 

2. Dilute two or three drops of a solution of antimouious 
chloride with water ; a white precipitate of antimonious oxy- 
chloride is produced (see experiment 2, p. 187). The pro- 
duction of a precipitate in these circumstances, distinguishes 
antimony from arsenic, but the reaction is not capable of being 
applied as a delicate discriminating test in analysis. Add a 
sufficient quantity of hydrochloric acid to dissolve the precipi- 
tate, and boil a piece of copper in the solution, as directed in 
the corresponding test for arsenic (reaction 2, p. 178) ; anti- 
mony is deposited on the copper. Wash, dry, and heat the 
copper in a test-tube as there described ; the antimony, like 
the arsenic is volatilized off the copper and oxidized, and the 
white oxide condenses on the side of the tube ; but the subli- 
mate, from its low degree of volatility, condenses close to the 
copper; moreover, it is generally non-crystalline, rarely in 
acicular or octahedral crystals. 

Shake out the copper and boil water in the tube for several 
minutes. Do the same with the arsenical sublimate similarly 
obtained. The latter slowly dissolves, and may be recognized 
in the solution by means of silver ammonium nitrate ; the 
antimonial sublimate is insoluble. 

3. Perform the operations described under Marsh's test for 
arsenic (reaction 3, p. 178), placing the apparatus in a well- 
ventilated fume-cupboard and carefully observing all the de- 
tails there mentioned, but using a few drops of solution of anti- 
monious chloride or of tartar emetic instead of the arsenical 
solution. Antimony hydride, antiraoniuretted hydrogen, or 
hydrogen antimonide, SbHg, is formed and may be decomposed 
in the same way as arsenic hydride. 

To one of the arsenical spots on the porcelain lid (p. 181) 
add a drop of a dilute solution of bleaching-powder ; it quickly 
dissolves. Do the same with an antimony spot ; it is unaffected. 
Heat more quickly causes the volatilization of an arsenic than 
of an antimony spot; ammonium hydrosulphide more readily 
dissolves the antimony than the arsenic. 

Boil the water for several minutes in the beaker or wide 
test-tube containing the arsenical sublimate (p. 181); it 
slowly dissolves, and may be recognized in the solution by the 
yellow precipitate given on the addition of solution of silver 
ammonium nitrate. The antimonial sublimate, similarly 
treated, does not dissolve. 

Pass a slow current of hydrogen sulphide through the deli- 
very-tube removed from the hydrogen apparatus (p. 181), and 
when the air has been expelled from the tube, gently heat 



192 THE METALLIC RADICALS. 

that portion coutaiuing the deposit of arsenic ; the latter will be 
converted into a yellow sublimate of arsenous sulphide. Ke- 
move the tube from the hydrogen-sulphide apparatus, and 
repeat the experiment with an antimony deposit ; it is con- 
verted into an orange antimouious sulphide, which, moreover, 
owing to inferior volatility, condenses nearer to the flame than 
the arsenous sulphide does. 

Pass dry hydrochloric acid gas through the two delivery-tubes. 
This is accomplished by adapting first one tube and then the 
other, by means of a cork, to a test-tube containing a few lumps 
of common salt, upon which a little sulphuric acid is poured 
prior to the insertion of the cork. The antimouious sulphide dis- 
solves and disappears ; the arsenous sulphide is unaffected. 

Antidote in cases of Antimonial Poisoning. — The introduc- 
tion of poisonous doses of antimonial compounds into the 
stomach is fortunately quickly followed by vomiting. If vomit- 
ing has not occurred, or apparently to an insufficient extent, 
tannic acid in any form may be administered (infusion of tea, 
nut-galls, cinchona, oak bark, or other astringent solutions or 
tinctures), an insoluble antimony tanuate being formed, and 
absorption of the poison being thereby somewhat retarded. 
The stomach-pump or stomach-siphon must be applied as 
quickly as possible. 

Recently precipitated moist ferric hydroxide is also, accord- 
ing to T. and H. Smith, a complete precipitant of antimony 
from its solutions, the chemical action being probably, they 
say, similar to that which takes place between ferric hydrox- 
ide and arsenous anhydride. It may be given in the form of 
a mixture of ferric chloride with either sodium carbonate or 
other soluble carbonate or bicarbonate, or with magnesia. 

These statements may be verified by mixing together the vari- 
ous substances, filtering and testing the filtrate for antimony in the 
usual manner. 



QUESTIONS AND EXERCISES. 



What is the composition and source of ^'BlacTc Antimony^^ ? — In what 
alloys is metallic antimony a characteristic ingredient? — What is the 
quantivalence of antimony as far as indicated by the formulae of the offi- 
cial preparations? — Show by an equation how "Butter of Antimony" is 
prepared. — Write out equations or diagrams expressive of the reactions 
which occur in converting antimouious chloride into oxide. — What is the 
formula of Tartar Emetic? — Explain by aid of equations the preparation 
of sulphurated antimony. — Give a comparative statement of the tests for 
arsenic and antimony. — How is antimony detected in the presence of 
arsenic? 



TIN. 193 

TIN : Sn. Atomic weight, 118.1. 

Occurrence, etc. — The chief ore of tin is stannic oxide, SnOg, 
occurring in veins under the name of tinstone, or in alluvial depos- 
its as stream-tin. The oldest mines are those of Cornwall. Much 
tin is now imported from Australia. The metal is obtained by . 
reducing the roasted and washed ore by means of charcoal or 
anthracite ^ coal at a high temperature, and is purified by slowly 
heating, when the pure tin, fusing first, is run off, a somewhat less 
fusible alloy of tin, with small quantities of arsenic, copper, iron, 
or lead remaining. The latter is known as block fin ; the former 
heated until brittle and then hammered or let fall from a height 
splits into prismatic fragments resembling those of starch or of 
columnar basalt, and is named dropped or grain tin. Good tin on 
being bent emits a crackling noise, which is termed the ' 'cry' ' of 
the tin, and is caused by the friction of its crystalline particles on 
each other. 

Uses. — Tin is an important constituent of such alloys as pewter, 
Britannia metal, solder, speculum-metal, bell-metal, gun-metal 
and bronze. It is very ductile, and may be rolled into plates, or 
into leaves known as tin-foil, varying from -i^\-^ to yoVxr ^^ ^^ inch i| 

in thickness. Common tin foil, however, usually contains a large i 

proportion of lead. The reflecting surface of looking-glasses, was ' 

formerly always an amalgam of tin and mercury, produced by ' 

carefully sliding a plate of glass over a sheet of tin foil on which j 

mercury had been rubbed, and then excess of mercury had been jj 

poured — but pure silver, deposited from a solution, is now largely 
employed. Pins are made of brass or iron wire on which tin is 
deposited. Tin-plate, of which common utensils are made, is iron 
alloyed with tin by dipping acid-cleansed sheet-iron which has 
been immersed in melted tallow, into vessels containing melted -, 

tin, and subsequently heating it in a bath of melted tallow, which, ■ 

by preventing oxidation, enables the tin more completely to alloy f 

with the iron. Tin tacks are in reality tinned iron tacks. Tin 
may be granulated by melting it and triturating it briskly in a hot 
mortar; or by shaking melted tin in a box, on the inner sides of 
which chalk has been rubbed. It may also be obtained in thin 
bell-shaped or corrugated fragments (Tin. U. S. P. ), by melting it in 
a ladle, and, as soon as it is fluid, pouring it from the height of a 
few feet into water. Powdered tin has been used medicinally as 
a mechanical irritant to promote expulsion of worms. 

Tin forms two sets of compounds which are called stannous 
and stannic, respectively. They correspond to the two oxides, 
SnO and SnOg. 

^ Anthracite (from avQpa^, anthrax, a buvninsj^ coal), or stone coal, differs 
from the ordinary bHHmJnous or cakiufi coal in containiii.u- less volatile 
matter, and therefore, in burning without flame. It gives a higher 
temperature, and from its non-cakiTig properties, is, iu furnace operations, 
more manageable than bituminous coal. 

13 



194 THE METALLIC RADICALS. 



Stannous Chloride. 

-r=^ Experiment 1. — Warm a fragment of tin with hydrochloric 
acid; liydrogen escapes and a solution of stannous chloride, 
SnCl2, is formed. It may be retained for future experiments. 

The sokition obtained by dissolving tin in hot concentrated 
hydrochloric acid (some undissolved tin being kept in the liquid) 
and dissolving the stannous chloride crystals so obtained in 10 
parts of water, constitutes the "Stannous Chloride Test-Solution," 
U. S. P. 

Solid Stannous Chloride. — By the evaporation of the above 
solution, stannous chloride is obtainable in crystals, SnClg, 2H2O. 
It is a powerful reducing agent, even a dilute solution precipita- 
ting gold, silver and mercury from their solutions, converting ferric 
and cupric into ferrous and cuprous salts, and partially deoxidi- 
zing arsenic, manganic, and chromic acids. It absorbs oxygen 
from the air and is decomposed when added to a large quantity of 
water unless some acid be present. It is used as a mordant in 
dyeing and calico-printing. 

Stannic OMoride. 

Experiment 2. — Pass chlorine through a portion of the 
solution of the stannous chloride of the preceding experiment; 
a solution of stannic chloride, SnCl^, is formed. Or add 
hydrochloric acid to the stannous solution, boil, and, in a 
fume-cupboard, slowly drop in nitric acid until no more fumes 
are evolved; again stannic chloride results. Reserve the 
solutions for subsequent experiments. 

Stannic Oxide, or Anhydride, and Stannates. 

Experiment 3. — Boil a fragment of tin with nitric acid, 
evaporate to dryness, and strongly ignite the residue; light 
buff-tinted stannic anhydride, 8n02, is produced. Heat the 
stannic anhydride with excess of solid potassium or sodium 
hydroxide ; stannate of the alkali-metal (K^SnOj or Na^SnO,) 
results. Dissolve the stannate in water, and add hydrochloric 
acid; white gelatinous stannic acid, H^SnO.^, is precipitated. 

Stannic acid is also obtained on adding a solution of a 
caustic alkali to solution of stannic chloride; it is soluble in 
excess of acid or of caustic alkali. The precipitate in this 
case appears to correspond to the formula H^SnO^, but it 
easily loses water and becomes H2Sn03. 



TIN. 195 

SnCl, + 4K0H = H^SnO, + 4KC1 

Sn(OH), = HP -h H^SnO, 

The product of the action of nitric acid on tin is also an acid, 
but it is different from ordinary stannic acid inasmuch as it is con- 
verted by hydrochloric acid into metastannic chloride, which is 
insoluble in moderately concentrated hydrochloric acid although 
soluble in water. It is called metastannic acid, and its molecule 
probably has the composition expressed by the formula H2oSn502o. 
If dried over sulphuric acid, or at 100° C., it becomes Hj^SugO^g 
(sodium salt, HgNagSugO^g). This latter substance is also pro- 
duced by gently heating the acid resulting from the interaction 
of potassium hydroxide and stannic chloride. 

5H,SnO, = H,oSngO,,+ 5H,0 

Both acids yield buff-colored stannic oxide or anhydride, Sn02, 
when strongly heated. The latter is employed in polishing plate 
under the name of putty poivder. Sodium stannate, Na2Sn03, SHgO, 
is used as a mordant by dyers and calico-printers under the name 
X)f tin prepare-liquor. 

Analytical Reactions of Tin Compounds. 

Stannous or Stannic Salts. — Heat any solid compound of 
tin with a mixture of potassium cyanide and sodium carbonate 
on charcoal in the inner flame of the blowpipe. Hard glob- 
ules of tin separate which, w^hen cut by a knife, exhibit a 
characteristic bright white surface. 

Reactions of Stannous Salts. 

1. Through a dilute solution of a stannous salt (stannous 
chloride, for example) pass hydrogen sulphide ; a brown pre- 
cipitate of stannous sulphide, SnS, results. Pour off the 
supernatant liquid, add ammonia water to the moist precipi- 
tate (to neutralize acid), and then ammonium hydrosulphide 
solution; the precipitate is at least partially dissolved. The 
addition of some sulphur and the application of heat may be 
necessary to effect complete solution. 

Aqueous solution of ammonium hydrosulphide becomes yellow 
when a day or two old, and then contains excess of sulphur, some 
of that element having become displaced by oxygen absorbed from 
the air. As a consequence of this (or by the aid of the added sul- 
phur), the stannous sulphide, SnS, takes up sulphur and dissolves 
to form ammonium thiostanate. From this solution vellow stim- 



196 THE METALLIC RADICALS. 

nic sulphide (usually mixed with sulphur) is precipitated by the 
addition of excess of an acid. 

2SnS + -INH.HS + S^ = 2(NHJ,SnS3 + 2H2S 
(NHJ^SnSg + 2HC1 = 2NH,C1 + H,S + SnS^ 

2. To a solution of a stannous salt add solution of potassium 
or sodium hydroxide ; a white precipitate of stannous hydrox- 
ide, Sn(OH)^, is produced. Add excess of the alkali ; the 
precipitate dissolves. Boil the solution ; some of the tin is 
reprecipitated as blackish stannous oxide, SnO. Ammonia 
water gives a similar white precipitate, insoluble in excess. 
The alkali-metal carbonates do the same, carbonic anhydride 
escaping. 

Reactions of Stannic Salts. 

1. Through a solution of a stannic salt (stannic chloride, 
for example) pass hydrogen sulphide; a yellow precipitate of 
stannic sulphide, ^uS^, results. Pour off the supernatant 
liquid, and to the moist precipitate add ammonia water (to 
neutralize acid), and then ammonium hydrosulphide ; the pre- 
cipitate dissolves. 

Kate. — In this reaction the presence of much hydrochloric acid 
must be avoided, and the formation of the precipitate is facilitated 
if the solution be warmed. Stannic sulphide, like the arsenic and 
antimony sulphides, dissolves in solutions of alkali-metal sulphides 
or hydrosulphides, with formation of definite crystallizable fhio- 
stannates (MgSnS.^. 

Anhydrous stannic sulphide, prepared by sublimation, has a 
yellow or orange lustrous appearance, and is know as mosaic gold. 
It was formerly used by decorators as bronzing-powder, but the 
latter now usually consists of powdered bronze-leaf. 

2. To a solution of a stannic salt add potassium or sodium 
hydroxide; a white precipitate of stannic acid, H^SnOg, is 
produced. Add excess of the alkali ; the precipitation dis- 
solves. Boil the mixture ; no reprecipitate occurs — a reac- 
tion by means of which stannic may be distinguished from 
stannous salts. 

Ammonia water gives a similar precipitate slowly soluble in 
excess. Potassium and sodium carbonates do the same, carbonic 
anhydride escaping; after a time the stannic salt is again deposited, 
probably as potassium or sodium stannate. Ammonium carbonate 
and all the bicarbonates give a precipitate of stannic acid, insol- 
uble in excess. 



OOLD. 197 

Separation of Antimony and Tin. — If a piece of iron wire be 
placed in the acid (HCl) solution of the two metals, a black pre- 
cipitate of antimony is formed, and the tin is reduced to the stan- 
nous condition; the latter may be detected by the addition of mer- 
curic chloride solution, when a white precipitate of mercurous 
chloride is produced. 

2HgCl2 + SnCl^ = SnCl, + 2HgCl 

Antidotes. — In cases of poisoning by tin salts {e.g., dyers' tin- 
liquor), solution of ammonium carbonate should be given; and 
white of egg is also said to form an insoluble precipitate. Vom- 
iting should be induced, and the stomach-pump, or stomach- 
siphon, applied. 

GOLD: Au. Atomic weight, 195. 7. 

Occurrence, etc. — Gold occurs in the free state in nature, occa- 
sionally in nodules or nuggets, but in alluvial deposits commonly 
in a finer state of division termed gold dust. Gold is. separated 
from sand, crushed quartz, or other earthy matter with which it 
may be associated, by agitation with water, when the gold, from 
its relatively greater specific gravity, falls to the bottom of the 
vessel first, the greater part of the lighter mineral matter being 
carried away by the water. From the rich sediment the gold is 
dissolved out by mercury; the amalgam is filtered and afterward 
distilled, when the mercury volatilizes and gold remains. The 
amalgamation may be facilitated by the use of sodium, as 
described under silver. From even the poorest ores gold may be 
dissolved by solution of potassium cyanide in presence of air. 
{See Faraday on gold leaf, 1857.) 8KCn + 4Au + 0^+ 2H.p = 
4KAu(CN), + 4K0H. 

Pure gold is too soft for use in the form of coins for general cir- 
culation. Gold coin is usually an alloy of copper and gold, that 
of the United States, France, and Germany contains about 10 per- 
cent, of copper; the gold coinage of Great Britain contains 1 part 
of copper to 11 of gold. Australian gold coins contain silver in- 
stead of copper as alloy. Jewellers^ gold varies in quality, every 
24 parts containing 18, 15, 12, or 9 parts of gold, these alloys 
being technically termed 18, 15, 12, or 9 carat fine, the reckoning 
being in the old ''parts per 24," instead of the more usual parts 
percent. Articles made of the better j:]ualities are usually stamped 
by authority. Trinkets of inferior intrinsic worth are often tliinly 
coated with pure gold by electro-deposition or otherwise. The so- 
called mijstery gold is an alloy of about 1 part of platinum and 2 
parts copper with a little silver. It resists the action of concen- 
trated nitric acid. The action of aqua regia and then ammonia 
reveals the presence of copper in it. Gold leqfi^ nearly pure goUl ( 1 J 
to 4 percent, of silver or copper, according to the lighter or darker 



198 THE METALLIC RADICALS. 

tint required) passed between rollers till it is about -g-^ of an inch 
in thickness and then hammered between sheets of animal mem- 
brane, termed gold-beaters' skin, and calf-skin vellum till it is 
reduced to i ^ oVo o o^ 2 o oV oo ^f an inch in thickness. It may even 
hammered till 280,000 leaves would be required to form a pile an 
mch thick. 

Experiment. — Place a fragment of gold {e.g. gold leaf) in 
ten to twenty drops of aqua regia (a mixture of three parts 
of nitric and four or five of hydrochloric acids), and set aside 
in a warm place (in a fume-cupboard); a solution of chlor- 
auric acid, HAuCl^, (formerly regarded as a solution of gold 
trichloride or auric chloride, AuCl.,), results. Evaporate to 
dryness, fuse, moisten with water, pour off the clear liquid, 
and retain it for subsequent experiments. Such a solution is 
official (Gold Chloride Test Solution, U. S. P.). Chlorauric 
acid is very deliquescent. Sodium chloraurate, NaAuCl^ is a 
readily crystallizable salt. A mixture of equal parts of anhy- 
drous gold chloride and anhydrous sodium chloride is official 
(^Auri etSodii Chloridum). 

This reaction is of analytical interest; for in examining a sub- 
stance suspected to be or to contain metallic gold, solutions would 
have to be effected in the above way before reagents could be 
applied, as gold is insoluble in hydrochloric, nitric, or any other 
single acid. 

Analytical Reactions of Gold. 

1. Through a few drops of solution of a chloraurate or of 
an auric salt (the chloride, AuCl.^, is the only convenient auric 
salt) pass hydrogen sulphide in the cold ; a black precipitate 
of aurous-auric sulphide, Au^S.,, is produced. This precipitate 
dissolves, with difficulty, in yellow ammonium sulphide. If 
the hydrogen sulphide be passed through a boiling solution, a 
brown precipitate of metallic gold is produced. 

2. A solution of a chloraurate or of a gold salt add a ferrous 
salt, and set aside ; metallic gold is precipitated in the form of 
a yellowish or reddish-brown lustrous powder, a ferric salt 
remaining in solution. Oxalic acid, also, and most free metals 
similarly precipitate gold, the supernatant liquid acquiring a 
purplish hue. 

This is a convenient way of preparing pure gold, or fine gold, as 
it is termed, or of working up the gold residues from laboratory 
operations. The precipitate, after boiling with hydrochloric acid, 
washing and drying, may be obtained as a button by mixing with 



PLATINUM. 



199 



an equal weight of borax or potassium bisulphate and fusing in a 
crucible in a good furnace. 

3. Add a few drops of dilute solutions of stannous and 
stannic chlorides to a considerable quantity of distilled water ; 
pour the liquid, a small quantity at a time, into a very dilute 
solution of auric chloride, and stir well ; the mixture assumes 
a purple tint, and flocks of a precipitate, known as the Purple 
of Cassius (from the name of the discoverer, M. Cassius), are 
produced. The presence of more than a trace of a free acid 
must be avoided. 

Purple of Cassius is also formed on immersing a piece of tin 
foil in a solution of auric chloride; it is said to be a mixture of 
auric, aurous, stannic, and stannous oxides ; but recent experi- 
ments suggest that it may be merely stannic acid, mechanically 
colored with metallic gold. It is the coloring agent in the finer 
varieties of ruby glass. 



PLATINUM : Pt. Atomic weight, 193-3. 

Occurrence. — Platinum, like gold, occurs in nature in the free 
state, the chief sources of supply being Mexico, Brazil and Siberia. 
Alloyed with iridium, osmium, and other rare metals, it is met with 
in the form of gray grains or powder in alluvial deposits, frequently 
associated with gold. It is separated from the soil by washing. 

Uses. — Platinum is chiefly employed in the form of foil, wire, 
crucibles, spatulas, cajjsules, evaporating-dishes and stills, for the 
purposes of the analyst and chemical manufacturer. It is toler- 
ably hard, fusible with very great difficulty, and not dissolved by 
hydrochloric, nitric, or sulphuric acid; but it is somewhat readily 
attacked by alkaline substances. It is dissolved by aqua regia 
with production of chloroplatinic acid, HgPtClp. It forms fusible 
alloys with lead and other metals, and with phosphorous an easily 
fused phosphide. None of these substances, therefore, nor mix- 
tures which may yield any of them, should be heated in platinum 
vessels. Hammered platinum vessels are the most durable. They 
are best cleaned by fusing a small quantity of potassium bisulphate 
in them, and dissolving out the fused salt by boiling in water. 
They should not be either heated or cooled very suddenly. They 
should only be heated in the upper portion of the Bunsen or blow- 
pipe-flame, as exposure to the lower parts of these flames, which 
contain incompletely burnt gases, give rise to the formation of a 
brittle carbide. Red-hot platinum vessels should not be permitted 
to come into contact with any metallic support, unless one made 
of platinum. 

The specific gravity of platinum at 15.5° C. is 21.5 ; and that of 
the allied metal, iridium, 22.4. 



200 THE METALLIC RADICALS. 

Experiment. — Place a fragment of platinum in a small 
quantity of aqua regia, and set the vessel aside in a warm 
place (in a fume-cupboard), adding more acid from time to 
time if necessary; a solution of chloroplatinic acid, HgPtClg 
(formerly regarded as simply a solution of platinic chloride, 
PtCl ), results. Evaporate the solution to remove the excess 
of acid, and complete the desiccation over a water-bath. Dis- 
solve the residue in water, and retain the solution for sub- 
sequent experiments and as a reagent for the precipitation of 
potassium and ammonium salts. Platinum treated in this 
manner, and the resulting chloroplatinic acid dissolved in 
water, forms ''Platinic Chloride Test Solution," U. S. P. 

Analytical Reactions of Platinum. 

1. ' Through a few drops of a solution of a chloroplatinate, 
or of a platinic salt to which an equal quantity of a solution of 
sodium chloride has been added, pass hydrogen sulphide : a 
dark-brown precipitate of platinic sulphide, PtS^, is produced. 
Filter, wash, and add ammonium hydrosulphide ; the precipi- , 
tate dissolves with some difficulty. 

If sodium chloride be not present in the above reaction, the 
precipitated sulphide will contain platinous chloride, and may 
detonate if heated. 

2. Add excess of sodium carbonate and some sugar to a 
solution of a chloroplatinate or of platinic chloride, and boil ; 
a black precipitate of metallic is produced. 

Platinum Mack is the name of this precipitate. It possesses in 
a high degree a quality common to many substances, of which 
platinum is a notable example — that, namely, of absorbing or 
occluding gases. In its ordinary state, after well washing and 
drying, it absorbs from the air, and retains, many times its own 
volume of oxygen. A drop of ether or alcohol placed on it is 
rapidly oxidized, the platinum becoming hot. This action may be 
prettily shown by pouring a few drops of ether into a beaker, 
loosely covering the latter with a card, through which there passes 
a platinum wire, the lower end of which terminates in a short coil 
or helix near the surfiice of the ether : on now warming the helix 
in a flame and then rapidly introducing it into the beaker, it will 
become red-hot and continue to glow. In this experiment partial 
combustion goes on between the etlier vapor and the concentrated 
oxygen of the air, the ])roducts of the oxidation revealing them- 
selves by the odor (chiefly that of formaldehyde). 



PLATINUM. 201 

3. To a solution of a chloroplatinate or of platinic chloride 
add solution of 'ammonium chloride ; a yellow crystalline 
precipitate of ammonium chloroplatinate, (NH^)2PtClg, is 
produced. When it is slowly formed in dilute solutions, the 
precipitate is obtained in minute orange prisms. Collect the 
precipitate, dry it, and heat it in a small porcelain crucible ; it 
is decomposed, and metallic platinum, in a finely divided 
gray state {spongy platinum), remains. 

Potassium chloride, KCl, gives a similar precipitate of potassium 
chloroplatinate, K2PtClg. Heat decomposes the potassium salt 
into Pt+ 2X01+201.2, the chlorine escaping and the potassium 
chloride remaining with the platinum. 

The corresponding sodium compound, Na2PtClg, is soluble in 
water. 

In working up the platinum residues from laboratory operations, 
the mixture should be dried, burnt, boiled successively with hydro- 
chloric acid, water, nitric acid, water, then dissolved in aqua 
regia, excess of acid being removed by evaporation. Ammonium 
chloride is then added, the precipitate washed with water, dried, 
ignited, and the resulting spongy platinum retained or converted 
into chloroplatinic acid. It is by such processes that the native 
platinum is treated to free it from the rare metals palladium, 
rhodium, osmium, ruthenium and iridium. The spongy platinum 
is converted into the massive condition by hammering it when hot, 
or by fusing it in the flame of the oxyhydrogen blowpipe. 

Occlusion of gooses by spongy platinum. — Spongy platinum has 
great power of occlusion. A small piece held in a jet of hydrogen 
which is escaping into the air, causes combination of the hydrogen 
with the oxygen (of the air) occluded by the platinum. The heat 
given out by this combination eventually raises the platinum to a 
red heat and the red-hot platinum kindles the hydrogen jet. 
Dobereiner's self-lighting lamp was constructed to take advantage 
of this property — the apparatus being essentially a vessel in which 
hydrogen was generated by the action of dilute sulphuric acid on 
zinc, and so arranged that on opening the stopcock a jet of 
hydrogen impinged on some spongy platinum contained in a small 



QUESTIONS AND EXERCISES. 

Define tinstone, stream-tin., hloclc-tin, grain-tin, tin plate. — What i? the 
difference between stannic acid and inetastannic acid? — State the a]>i)lica- 
tions of tin in the arts. — Mention the chief tests for stannous and stannic 
salts. — Natne the best antidote in cases of poisonin,<>' by tin solutions. — 
How is sold dust separated from the earthy matter with which it is 
naturally associated?— State the average thickness of gold leaf. — What 
effect is produced on gold by hydrochloric, nitric and nitrohydrochloric 
acids respectively? — j^y what reagents may metallic gold be precipitated 



202 THE METALLIC RADICALS. 

from solution? — How is "purple of Cassius " prepared? — Whence is 
platinum obtained ? — Why are platinum utensils peculiarly adapted for 
use in chemical laboratories ? — How is chloroplatinic acid prepared ? — 
Name the chief tests for platinum. — What is " platinum black " ? — What 
is meant \>j occlusion of gases? — Describe an experiment illustrating the 
power of occluding gases, possessed by metallic platinum. — How is 
"spongy platinum" produced? — By what process may platinum be 
recovered from residues? 



Directions for applying the reactions described in 
the foregoing paragraphs to the analysis of 
an aqueous solution of a compound of one of the 
elements arsenic and antimony ; also of tin in the 
form of a stannic salt.^ 

Acidulate the liquid with hydrochloric acid, and pass 
hydrogen sulphide through it: — 

An orange precipitate indicates antimony. 

A yellow precipitate indicates arsenic or a stannic salt. 
To distinguish between arsenic and stannic salt, test the 
original solution with ammonia water and with potassium 
hydroxide. No precipitates : arsenic indicated. For behavior 
of stannic salt compare p. 196. 

The results may be confirmed by the application of other 
tests. 



Directions for applying the reactions described in 

THE foregoing PARAGRAPHS TO THE ANALYSIS OF AN 
AQUEOUS SOLUTION OF COMPOUNDS OF BOTH ARSENIC 
AND ANTIMONY ; ALSO POSSIBLY CONTAINING TIN IN THE 
FORM OF STANNIC SALT. 

Acidulate a small portion of the liquid with hydrochloric 
acid, and pass hydrogen sulphide through it. 

Note 1. — If the hydrogen sulphide precipitate is unmistakably 
orange, antimony may be put down as present, and arsenic only 
further sought by the application of Fleitmann's test to the 

' Stannic sohitions are rarely met with, but these solutions are dealt 
with here, and in tbe analytical directions immediately following, 
because in the ordinary course of systematic analysis, tin (Avhether 
present originally as stannous or as stannic salt) is eventually precipitated 
as yellow stmniic sulphide along with arsenic and antimony sulphides, 
prior to its separation from arsenic and antimony. 



q UA LIT ATI VE A NAL YSIS. 



203 



original solution, or to the solution of the sulphides in aqua regia ^ 
freed from sulphur by boiling. 

Note 2. — Antimonious sulphide is far less readily soluble than 
arsenous sulphide in solution of ammonium carbonate. But 
this fact possesses limited analytical value, since, in the case of 
mixed sulphides, much antimonious sulphide will prevent a small 
quantity of arsenous sulphide from being dissolved by the ammo- 
nium carbonate, while much arsenous sulphide will carry a small 
quantity of antimonious sulphide into the solution. When the 
proportions are, apparently, from the color of the precipitate, less 
wide, solution of ammonium carbonate may sometimes be found 
useful in roughly separating the one sulphide from the other. 
On filtering and neutralizing the alkaline solution by adding an 
acid, the yellow arsenous sulphide is reprecipitated. The orange 
antimonious sulphide, and any stannic sulphide present, will 
remain on the filter. 

Note 3. — Solution of potassium hydrogen sulphite is said by 
Wohler to be a good reagent for separating arsenous and anti- 
monious sulphides, the former being soluble, the latter insoluble 
in the liquid. 

Note 4. — Another reagent for separating arsenous from anti- 
monious and stannic sulphides is concentrated hydrochloric acid. 
As little water as possible must be present. On boiling, anti- 
monious and stannic sulphides dissolve, while arsenous sulphide 
remains insoluble. The liquid, slightly diluted, filtered, mixed 
with more water, and again treated with hydrogen sulphide, gives 
orange antimonious sulphide, mixed with stannic sulphide when 
tin is present. The presence of arsenic may be confirmed by the 
application of Fleitmann' s test to the original solution. 

The two processes now to be described for the detection of 
arsenic and antimony are rather long, and require much care in 
their performance; but they are useftil, because a small quantity 
of antimony in presence of much arsenic, or vice versa, may be 
detected by their means. The method for detecting tin will be 
described later (p. 205.) 

Detection of Arsenic and Antimony. 

First process. — Generate hydrogen, as for Marsh's test 
(p. 179) and pass it through a small wash-bottle containing 
solution of lead acetate, to free from any trace of hydrogen 
sulphide, and then through a dilute solution of silver nitrate 
contained in a test-tube. When the hydrogen apparatus is 
in good working order, pour into the' generating bottle a 

^ Aqua Regia is a mixture of liydrochloric and nitric acid. Aci(h()n 
Nitrohydrochlorieum, U. S. P. It was so-called from its property of dis- 
solving gold, the "king" of metals. 



204 THE METALLIC RADICALS. 

quantity of the origiDal solution to be examined, adding it 
gradually to prevent violent action. After the gas has been 
passing for five or ten minutes, examine the contents of the 
test-tube ; arsenic, if present, will be found in the solution in 
the state of arsenous acid, — 

ASH3 + 3Hp + GAgNOg = H3ASO3 + 6HNO3 + 6Ag ; 

while antimony, if present, will be found in the black pre- 
cipitate that has fallen, according to the following equation: 

SbH, + 3AgN03 = SbAg3 + 3HNO3 

The arsenous radical may be detected in the clear, filtered, 
supernatant liquid, which still contains much silver nitrate, 
by cautiously neutralizing with very dilute ammonia water 
or by adding a few drops of solution of silver ammonium 
nitrate, yellow silver arsenite being produced. The antimony 
may be detected by washing the black precipitate, boiling it 
in an open dish with solution of tartaric acid, adding hydro- 
chloric acid, filtering and passing hydrogen sulphide through 
the solution, orange antimonious sulphide being precipitated. 
(Hofmanu.) 

Second process. — Obtain the metallic deposit in the middle 
of the delivery-tube as already described under Marsh's test. 
Act on the deposit with hydrogen sulphide gas, and then with 
hydrochloric acid gas, as detailed in reaction 3 of antimony 
(p. 191). If both arsenic and antimony are present, the deposit, 
after the action of hydrogen sulphide, will be found to be of 
two colors, the yellow arsenous sulphide being usually farther 
removed from the heated portion of the tube than the orange 
antimonious sulphide. Moreover, subsequent action of hydro- 
chloric acid gas causes the disappearance of the antimonious 
sulphide, which is converted into chloride and carried off in 
the stream of gas. 

The chief objection to this process is the liability of the operator 
mistaking sulphur, deposited from the hydrogen sulphide by the 
action of heat, for arsenous sulphide. But the presence or absence 
of arsenic is easily confirmed by apj^lying Fleitmann's test to the 
original solution, while the process is most useful for the detection 
of a small quantity of antimony in the presence of much arsenic. 
On the whole, Hofmann's method is to be preferred. 



COPPER. 



205 



Detection of Tin. 

During the generation of hydrogen arsenide and antimonide in 
Marsh's apparatus, any stannic chloride present in the original 
solution under examination is gradually reduced, with deposition 
of metallic tin. After the testing for arsenic and antimony is 
concluded, pour out the contents of the generating bottle into a 
dish; take out- the fragments of zinc, first detaching from them 
any black powdery or spongy deposit; separate the liquid by 
filtration and wash the residue (which contains any reduced tin 
together with impurities derived from the zinc). Boil the residue 
with a small quantity of dilute hydrochloric acid; filter, if 
necessary, and test the filterate for stannous salt by adding mer- 
curic chloride. A white precipitate of mercurous chloride indi- 
cates the presence of tin. (Compare p. 221.) 



The student may now proceed to the analysis of aqueous solu- 
tions of salts of any of the metallic elements hitherto considered. 
The method followed may be that for the separation of the pre- 
vious three groups, hydrogen sulphide being first passed through 
the solution to precipitate arsenic and antimony (also tin, if stannic 
salt be present). The liquid, after the removal by filtration, of 
any hydrogen sulphide precipitate and ebullition to expel 
hydrogen sulphide, is examined by means of the other group- 
reagents for metals of the iron, zinc, barium, and magnesium 
groups and then for alkali metals. (Compare pp. 106, 128, 145, 
170, 171.) Three or four solutions at least should be examined 
before proceeding to the next group of metals — copper, mercury, 
etc. 

COPPER : Cu. Atomic weight, 63.1. 

Occurrence, etc. — The commonest ore of this metal is copper 
pyrites, a copper and iron sulphide, CuFeSg, occurring in Cornwall; 
Australia and Kussia supply malachite, a hydroxy carbonate; much 
ore is also imported from Spain and from South America. It 
is smelted in enormous quantities at Swansea, South Wales, a 
locality peculiarly fitted for the operation on account of its prox- 
imity to the coal-field, and its position as a seaport. By Holl way's 
economical method of smelting copper pyrities and other sul- 
phides, after the sulphide is once melted, air is driven, not over, 
as usual, but through the mass; the combustion of the sulphur 
then becomes self-supporting, and is greatly accelerated. 

The alchemists termed this metal Venus, perha})S on account of 
the beauty of its lustre, and gave it her symbol 9, a compound 
hieroglyphic also indicating a mixture of gold o , and a certain 
hypothetical substance called acrimony >^, the corrosive nature 
of which was symbolized by the points of a ^Maltese cross To 
this day the blue show-bottle in the shop-window of the phar ■ • t 



206 THE METALLIC RADICALS. 

is occasionally ornamented by such a symbol, indicating, possibly, 
that the blue liquid in the vessel is a preparation of copper. 

Copper forms two sets of salts, which are distinguished as cupric 
and cuprous salts, and may be regarded as related to the oxides, 
CuO and CU2O, respectively. Cupric oxide, or black copper 
oxide, CuO, may be prepared by heating fragments of copper to 
low redness on a piece of earthenware in an open fire. Cuprous 
iodide, Cul, will be subsequently referred to as a convenient form 
in which to remove iodine from solution, while the formation of 
cuprous oxide, CU2O, under given circumstances, will come under 
notice as an indicator of the presence of sugar in a liquid. 

Cujyric Sulphate, CuSO.SHp {Cupri Sulphas, U. S. P.), blue 
vitriol, blue stone, or copper sulphate is the only copper compound 
much used in pharmacy. It is a by-product in silver-refining 
(Ag2S0^4-Cu=Cu04+2Ag). Some is formed in roasting copper 
pyrites. In the latter case, some iron sulphide and copper sul- 
phide are oxidized to sulphates; but the low red heat finally 
employed decomposes the ferrous sulphate; while the cupric sul- 
phate is unaffected; the latter is purified by crystallization from a 
hot aqueous solution, though frequently much ferrous sulphate 
remains in the crystals. Cupric sulphate is also prepared by 
dissolving in dilute sulphuric acid the black oxide, CuO, obtained 
in annealing copper plates (CuO + H2SO^=CuSO^+H20); it may 
also be obtained bv boiling copper with three times its weight of 
sulphuric acid (2H2SO,+ Cu = CuSO,+S02+2H20), diluting, 
filtering, evaporating, and crystallizing. In this process some 
black cuprous sulphide also is formed. 

Anhydrous Cupric Sulphate, CuSO^, is a yellowish-white powder 
prepared by depriving the ordinary blue crystals of cupric sul- 
phate of their water of crystallization by exposing them to a tem- 
perature of about 400° F. (204° C). It is used in testing alcohol 
and similar spirituous liquids for water, becoming blue if the 
latter be present. 

Experiment. — Cupric Nitrate. — Digest copper in dilute 
nitric acid. When action has ceased, evaporate and crystal- 
lize. If the crystals form at a temperature of 73° to 80° F. 
(22.7 to 26.6° C), they are prismatic, Cu(N03)2, SH^O; at 
lower temperatures, tabular, Cu(N03)2,6H20. 

3Cu + 8HNO3 = 3Cu(N03)2 + 2N0 + 4H,0 

Copper Nitric acid Cupric acid Nitric oxide Water 

Verdigris (from verdi-gris, Sp., green-gray) is Copper Oxy- 
acetate Cu20(C,H302),, obtained by exposing alternate layers 
of copper and fermenting refuse grape-husks to the action of air. 

The modes of forming Cupric Sulphicl, Hydroxide, Oxide, 
Ferrocyanide, and Arsenite, as well as Metallic Copper, are 
incidentally alluded to in the following analytical paragraphs. 



COPPER. 



207 



Analytical Reactions of Cupric Salts. 

1. Pass hydrogen sulphide through ao acidulated solution 
of a cupric salt ; a black precipitate of cupric sulphide, CuS, 
is produced, which is insoluble in dilute acids. 

2. To an aqueous solution of a cupric salt add ammonium 
hydrosulphide; by this reagent, also, cupric sulphide is pre- 
cipitated, insoluble in excess. 

Xofe. — Cupric sulphide is not altogether insoluble in ammonium 
hydrosulphide if free ammonia or much ammonium salt be present ; 
it is insoluble in potassium and sodium hydrosulphides. 

3. Immerse a piece of iron or steel, such as the point of a 
penknife or a piece of iron wire, in a few drops of a solution 
of a cupric salt ; copper is deposited on the iron, with its 
characteristic color, an equivalent quantity of iron passing into 
solution. If a sufficient quantity of iron is employed and the 
experiment is allowed to continue long enough, the copper is 
entirely precipitated — 

CuSO, + Fe = FeSO, + Cu 

By this reaction copper may be recovered on the large scale 
from waste solutions, old hoop or other scrap iron being thrown 
into the liquors. 

4. Add ammonia water to a solution of cupric sulphate ; 
cupric hydroxide, Cu(0H)2, of a light-blue color, is precipi- 
tated. Add excess of ammonia ; the precipitate is redissolved, 
forming a blue solution of cupric ammonium salt, so deep in 
color as to render ammonia an exceedingly delicate reagent 
for copper. From this ammoniacal solution alcohol precipi- 
tates a dark-blue crystalline mass (CuSO^, 4NH3, H^O) w^hich, 
on heating to 150° C, loses water and two molecules of ammo- 
nia, becoming CuSO^, 2NH3, and at 200° C, it loses another 
molecule of ammonia, becoming CuSO,, NH3. Other soluble 
cupric salts yield similar compounds. 

A cupric ammonium sulphate may be obtained in large crystals 
by adding stronger ammonia water to poAvdered cupric sulphate 
until the salt is dissolved, placing the liquid in a test-glass or 
cylinder, cautiously pouring in twice its volume of nearly anhydrous 
alcohol or methylated spirit, taking care that the liquids do not 
become mixed, tying a piece of bladder over the mouth of the 
vessel, and setting aside for some weeks in a cool place. (Witt- 
stein). 



208 THE METALLIC RADICALS. 

5. Add a solution of potassium or sodium hydroxide to a 
cupric solution ; cupric hydroxide, Cu(OH)^, is precipitated, 
insoluble in excess. Boil the mixture in the test-tube with 
excess of potassium or sodium hydroxide ; the cupric hydrox- 
ide is decomposed, losing the elements of water, and becoming 
converted into black anhydrous cupric oxide, CuO. 

6. Add solution of potassium ferrocyanide, K^FeCyg, to an 
aqueous cupric solution ; a reddish-brown precipitate of cupric 
ferrocyanide, Cu^FeCyg, is produced. This is an extremely 
delicate test for copper. 

7. Add solution of potassium iodide to an aqueous cupric 
solution ; in moderately concentrated solutions of a precipitate 
of cuprous iodide, Cul, is produced, with simultaneous libera- 
tion of iodine which imparts a yellow or brown color to the 
solution. 

2CuS0, + 4KI = 2X^80, + 2CuI + I, 

On adding to the mixture a solution of sulphurous acid (or of 
ferrous sulphate), the color due to the free iodine is removed, 
and the nearly white cuprous iodide can be recognized. Even 
in very dilute cupric solutions a yellow coloration is produced 
on the addition of potassium iodide, which becomes violet on 
the addition of starch paste (see Iodides). This test is even 
more delicate than the ferrocyanide test, but care must be taken 
to ascertain that the solution of potassium iodide employed 
does not contain free iodine. 

8. To a cupric solution add solution of arsenous acid, 
and cautiously neutralize with alkali ; green cupric arsenite, 
CuHAsOg, is produced. 

jNIost copper salts impart a green color to the Bunsen flame. 
Cupric chloride imparts a bluish color. 

Antidotes. — In cases of poisoning by compounds of copper, 
iron filings should be administered, the action of which is 
explained in reaction 3. Potassium ferrocyanide may also be 
given (see reaction 6). Albumin forms with copper salts a 
compound insoluble in water, hence raw eggs may be adminis- 
tered, vomiting being induced or the stomach-pump, or 
stomach-siphon, applied as speedily as possible. 



MERCURY. 209 

QUESTIONS AND EXEECISES. 

Name the sources of copper. — Give equations showing how Cupric Sul- 
phate is prepared on the small and large scale. — Calculate how much 
Crystallized Cupric Sulphate may be obtained from 100 parts of cupric 
sulphide. Ans. 261.05 parts. — How may Cupric Oxide be prepared?— 
Write down the formula of Verdigris. — What is the analytical position of 
copper ? — Mention the chief tests for copper. — How may copper be sepa- 
rated from arsenic ? — Why is finely divided iron an antidote in poisoning 
by copper ? 



MERCURY : Hg. Atomic weight, 198.5. 

Occurrence. — Mercury occurs in nature as sulphide, HgS, form- 
ing the ore cinnabar (an Indian name expressive of something red), 
and is obtained from Spain, California, Eastern Hungary, China, 
Japan, and Peru. 

Preparation. — The metal is separated by roasting off the sulphur 
and then distilling ; or better, by distilling with lime, which com- 
bines with and retains the sulphur. 

Properties. — Mercury (Hydrargyrum, U. S. P.), is a silver- white 
lustrous metal, liquid at ordinary temperatures. It boils at 675°F. 
(357° C), and at -39° F, (-40° C.) solidifies to a malleable mass 
of octahedral crystals. Its specific gravity is 13. 535. When quite 
free from other metals, it does not tarnish, and its globules roll 
freely over a sheet of white paper without leaving any streak. 

Formula. — The formula of the mercury molecule is Hg and not 
Hg2, because (at all events at the high temperature at which alone 
the weight of its vapor can be determined) the quantity of mercury 
vapor which occupies the same space as that occupied by 2 grammes 
of hydrogen under the same conditions is 198.3 grammes, and not 
twice this quantity (see p. 58). Analogous facts have been 
observed with reference to the vapors of zinc and cadmiuin. Mer- 
cury, like iron, copper, etc., forms two sets of salts. These are 
called mercurous and mercuric salts, and correspond to the oxides, 
HggO and HgO, respectively. 

Amalgams. — The mixture or compound formed on fusing metals 
together is usually termed an alloy [ad and ligo, I bind) ; if mercury 
is a constituent, an amalgam [fj,d/ia-yjua, malagma, from fm/dnm,), 
?7ialasso, I soften, the_ presence of mercury lowering the melting- 
point of such a mixture). Most metals form amalgams. Electric 
amalgam, the exciting material which is rubbed against the glass 
plate of an electrical machine, commonly consists of 1 part each of 
tin and zinc with 3 parts of mercury. Sodium amalgam has already 
been mentioned (page 94). 

Medicinal Compounds. — The comixninds of mercury used in 
medicine are all obtained from the metal. The metal itself, rub- 
bed with chalk, or with confection of roses and powdered liquorice- 

14 



^mm 



210 THE METALLIC RADICALS. 

root, or with lard and suet, until globules are not visible to the 
unaided eye, is often used in medicine. The preparations are : — 
Hijilrargijrum cum Greta, U. S. P., or Gray Powder; Massa Hydrar- 
gyri, U. S. P. ; Unguentum Hydrargyri, U. S. P., Mercurial Oint- 
ment, and Unguentum Hydrargyri Dilutum, U. S. P., Blue Oint- 
ment. There is also an official Mercurial Plaster {Emplast7^um 
Hydrargyri). Their therapeutic effects are probably due, not to 
the large quantity of metallic mercury in them, but to small quan- 
tities of black and red oxide which occur in them through the 
action of the oxygen of the air on the finely divided metal. The 
proportion of oxide or oxides varies according to the age of the 
specimen. All these medicinal preparations of metallic mercury 
are indefinite and unsatisfactory, and that through no fault of the 
pharmacist. They much need investigation by pharmacists and 
therapeutists. 

Mercurous and Mercuric Iodides. 

Experiment 1. — Rub together small quautities of mercury 
and iodine, controlling the rapidity of combination by adding, 
at the outset and at intervals during the operation, a few drops 
of alcohol, which by evaporation absorbs heat, and thus keeps 
down the temperature. The product is either mercuric iodide, 
mercurous iodide, or a mixture of the two, together with mer- 
cury or iodine, if excess of either has been employed. If the 
two elements have been weighed out in atomic proportions, 
198.3 of mercury to 125.9 of iodine (about 8 to 5), a green 
or grayish-green powder results from their union, which consists 
chiefly of mercurous iodide, Hgl; if in the proportions of the 
atomic weight of mercury to twice that of iodine (198.3 to 
twice 125.9, or about 4 to 5), red mercuric iodide, Hgl^, results 
— an iodide that is official, but made in another way (see p. 
211). Mercurous iodide should be made and dried without 
heating, and with as little exposure to light as possible. Mer- 
curic iodide may be removed from it by well washing with 
alcohol. Mercurous iodide (Hydrargyri lodidum Flavum, 
U. S. P.), can also be obtained as a bright yellow precipitate 
by adding a solution of potassium iodide to a solution of mer- 
curous nitrate, care being taken that excess of the former is 
avoided. (See reaction 2, p. 220). 

Mercurous iodide is decomposed slowly by exposure to light, 
and quickly by the action of heat, into mercuric iodide and mer- 
cury. Mercuric iodide, occurring as an impurity in mercurous 
iodide may be detected by digesting in ether (in which mercurous 
iodide is insoluble), filtering, and evajjorating to dryness; mer- 



MERCURY. 211 

curie iodide remains. Mercuric iodide is stable, and may be 
sublimed in scarlet crystals without decomposition. (For the 
mechanical details of the method by which a specimen of the 
crystals may be obtained, and the precautions to be observed, see 
corrosive sublimate, p. 213). 

Red and Yelloiv Varieties of Mercuric Iodide. — In condensing, 
mercuric iodide is at first yellow, afterward acquiring its character- 
istic scarlet color. This may be shown by smearing or rubbing 
a sheet of white paper with the red iodide, and then holding the 
sheet before a fire or over a flame for a few seconds. As soon as 
the paper becomes sufficiently hot the red iodide changes to 
yellow, and the salt does not quickly regain its red color when 
cold if the paper is carefully handled. But if the salt be pressed 
or rubbed in any way, the portions touched immediately return to 
the scarlet condition. These color changes are accompanied by 
changes in crystalline form. The red modification, stable at 
ordinary temperatures, forms tetragonal crystals; the yellow modi- 
fication, rhombic crystals. 

Experiment 2. — Preparation of Red or Mercuric Iodide by 
Precipitation. — To a few drops of a solution of a mercuric salt 
(corrosive sublimate, for example) add solution of potassium 
iodide, drop by drop ; a precipitate of mercuric iodide forms, 
and at first redissolves in the excess of the mercuric salt, but 
is permanent when sufficient iodide has been added. Continue 
the addition of potassium iodide ; the precipitate is redissolved, 
with formation of potassium mercuric iodide, KHgL. 

HgCl, + 2KI = Hgl, + 2KC1 

Mercuric chloride Potassium iodide Mercuric iodide Potassium chloride 

Hgl, + KI = KHgl, 

Mercuric iodide Potassium iodide Potassium mercuric iodide 

Notes. — When first precipitated, mercuric iodide is yellowish- 
red, but soon changes to scarlet. Its solubility either in solution 
of the mercuric salt or in solution of potassium iodide renders the 
detection of a small quantity of a mercuric salt by means of potas- 
sium iodide, or a small quantity of an iodide by means of a mercuric 
solution, difficult, and hence lessens the value of the reaction as a 
test. But the reaction is important as the official method for the 
preparation of mercuric iodide {Hijdrargijri lodidum Rubruin, 
U. S. P.). Mercuric iodide made in this way has the same com- 
position as that prepared by direct combination of its elements. 
In making the preparation, the two salts must be used in tlie pro- 
portion of HgCl, (268.86) to 2Ki (= 829.52). The mercury in 
mercuric or mercurous iodide is set free, and sublimes in globules, 
on heating either powder Avith dried sodium carbonate in a tost- 



212 THE METALLIC RADICALS. 

tube; the iodine may be detected by digesting with sodium 
hydroxide solution, filtering, and to the solution of sodium iodide 
thus formed adding starch-paste, acidulating Avith dilute hydro- 
chloric or sulphuric acid, and adding a solution of a nitrite, when 
blue starch iodide results. Mercuric iodide is insoluble in water, 
slightly soluble in alcohol, tolerably soluble in ether. 

Mercurous and Mercuric Nitrates. 

Experiment 3. — Place a globule of mercury, about half 
the size of a pea, in a test-tube ; add twenty or thirty drops of 
nitric acid ; boil slowly until red fumes no longer form ; set 
aside. On cooling, if a globule of mercury still remains in 
the tube, crystals of mercurous nitrate separate, These may 
be dissolved in water slightly acidulated with nitric acid. 
The solution may be retained for subsequent analytical 
operations. 

3Hg -f 4HNO3 = 3HgN03 -f 2H,0 + NO 

Experiment 4. — Place mercury in excess of concentrated 
nitric acid, and warm the mixture ; mercuric nitrate is formed, 
and will be deposited in crystals as the solution cools. Or, 
to crystals of mercurous nitrate add nitric acid, and boil until 
red fumes are no longer evolved. Retain the product for a 
subsequent experiment. 

3Hg + 8HNO3 = SHgCNOg), + 2N0 + 4H.p 

Mercury Nitric acid Mercuric nitrate Nitric oxide Water 

When mercury and nitric acid are boiled together, mercurous 
nitrate is formed if the mercury be in excess, while mercuric 
nitrate is produced if the acid be in excess. 

Mercuric Oxy nitrates. — From the normal mercuric nitrate 
several oxynitrates may be obtained. Thus on merely evapora- 
ting a solution of mercuric nitrate, and cooling, crystals having the 
formula Hg20(N03)2,2H20 are deposited. The latter, by wash- 
ing with cold water, yield a yellow pulverulent oxy nitrate, 
Hg302(N03)2: mixed with lard, this has sometimes been used as 
an ointment. By prolonged treatment with water, the yellow 
oxynitrate eventually yields mercuric oxide. 

The official preparations of mercuric nitrate are Liquor Hydrar- 
gyri Nitratis and Unguentum Hydrargyri Nitr^atis. 

Mercurous and Mercuric Sulphates. 

Experiment 5. — Boil two or three grains of mercury with a 
few drops of concentrated sulphuric acid in a test-tube or 
small dish, in a fume-cupboard ; sulphurous anhydride is 



HgSO. 


+ SO, + 


2HP 


Mercuric 


Sulphurous 


Water 


sulphate 


anhydride 





MERCURY. 213 

evolved, and mercuric sulphate, HgSO^ a white, heavy, 
crystalline powder results. 

Hg + 2H,S0, : 

Mercury Sulphuric 

acid 

Between two and three ounces of mercuric sulphate may 
be prepared from a fluid drachm of mercury and a fluid 
ounce of sulphuric acid boiled together in a small dish. The 
operation is completed and any excess of acid removed by 
cautiously evaporating the mixture of metal and liquid to 
dryness, in a fume-cupboard (sulphuric acid vapors beiug 
excessively irritating to the mucuous membrane of the nose 
and throat); dry crystalline mercuric sulphate remains. If 
residual particles of mercury are observed, the mass should 
be moistened with sulphuric acid and again carefully heated. 

By-products. — In chemical manufactories, secondary products, 
such as the sulphurous anhydride of the above reaction, are 
termed by-products, and, if of value, are utilized, In the present 
case the gas is of no immediate use, and is therefore allowed to 
escape. When very pure sulphurous anhydride is required for 
experiments on the small scale, this would be the best method of 
making it, a delivery-tube being adapted by means of a cork to 
the mouth of a flask containing the acid and metal. 

Mercuric Oxy sulphate. — Water decomposes mercuric sulphate 
into a soluble acid salt and an insoluble yellow oxysulphate, 
Hg^O^SO^. The latter is called Turpeth mineral, from its resem- 
blance in color to vegetable turpeth, the powdered root of Ipomcea 
turpethum, an Indian substitute for jalap. 

Experiment 6. — Rub a portion of the dry mercuric sulphate 
of the preceding experiment with as much mercury as it 
already contains ; the product, when the two have completely 
combined, is mercurous sulphate, Hg.^SO^ : it may be retained 
for a subsequent experiment. The exact proportion of 
mercury to mercuric sulphate is merely a matter of calcula- 
tion based upon the equation representing the chemical change 
which takes place. 

HgSO. + Hg = Hg,SO, 

Mercurous and Mercuric Chlorides. 

Experiment 7. — Mix thoroughly a few grains of dry mer- 
curic sulphate with about four-fifths of its weight of sodium 
chloride, and heat the mixture, slowly, in a test-lube in a 



214 



THE METALLIC RADICALS. 



Fig. 36. 



fume-cupboard ; mercuric chloride, HgCl2, or corrosive subli- 
mate, bichloride or perchloride of mercury (Hydrargyri 
Chloridum Corrosivum, U. S. P.), sublimes and condenses in 
the upper part of the tube in heavy colorless crystals. 

Somewhat larger quantities (in the proportion of 20 of 
mercuric sulphate to 16 of sodium chloride and, vide infra, 1 
of black magnese oxide) may be sublimed in a pair of two- 
ounce or three-ounce round-bottomed gallipots, the one 
inverted over the other, and the joint luted by means of 
moist fireclay (the powdered clay kneaded with water to the 
consistence of dough). The luting 
having been allowed to dry (some- 
what slowly to avoid cracks), the 
pots are placed upright on a sand- 
bath, sand piled round the lower 
and a portion of the upper pot, 
and the whole heated over the 
flame of a good Buusen burner for 
an hour or more in a fume-cupboard 
{see Fig. 36 — in which the pots are 
represented as raised in order to 
show the joint). Mercuric iodide, 
and calomel, may be sublimed in 
the same way. The temperature 
required for the former is some- 
what lower than that for corrosive sublimate while that for 
the latter is hio;her. 




Sublimation. 



HgSO. 


+ 


2NaCl = 


= HgCl, 


+ 


Na.,SO, 


Mercuric 




Sodium 


Mercuric 




Sodium 


sulphate 




chloride 


chloride 




sulphate 



Note. — If the mercuric sulphate contains any mercurous sul- 
phate, some calomel may be formed. This result will be avoided 
if 2 or 3 percent, of black manganese oxide be previously mixed 
with the ingredients. The action of this oxide is to turn out from 
the excess of sodium chloride used in the process the chlorine 
necessaiy to convert any calomel into corrosive sublimate, sodium 
manganate and a lower manganese oxide being simultaneously 
produced. 

Precaution. — The operation must be conducted with care in a 
fume-cupboard, because the vapor of corrosive sublimate, which 
might possibly escape, is very acrid and highly poisonous. Mercuric 
chloride volatilizes, though extremely slowly and slightly, at the 
ordinary temperature of warm weather. 

Unless preserved in an amber-colored bottle, a very dilute 



MERCURY. 215 

aqueous solution of mercuric chloride, when long kept, is liable to 
decomposition, calomel being precipitated, water decomposed, 
hydrochloric acid formed, and oxygen evolved. 

Experiment 8. — Mix a few grains of the mercurous sulphate 
from experiment 6 with about a third of its weight of sodium 
chloride, and sublime in a test-tube ; crystalline mercurous 
chloride, HgCl, or calomel {Hydrargyri Chloridum Mite, 
U. S. P.) results. Larger quantities may be prepared in the 
manner directed for corrosive sublimate, a somewhat higher 
temperature being employed : similar precautions must also be 
observed. 



Hg^SO, 


+ 


2NaCl = 


= 2HgCl + 


Na^SO, 


Mercurous 




Sodium 


Mercurous 


Sodium 


sulphate 




chloride 


chloride 


sulphate 



Calomel may also be made by other methods. The name calomel 
{Kalog, kalos, good, and /^elag, melas, black) was probably indica- 
tive of the esteem in which black mercuric sulphide (the compound 
to which the name calomel was first applied) was held. 

Test for corrosive sublimate in calomel. — If the mercurous sul- 
phate employed in this experiment contain mercuric sulphate, 
some mercuric chloride will also be formed. Corrosive sublimate 
is soluble in water, calomel insoluble ; the presence of the former 
may therefore be proved by boiling a few grains of the calomel in 
distilled water, filtering and testingby means of hydrogen sulphide 
or ammonium hydrosulphide as described hereafter. Or two or 
three grains of the suspected calomel may be mixed with a drop 
of 10 percent, alcoholic soap solution and a drop of freshly pre- 
pared alcoholic solution of guaiacum resin, and the mixture well 
stirred with 2 Oc. of ether. On evaporating the ethereal solution, 
the presence of mercuric chloride is indicated by an intense green 
coloration. If corrosive sublimate be present, the whole bulk of 
the calomel must be washed with hot distilled water till the filtrate 
ceases to give any indications of the impurity. Corrosive subli- 
mate is more soluble in alcohol, and still more in ether, than it is 
in water, while calomel is insoluble in all three. Ether in which 
calomel has been digested should therefore, after filtration, yield 
no residue on evaporation. Calomel is converted by hydrocyanic 
acid into mercuric cyanide and a black powder readily yielding- 
metallic mercury. Powell and Bayne have shown that a certain 
proportion of hydrochloric acid arrests this action. 

Note. — Carefully purified cotton, bleached by dilute bleaching- 
powder solution and thoroughly washed, takes up mercury from 
dilute solutions of mercuric chloride, leaving the solution rela- 
tively richer in chlorine; part of the mercury so taken up exists as 
unchanged mercuric chloride, part as mercurous chloride, and 
part as mercuric oxide. Hence, solutions of mercuric chloride 
should not be filtered through cotton wool. 



216 THE METALLIC RADICALS, 

Mercuric Oxide. 

Experiment 9. — Evaporate to dryness, in a small dish in a 
fume-cupboard, the mercuric nitrate from experiment 3 and 
heat the residue till no more nitrous fumes are evolved ; red 
mercuric oxide, HgO, red precipitate (^Hydrargyri Oxidum 
Ruhrum, U. S. P.) remains. 

2Hg(N0,), = 2HgO + 4N0, + O, 

Mercuric nitrate Mercuric oxide Nitrogen peroxide Oxygen 

A much larger yield of mercuric oxide (for the same quantity 
of nitric acid used to dissolve mercury) may be obtained by heating 
mercurous nitrate, or by thoroughly mixing with the dry mercuric 
nitrate from experiment 4 (prior to heating it) as much mercury as 
it already contains (ascertained by calculation from the atomic 
weights and the weight of mercuric nitrate employed, as in making 
mercurous sulphate). In this case the free mercury is also con- 
verted into mercuric oxide. 

HglNO^), + Hg - 2HgO -f 2N0, 
Mercuric nitrate Mercury Mercuric oxide Nitrogen peroxide 

Mercuric oxide is tested for nitrate by heating a little of the 
sample in a test-tube, when orange nitrous vapors are produced 
and are visible in the upper part of the tube, if nitrate be present. 

Mercuric oxide is an orange-red or red poAvder, more or less crys- 
talline according to the extent to which it may have been stirred 
during preparation from the nitrate. Unguentum Hydrargyri 
O.vidi Bubi, is official. Mercuric oxide, in contact with oxidizable 
organic matter, is liable to reduction to black or mercurous oxide. 

The earliest mode of preparing mercuric oxide consisted in main- 
taining mercury at a temperature near its boiling-point for many 
days in vessels, nearly closed to the air, in which a large surface 
of the metal was exposed. A red powder, which was Q?A\e6.precipi- 
taturn per se, was gradually formed. It was from mercuric oxide 
so prepared that Priestly first obtained oxygen. 

Experiment 10. — To solution of potassium or sodium hydrox- 
ide, or to lime-water, in a test-tube or a larger vessel, add solu- 
tion of corrosive sublimate, mercuric nitrate, or almost any 
other mercuric salt (but not mercuric cyanide) ; yellow mer- 
curic oxide, HgO (^Hydrargyri Oxidum Flavum, U. S. P.) is 
precipitated. 

HgClj, + Ca(OH), = HgO + CaCl, + H.O 

Mercuric Calcium Mercuric Calcium Water 

chloride hydroxide oxide chloride 

The precipitate only differs physically from red mercuric oxide ; 
the yellow oxide is more minutely divided than red. Unguentum 
Hydrargyri Oxidi Flari, is official. 



MERCURY. 217 

Mercurous Oxide. 

Experiment 11. — To calomel add solution of potassium or 
sodium hydroxide, or lime-water ; black mercurous oxide, 
HggO, is produced, and may be filtered off, washed and dried. 



2HgCl 


+ 


Ca(0H)2 


= Hg,0 


+ CaCl, 


+ H,0 


Merciirous 




Calcium 


Mercurous 


Calcium 


Water 


chloride 




hydroxide 


oxide 


chloride 





This reaction and the formation of a white curdy precipi- 
tate on the addition of solution of silver nitrate to the filtrate 
from the mercurous oxide, acidulated by nitric acid, form 
sufficient evidence that a powder consists of or contains calo- 
mel. The curdy precipitate is silver chloride. 

Analytical Reactions of Mercury Comjjounds. 

The Copper Test (for Mercurous or Mercuric Salts). — Place 
.a small piece of a bright copper, about half an inch long and ^ 

a quarter of an inch broad, in a solution of any salt of mer- | 

cury, mercurous or mercuric, and heat in a test-tube, the cop- 
per becomes coated with mercury, in a fine state of division. '' 
(The absence of any notable quantity of nitric acid, must be 
ensured, or the whole of the copper will be dissolved. Pour \^ 
away the supernatant liquid from the copper, wash the latter [ 
in the tube once or twice with water, remove the metal, dry it | 
by gentle pressure in a piece of filter-paper, place it in a dry, 
narrow test-tube, and heat it to redness in a Bunsen flame, the 
tube being held in an almost horizontal position ; the mercury 
volatilizes and condenses as a wdiitish sublimate of minute glob- 
ules on the cool part of the tube. The globules aggregate on 
being gently pressed with a glass rod, and are especially visible 
where flattened between the rod and the side of the test-tube. 

Notes on the test. — This is a valuble test for several reasons: — 
It is very delicate when performed with care. It seperates from 
the substance under examination, mercury itself, an element which, 
from its metallic lustre and fluidity, cannot be mistaken for any 
other. It is applicable to both mercurous and mercuric salts. 
It renders possible the detection of mercury in the presence of most 
other substances, organic or inorganic. 

In performing the test, the presence of any considerable quantity 
of nitric acid may be avoided by adding an alkali until a slight per- 
manent precipitate appears, and then very sliohtly reacidifying 
with a drop or two of acetic acid ; or by concentrating in an 
evaporating-dish after adding a little sulphuric acid and then 
rediluting. 



218 THE METALLIC RADICALS. 

Analytical Beactions of Mercuric Salts. 

1. To a few drops of a solution of a mercuric salt (coiTosive 
sublimate, for example; add solution of potassium iodide, drop 
bv drop; a yellowish-red precipitate of mercuric iodide, Hgl^, 
forms, and at first redissolves, but is permanent when suffi- 
cient potassium iodide has been added. Continue the addition 
of potassium iodide ; the precipitate is redissolved. {See 
notes on p. 211.) 

Aininoniated Mercury. 

2. Add a solution of a mercuric salt to ammonia water, 
taking care that the mixture, after well stirring, still smells 
of ammonia ; a white precipitate is produced. 

Performed in a test-tube, this reaction is a very delicate test for 
the presence of a mercuric salt; performed in larger yessels, the 
mercuric salt being corrosive sublimate, it is the process for the 
preparation of u-hife precipitate, formerly called ammonio-choride 
of mercury, now known as Ammoniated Mercury {Hydrargyrum 
Ammoniatirm, U. S. P.). 



HgCl - 


- 2XH.. = 


XHoHgCl 


- XH^Cl 


Mercuric 


Ammouia 


White 


Ammonium 


chloride 




precipitate 


chloride 



This precipitate is considered to be mercuri-ammonium chloride, 
XHoHgCl, — that is, ammonium chloride, XH^Cl, in which two 
atoms of hydrogen are replaced by one atom of mercury*. AVhen 
warmed with potassium hydroxide it evolves ammonia. 

Varieties of Ammoniated Mercury. — If the order of mixing the 
solutions in reaction 2 be reversed, and ammonia be added to solu- 
tion of mercuric chloride, a double mercuri-ammonium and mer- 
curic chloride, XH^HgCl.HgCl.,, is produced: it contains 76.57 
percent, of mercury. A double mercuri-ammonium and ammo- 
nium chloride, XH.,HgCl,yH^Cl, containing 65.57 percent, of 
mercmy made by adding caustic potash or caustic soda to a solu- 
tion of equal parts of corrosive sublimate and sal-ammoniac, is 
known as ^fusible white precipitate," because at a temperature 
somewhat below redness it fuses and then volatilizes. The official 
white precipitate contains theoretically, 79. 52 percent, of mercmy. 
An ointment ])repared ^^•ith this compound is official ( Vnguentum 
Hydrargyri Ammoniati. IT. S. P.). Prolonged washing ^ith water 
converts white precipitate into a yellowish compound (XH.HgCl, 
HgO); hence the official preparation is not thoroughly freed from 
the ammonium chloride which is formed during its manufacture, 
but which, if present in larger proportion than 7 or 8 percent., 
gives to it the character of partial or complete fusibility. The 



MERCURY. 



219 



officially recognized ammoiiiated mercury should volatilize at a 
temperature below redness without fusing, and should yield 78 to 
79 percent, of metallic mercury. With iodine, chlorine, or 
bromine, white precipitate may yield the dangerously explosive 
nitrogen iodide, chloride, or bromide. 

Dimercuri-ammonium iodide, NHg^I, is formed in testing for 
ammonia by means of Nessler's reagent (which see). 

3. Pass hydrogen sulphide through a mercuric solution 
until the liquid smells strongly of the gas; a black precipi- 
tate of mercuric sulphide, HgS, is produced. 



HgCl, 


+ H^S 


= 2HC1 + HgS 


Mercuric 


Hydrogen 


Hydorchloric Mercuric 


chloride 


sulphide 


acid sulphide 



Mercuric sulphide does not dissolve in dilute acids or in 
ammonium hydrosulphide. In the case of mercuric chloride 
(or of other mercuric salt to which hydrochloric acid has been 
added previously), hydrogen sulphide, when added in small 
quantity, produces a white precipitate. On the addition of 
more of the reagent, the color of the precipitate changes 
through various shades of yellow, orange, and brown, to black. 
The same white substance may also be obtained by heating a 
small quantity of black mercuric sulphide with solution of 
mercuric chloride. Its composition is represented by the 
forrnula, HgCl2, 2HgS. The yellow, orange, and brown sub- 
stances are intermediate in composition between this and mer- 
curic sulphide. 

Note. — Hydrogen sulphide also yields a black precipitate with 
solutions of mercurous salts. In the case of these salts, the pre- 
cipitate consists of a mixture of mercuric sulphide and mercury 
(not of mercurous sulphide); hence this reagent does not distin- 
guish between mercurous and mercuric salts. But in the course 
of systematic analysis, mercuric salts are precipitated from their 
solutions, as sulphide, after mercurous salts have been removed 
as chloride. 

Red Mercuric Sulphide. — Prolonged contact with hydrogen sul- 
phide or a hydrosulphide, especially if warm, converts the black 
into a red sulphide. Vermilion is mercuric sulphide prepared by 
sublimation. 

Ethiop's Mineral, formerly known as ffi/drargi/l SulphNrefKni 
cum S'ulphure, is a mixture of mercuric sulphide and sulphur, 
obtained by triturating the elements in a mortar till gh)buk^s of 
mercury are no longer visible. Its name is probably in allusion 
to its color. 



220 THE METALLIC RADICALS. 

Analytical Reactions of Mercurous Salts. 

1. To a solution of a mercurous salt (the mercurous nitrate 
obtained in experiment 2, for example) add hydrochloric acid 
or other soluble chloride ; a white precipitate of mercurous 
chloride, calomel, HgCl, is produced. 

2. To a solution of a mercurous salt add a few drops of a 
very dilute solution of potassium iodide; a yellow precipitate 
of mercurous iodide, Hgl, is produced. 



HgNO, 


+ KI = 


KNO3 


+ Hgl 


Mercurous 


Potassium 


Potassium 


Mercurous 


nitrate 


iodide 


nitrate 


iodide 



Unless very dilute solution of potassium iodide is employed, it is 
difficult to obtain a pure yellow precipitate, a greenish mixture of 
mercurous iodide and mercury being generally formed, owing to 
the decomposition of some of the former by excess of potassium 
iodide ; a considerable excess completely decomposes the mer- 
curous iodide, forming potassium mercuric iodide and mercury. 

2HgI + KI = KHgl3 + Hg 

The potassium mercuric iodide is soluble in water, and forms a 
nearly colorless solution, while the metallic mercury remains as a 
black percipitate. 

3. To a mercurous salt, dissolved or undissoloved (e. g., 
calomel), add ammonia water ; a black mercuros-ammonium 
salt (e. g., chloride, NH^Hg^Cl), is formed. It seems probable 
that the so-called mercuros-ammonium salts are really mix- 
tures of the mercuri-ammonium compounds {see p. 218) with 
metallic mercury. 

Other Tests for Mercury Co^npounds. 

The elimination of mercury in the actual state of metal by 
the copper test, coupled with the production or non-production of 
a white precipitate on the addition of hydrochloric acid to the 
original solution, is usually sufficient evidence of the presence 
of mercury and of its existence as a mercurous or a mercuric 
salt. But other tests may sometimes be applied with advan- 
tage. Thus metallic mercury is deposited on placing a drop 
of the solution on a gold coin and touching the drop and 
the edge of the coin simultaneously with a key : an electric 
current passes, under these circumstances, from the gold to 
the key, and thence through the liquid to the gold, decom- 
posing the salt, the mercury of which forms a white metallic 



MERCURY, 



221 



spot on the gold. This is called the galvanic test, and is useful 
for clinical purposes. — Solution of stannous chloride, SnCl.^, 
from the readiness with which it forms stannic chloride, SnCl^, 
gives with mercuric solutions a white precipitate of mercurous 
chloride, and rapidly reduces this mercurous chloride still 
further to a grayish mass of finely divided mercury; this is 
the magpie test, probably so-called from the white and gray 
appearance of the precipitate. The reaction may also be 
obtained from even such insoluble mercury compounds as 
white precipitate, — A confirmatory test for mercuric and 
mercurous salts will be found in the action of solution of 
potassium, sodium, or calcium hydroxide. {See pp, 216, 217.) 
— Potassium chromate, K^CrO^, gives with mercurous salts, 
a red percipitate of mercurous chromate, HggCrO^. — Mer- 
cury and all its compounds are more or less completely vola- 
tilized when heated in a dry tube, many of the latter being 
decomposed and yielding globules of metallic mercury,— 
All dry compounds of mercury are decomposed when heated 
in a dry test-tube with dried sodium carbonate, mercury sub- 
liming and condensing in visible globules, or as a whitish 
deposit which yields globules when rubbed with a glass rod. 

Antidote. — Albumin gives a white precipitate with solu- 
tions of mercuric salts ; hence the importance of administering 
white of Qgg, while waiting for a stomach-pump or stomach- 
siphon, in case of poisoning by corrosive sublimate. 



QUESTIONS AND EXERCISES. 

Name the chief ore of mercury, and describe a process for the extrac- 
tion of the metal.— Give the properties of mercury. — In what state does 
mercury exist in " Gray Powder "?— What other preparations of metallic 
mercury itself are employed in medicine ? — State the relation of the 
mercurous to the mercuric compounds. — Distinguish between an alloy 
and an amalgam. — State the formulae of the two mercury iodides. — Under 
what circumstances has mercuric iodide different colors ? — Illustrate the 
chemical law of Multiple Proportions as explained by the atomic theory, 
employing for that purpose the stated composition of the two mercury 
iodides. — Write down the formulae of Mercurous and Mercuric Nitrates 
and Sulphates. — How is Mercuric Sulphate prepared ?— What is the 
formula of " Turpeth Mineral"? — Describe the processes necessary for 
the conversion of mercury into Calomel and Corrosive Sublimate, using 
equations. — Why is black maganese oxide sometimes mixed with the 
other ingredients in the preparation of corrosive sublimate? — Give the 
chemical and physical points of difterence between calomel and corrosive 
sublimate. — How may calomel in corrosive sublimate be detected ? — 
Calculate how much Mercury will be required in the manufacture of one 
ton of Calomel. Ans. 17 cwt. nearly. — ^Mention the otticial preparations 
of the Mercury Chloride. — Give the formubv and mode of formation 



222 THE METALLIC RADICALS. 

of the Eed, Yellow, and Black Mercury Oxides, employing diagrams. — 
Explain the action of the chief general test for Mercury. — How are 
mercurous and mercuric salts analytically distinguished? — Give a proha- 
bie view of the constitution of Hydrargyrum Ainrnoniatum, U- S. P., and 
an equation showing how it is made. — State the best temporary antidote 
to poisoning by mercur}'. 



LEAD: Pb. Atomic weight, 205.35. 

Occurrence. — The ores of lead are numerous; but the one from 
■\vhieh the metal is chiefly obtained is lead sulphide, PbS, galena 
(from ^icO.rivri, gal'ene, tranquility, perhaps from its supposed efiect 
in allaying pain.) 

Preparation. — The ore is first roasted in a current of air; much 
sulphur is thus burnt off as sulphurous anhydride, while some of 
the metal is converted into oxide; a portion of the suliDhide is at 
the same time oxidized to suljohate. Oxidation is then stopped and 
the temperature raised, whereupon the oxide and sulphate, inter- 
acting with undecomposed sulphide, yield the metal and sulphur- 
ous anhvdride: — 2PbO-PbS=3Pb-SO.,; and PbSO,-PbS= 
2Pb-f-2Sb,. 

Uses. — The uses of lead for making pipes and lead sheeting 
are well known. Alloyed with some arsenic, it is used in making 
ordinary sAo^/ with tin it forms solder; with antimony and tin, 
type-metal; and in smaller quantities it enters into the composition 
of Britannia metal, pjeuier, and other alloys. Lead is so slightly 
attacked by many dilute acids that chemical vessels and instru- 
ments are sometimes made of it. Hot hydrochloric acid slowly 
converts it into lead chloride with evolution of hydrogen. Cold 
sulj^huric acid in presence of air only very slightly attacks it with 
formation of lead sulphate and water; hot concentrated sulphuric 
acid attacks it rapidly with formation of )ead sulphate and evolu- 
tion of sulphurous anhydride. Hot nitric acid converts it into 
lead nitrate with evolution of nitric oxide. 

The lead salts used in pharmacy and all other lead preparations 
are obtained, directly or indirectly, from the metal itself. Heated 
to a high temperature in a current of air, lead combines with 
oxygen and forms lead oxide, PbO, a yellow powder (massicot), or, 
if fused and solidified, a brighter, reddish-yellow, heavy mass of 
bright scales {Plumbi Oxidum, V. S. P.), termed litharge (from 
7Jdoc, lithos, a stone, and apyvpoc, arguros, silver). It is from this 
oxide that the chief lead compounds are obtained. Lead oxide, 
by further heating in a current of air, at a temperature considerably 
below that at which it was produced, yields red lead or minium, 
Vh.f)^. The latter oxide is intermediate in composition betw-een 
lead oxide, PbO, and lead peroxide, PbO.,; and, although it is 
usually represented by the formula Pb.p_^, it is subject to some 
variation in composition. Both litharge and red lead are much 



LEAD. 223 

used by painters, paper-stainers and glass-manufacturers. White 
lead is lead hydroxy carbonate, 2PbCo3, Pb(0H)2; it is made by 
exposing lead, cast in spirals or little gratings, to the action of air, 
acetic acid fumes, and carbonic anhydride, the latter generated 
from decaying vegetable matter, such as spent tan: lead oxyacetate 
slowly but continuously forms, and is as continuously decom- 
posed by the carbonic anhydride, with production of hydroxy- 
carbonate, or dri/ white lead. Lead hydroxycarbonate is also 
also made by bringing carbonic anhydride and litharge together 
in a solution of lead acetate. Ground up with about 7 percent, 
of linseed-oil, it forms the white lead used by painters and 
plumbers. 

Lead compounds are poisonous, producing saturnine colic, and 
even paralysis. These effects are termed saturnine from an old 
name of lead, Saturn. The alchemists called lead Saturn, first, 
because they thought it the oldest of the seven then known metals, 
and it might therefore be compared to Saturn, who was regarded 
as the father of the gods; and, secondly, because its power of 
dissolving other metals recalled a peculiarity of Saturn, who was 
said to be in the habit of devouring his own children. 

Lead Acetate. 

Experiment 1. — Place a few grains of lead oxide in a test- 
tube, add about an equal weight of water and two and a half 
times its weight of acetic acid, and boil ; the oxide dissolves 
and forms a solution of lead acetate, Pb( 0211302)2. When 
cold, or on evaporation if much water has been used (the 
solution being kept faintly acid), crystals of lead acetate 
(Plumbi Acetas, U.S. P.), Pb(02H302)2, 3H2O, are deposited. 
Larger quantities are obtained by the same method. 

PbO + 2H02H,02 = Pb(02H302)2 + H2O 

Lead oxide Acetic acid Lead acetate Water 

The salt is termed Sugar of Lead, from its sweet taste. 

Lead Subacetate or Oxyacetate. 

Experiment 2. — Boil lead acetate with four times its weight 
of water and rather less than two-thirds of its weight of lead 
oxide ; the filtered liquor is solution of lead subacetate, 
Liquor Plumhi Subacetatis, U. S. P., Goulard's Extract. It 
should contain 25 percent, of lead subacetate Pb2O(02H3O,)2. 

A similar solution was used by M. Goulard, who drew attention 
to it in 1770 and called it Extractum Saturni. A more dilute 
solution, 1 of Liquor in M of distilled water, is also official under 



224 THE METALLIC RADICALS. 

the name of Liquor Plumbi Subacetatis Dilutus. The latter is 
commonly known as Goulard water. Ceratum Plumbi Subacetatis, 
a modification of the original Goulard^ s Cerate, is official. 

Lead Nitrate. 

Experiment 3. — Digest a few grains of led lead in dilute 
nitric acid ; lead nitrate, Pb(N03)2, is formed, and remains in 
solution, while lead peroxide, PbO,^, remains behind as a 
dark brownish-purple powder. Lead Nitrate may be made 
more directly by dissolving litharge, PbO, in nitric acid. 
PbO+2HN03=Pb(N03),+H,0. 

Lead nitrate or acetate is used in preparing lead iodide. For 
this purpose the above mixture may be filtered, the lead peroxide 
washed with hot water, the filtrate and washings evaporated to dry- 
ness to remove excess of nitric acid, the residual lead nitrate redis- 
solved by boiling with a small quantity of hot water, and the solu- 
tion set aside to crystallize; or a portion may at once be used for 
the next experiment. Lead nitrate, Plumbi Nit r as, U. S. P., forms 
white crystals derived from octahedra. 

Lead peroxide, PbOg, when heated with concentrated hydro- 
chloric acid vields lead chloride, PbCl.^, chlorine, and water. 
PbO^ + 4HCi = PbCl^ + CI2 + 2H2O. 

Lead Iodide. 

Experiment 4. — To a neutral solution of lead nitrate add 
solution of potassium iodide; a precipitate of lead iodide, Pbig 
(Plumbi lodidum, U. S. P.), is produced. Equal weights of 
the salts may be used in making large quantities. 

Pb(N03), + 2KI = Pbl, + 2KNO3 

Lead nitrate Potassium iodide Lead iodide Potassium nitrate 

Heat the lead iodide with the supernatant liquid, and filter if 
necessary ; the salt dissolves, and separates again in golden 
crystalline scales as the solution cools. 

Lead iodide is soluble in solution of ammonium chloride. 

Lead Oleate. 

Experiment 5. — Boil together in a small porcelain dish a 
few grains of a very finely powdered lead oxide, with twice 
its weight of olive-oil, and also two or three times its weight 
of water, w^ell stirring the mixture, and from time to time 
replacing water that has evaporated; the product is a white mass 
of lead oleate, Pb(CjgH3302)2J glycerin remaining in solution. 



LEAD. 225 

3PbO + 3H,0 + 2C3H5(C,3H330,)3 
Lead oxide Water Glyceril oleate (olive-oil or oleine) 

3Pb(C,3H330,), 4- 2C3H,(OH)3 

Lead oleate (lead plaster) Glyceryl hydroxide (glycerin) 

This action between the lead oxide and olive-oil is slow, requiring 
several hours for its completion. 

Lead Plaster {Emplastrimi Plumbi, U. S. P.) consists of practi- 
cally pure lead oleate prepared by the interaction of lead acetate 
with solution of soap (made from olive-oil). 

Modes of formation of Chloride, Sulphide, Chromate, Sulphate, 
Hydroxide, and other lead compounds are incidentally described in 
the following analytical paragraphs. 

Analytical Reactions of Lead Salts. 

1. To a solution of a lead salt (acetate, for example) add 
hydrochloric acid; a white precipitate of lead chloride, PbClg, 
is obtained. Boil the precipitate with a moderate quantity of 
water ; it dissolves, but is redeposited in small acicular crystals 
when the solution cools. Filter the cold solution, and pass 
hydrogen sulphide through it; the formation of a black pre- 
cipitate of lead sulphide, PbS, shows that the lead chloride is 
soluble to a slight extent in cold water. 

Note. — The formation of a white precipitate (soluble in hot 
water and blackened by hydrogen sulphide) on the addition of 
hydrochloric acid, sufficiently distinguishes lead salts from those 
of other metals; but the non-production of such a precipitate does 
not prove the absence of a small quantity of lead since chloride is 
slightly soluble in water. 

2. Through a dilute solution of a lead salt, acidulated with 
hydrochloric acid, pass hydrogen sulphide; a black precipitate 
of lead sulphide, PbS, is produced. 

Lead in Water. — The foregoing is a very delicate test. Should 
a trace of lead be jDresent in water used for drinking purposes, it 
may be detected by means of hydrogen sulphide. On passing the 
gas through a pint of such (acidulated) water, a brownish color is 
produced. If the tint is scarcely perceptible, set the liquid aside 
for a day; the hydrogen sulphide will undergo oxidation and a 
thin layer of sulphur will be found at the bottom of the vessel, 
white if no lead sulphate be present in it, but more or less brown 
if it contain lead sulphide. Hygienists regard one-twentieth of a 
grain of lead per gallon as dangerous, while a smaller quantity may 
do harm. Water commonly used for drinking purposes should 
not contain a trace. 
15 



226 THE METALLIC RADICALS. 

8. To a solution of a lead salt add ammonium hydrosul- 
phide ; a black precipitate of lead sulphide, insoluble in 
excess ; is produced. 

4. To a solution of lead salt add solution of potassium 
chromate, K^CrO^, ; a yellow precipitate of lead chromate, 
PbCrO^, is formed, insoluble in dilute acids and in solution of 
ammonium chloride. 

Chromes. — This reaction has technical as well as analytical 
interest. The precipitate is the common pigment termed chrome 
yellow^ or lemon chrome. Boiled with slaked lime and water, a 
portion of the chromium is remoyed, together with oxygen, and 
forms calcium chromate, while lead oxy chromate, of a bright 
orange-red color [chrome orange) is also produced. 2PbCrO^ + 
Ca(0H)2 = CaCrO, + Pb^OCrO, + H^O. 

5. To a solution of a lead salt add dilute sulphuric acid, or 
a solution of a sulphate; a white precipitate of a lead sulphate, 
PbSO^, is produced. 

Lead sulphate is slightly soluble in concentrated acids, and in 
solutions of some potassium and sodium salts; it is insoluble in 
acetic acid. It is readily dissolved by solution of ammonium ace- 
tate, the resulting liquid yielding the ordinary reactions with 
soluble chromates and iodides. It also dissolves readily in solution 
of ammonium tartrate in presence of ammonia. 

In dilute solutions the above reaction with sulphuric acid or a 
soluble sulphate does not take place immediately; the precipitate, 
however, is produced after a time; its formation may be hastened 
by evaporating the mixture nearly to dryness and then diluting, or 
by adding to the mixture its own volume of alcohol. 

The white precipitate often noticed in the vessels in which dilute 
commercial sulphuric acid is kept, is lead sulphate derived from 
the leaden chambers in which the acid is made. Its solubility in 
concentrated and its insolubility in dilute sulphuric acid explains 
its precipitation. 

Antidotes. — From the insolubility of lead sulphate in water, the 
best antidote, in a case of poisoning by the acetate or other soluble 
lead salt, is a soluble sulphate, such as Epsom salt, sodium sul- 
phate, or alum, vomiting also being induced, or the stomach- 
pump, or stomach-siphon, applied as quickly as possible. 

Other tests for lead will be found in the reactions with potas- 
sium iodide (see p. 224); with alkali-metal carbonates, which 
produce white hydroxycarbonate, 2PbC03, Ph(C>H).^, insoluble 
in excess ; with alkalies, which yield a white precipitate of lead 
hydroxide, Pb(OH)./), more or less soluble in excess, and 
with alkali-metal phosphates, arsenates, ferrocyanides, and 



BISMUTH. 227 

cyanides, which form compounds mostly insoluble, but of no 
special analytical interest. Insoluble salts of lead may be 
dissolved by solution of potassium hydroxide or sodium hydrox- 
ide, NaOH. 

The metal is precipitated in a beautifully crystalline state 
by introducing metallic zinc (and some other metals) into a 
solution of a lead salt; the lead-tree is thus formed. — Solid 
lead compounds are reduced when heated by the blowpipe- 
flame in a small cavity in a piece of charcoal, a soft, malleable 
bead of metal being produced, and a yellowish ring of lead 
oxide deposited on the charcoal. 



QUESTIONS AND EXEECISES. 

Write down equations representing the smelting of galena. — Mention 
some of the alloys of lead.— How is litharge produced? — Give the form- 
ulae of white lead and red lead. — Describe the manufacture of white lead. 
— Draw a diagram showing the formation of Lead Acetate. — Describe the 
preparation and composition of Liqtior Phimbi Suhacetatis, U, S. P. — What 
is the action of nitric acid on red lead litharge and lead? — Mention the 
chief tests for lead. — How would you search for soluble compounds of 
lead in a domestic water supply ? — What is the composition of chrome 
yellow and of chrome orange ? — ^Name the best antidote in cases of poison- 
ing by lead salts, and explain its mode of action. 



BISMUTH : Bi. Atomic weight, 206.9. 

Occurrence. — Bismuth occurs in the metallic state in nature. 
It is freed from adherent quartz, etc. , by simply heating, when the 
metal melts, runs off, and is collected in appropriate vessels. It 
is also met with in combination with other elements; most com- 
monly, as oxide, ^\0.^, in bismuth ochre ; sometimes, as sulphide, 
Bi^Sy, in bismuth glance. Bismuth is grayish white in color. In 
its general chemical relationships it is allied to the elements of the 
antimony and arsenic group, although in its analytical behavior 
it is more closely related to lead and copper. 

Purification. — Arsenic may be removed from melted bismuth 
by stirring it with an iron rod, iron arsenide rising to the surface 
of the mass: antimony by stirring in some bismuth oxide, when 
antimony oxide separates. Other metals present in bismuth, 
especially copper, are converted into sulphides, while bismuth is 
not affected, by fusing the crude metal with about five percent, of 
potassium cyanide, and two percent, of sulphur, tlie whole being 
well stirred for a quarter of an hour witli a clay rod (stem of a 
tobacco-pipe). On pouring off the metal from the flux, and 



THE METALLIC RADICALS. 

iiiiiii,^^^ and .^tirring it with five percent, of a mixture of potassium 
and sodium carbonates, suljDhur and traces of other impurities are 
removed, and the metal is obtained pure. — Tamm. 

Uses. — Beyond the employment of some of its compounds in 
medicine, bismuth is but little used. Melted bismuth expands 
considerably on solidifying, and hence is valuable in taking sharp 
impressions of dies. It is a constituent of some kinds of type- 
metal and of pewter-solder. 

Bismuth Nitrate. 

Experiment 1. — To a few drops of nitric acid and an equal 
quantity of water, iu a test-tube, add a small quantity of 
powdered bismuth, heating the mixture if necessary; nitric 
oxide, NO, escapes, aud solution of bismuth nitrate, 61(^03)3, 
results. 

Bi + 4HNO3 = ^1(^03)3 + NO + 2H2O 
Bismuth Nitric acid Bismuth nitrate Nitric oxide Water 

The solution, on evaporation, gives crystals, Bi(N03)3, 5H2O, 
any arsenic which the bismuth may have contained remaining in 
the mother-liquor. 

To make bismuth nitrate, oxynitrate, oxycarbonate (or other 
salts) on a larger scale, 2 ounces of the metal, in small fragments, 
are gradually added to a mixture of 4 fluid ounces of nitric acid 
and 3 of water, and, when effervescence (due to escape of nitric 
oxide) has ceased, the mixture is heated for ten minutes, poured 
off from any insoluble matter, evaporated to 2 fluid ounces to 
remove excess of acid, and then either set aside for crystals of 
nitrate to form, or poured into half a gallon of water to obtain 
bismuth oxynitrate, or into a solution of 6 ounces of ammonium 
carbonate in a quart of water to form oxycarbonate, as described 
in the following experiments. 

The precipitates should be washed with cold water and dried 
at a temperature not exceeding 150° F. (65.5° C). Exposed in 
the moist state to 212° F. (100° C.) for any considerable time, 
they undergo slight decomposition. 

Bismuth Subnitrate or Oxynitrate. 

Experiment 2. — Pour some of the above solution of bismuth 
nitrate into a considerable quantity of water; decomposition 
occurs, and a precipitate (of somewhat varying chemical com- 
position) consisting of bismuth oxynitrate and h3'droxy nitrate 
is produced ( Bi.wuitJd Subnitras, U. S. P.). The formation 
of bismuth oxynitrate is represented by the following 
equation : — 



BISMUTH. 



229 



Bi(N0,)3 - 
Bismuth nitrate 



Water 



= BiONO^ 4- 2HNO3 

Bismuth oxyiiitrate Nitric acid 



Filter, and test the filtrate for bismuth by adding excess of 
sodium carbonate; the formation of a precipitate shows that some 
bismuth still remains in solution. 

Decomposition of bismuth nitrate by water is the ordinary pro - 
cess for the preparation of bismuth oxynitrate for use in medicine. 
For this purpose the original metal must contain no arsenic. In 
manufacturing the compound, therefore, before pouring the solu- 
tion of nitrate into water, the liquid should be tested for arsenic 
by one of the hydrogen tests; if that element be present, the solu- 
tion must be evaporated, and only the deposited crystals be used 
in the preparation of the oxynitrate. This must be done because 
on pouring an arsenical solution of bismuth nitrate into water, the 
arsenic is not wholly removed in the supernatant liquid unless the 
oxynitrate be redissolved and reprecipitated several times, accord- 
ing to the amount of arsenic present. 

Bismuth subnitrate is gradually decomposed by solutions of 
alkali-metal carbonates (also by the bicarbonates, with production 
of carbonic anhydride), bismuth oxycarbonate and the alkali- 
metal nitrate being formed. 

Bismuth Oxy salts. — On pouring a solution of bismuth chloride, 
BiCl^, into water, bismuth oxychloride, BiOCl, is produced (a 
white powder used as a cosmetic, ''pearl-white" [Blanc de Perle), 
also in enamels and in some varieties of sealing-wax). Bismuth 
bromide, BiBr.^, and iodide, Bilg, similarly treated, yield oxy- 
bromide, BiOBr, and oxyiodide, BiOI. The subnitrate is, there- 
fore, probably an analogous compound, an oxynitrate, BiONOg. 
Bismuth sulphate, Bi2(S0^).^, is also decomposed when placed in 
water, giving bismuth oxysulphate, Bi202SO^. 

It is difficult to prove whether or not the water in hydrous bis- 
muth oxynitrate, BiON03,H20, is an integral part of the salt. If 
it is, the compound is probably bismuth hydroxynitrate, 
Bi(OH)2N03. 

Bismuth Oxide. 

Experiment 3. — Boil bismuth subnitrate with solution of 
sodium hydroxide for a few minutes ; it is converted into 
yellowish bismuth oxide, Bi.^O^. 



2BiON03 + 2NaOH = "Bifi, + 2NaN0, + H^.O 

Bismuth Sodium Bismuth Sodium Wa'ter 

oxynitrate hydroxide oxide nitrate 



230 THE METALLIC RADICALS. 

Bismuth Subcarbonate or Oxycarbonate. 

Experiment 4. — To a solution of bismuth nitrate add solu- 
tion of ammonium carbonate ; a white precipitate of hydrous 
bismuth oxycarbonate, (Bismuthi Subcarbonas, U. S. P.), is 
produced, of somewhat varying composition, but approximating 
to the formula, 2Bifi.fiO.^, iifi, 

2Bi(NO,)3+2K,H,,CA+H,0 = 6NH,N0,+ Bip,C03+ 300^ 

Bismuth " Ammonium Ammonium Bismuth Carbonic 

nitrate carbonate " nitrate oxycarbonate anhydride 

This compound may be regarded as similar in constitution to 
the oxysalts just described which are commonly looked upon as 
salts of a hypothetical radical bismuthyl (BiO). 

Bismuth Citrate. 

Experiment 5. — Heat 4 parts of Bismuth Subnitrate and 3 
parts of citric acid with 16 parts of water on a water-bath, 
with frequent stirring, until a drop of the mixture yields a 
clear solution with ammonia water. Then add 200 parts of 
water. The precipitate, after thorough washing, and drying 
at a gentle heat, is Bismuth Citrate, BiCj.H.0., (Bismuthi 
Citras, U. S. P.). 

Experiment 6. — To bismuth citrate, rubbed into a smooth 
paste with water, and heated on a water-bath, add ammonia 
water until the salt is dissolved and the liquid is neutral or 
only faintly, alkaline, and filter. The solution, evaporated 
to a syrupy consistance and spread on glass plates yields when 
dry. Bismuth and Ammonium Citrate, {Bismuthi et Ammonii 
Citras, U. S. P.) in scales. 

Bismuth Subsalicylate. 

Experiment 7. — To a solution of bismuth nitrate add a 
solution of sodium salicylate; a white precipitate of bismuth 
subsalicylate, CgH^.OH.COO.BiO (Bismidhi Subsalicylas, 
U. S. P.), is produced. 

Bismuth Subgallate. 

Experiment 8. — To a solution of 3 parts of crystallized bis- 
muth nitrate in 20 parts of dilute acetic acid (1 part of 
glacial acetic acid to 2^ parts greater) add a solution of 1 
part of gallic acid in 45 parts of water ; a bright yellow pre- 



BISMUTH. 

cipitate of bismuth subgallate (Bismuthi Subgallas, U. B. Ky, 
is obtained, which is of somewhat variable chemical composi- 
tion. 

Analytical Reactions of Bismuth Salts. 

1. Through a solution of a bismuth salt (a slightly acid 
solution of nitrate, for example) pass hydrogen sulphide ; a 
black precipitate of bismuth sulphide, Bi^S^, is produced. 
Add ammonia water (to neutralize the acid) and then ammo- 
nium hydrosulphide ; the precipitate, unlike AS2S3 and &h^8.^, 
is insoluble. 

2. Concentrate almost any acid solution of a bismuth salt 
and pour into much water containing some sodium or ammo- 
nium chloride; a white precipitate of bismuth oxychloride 
results. 

This reaction is characteristic of bismuth salts. Bismuth oxy- 
chloride is especially insoluble in water, and is distinguished from 
antimonious oxychloride by being insoluble in solution of tartaric 
acid. 

3. To a solution of a bismuth salt add caustic alkali ; a 
white precipitate of bismuth hydroxide, Bi(OH)^, is produced, 
insoluble in excess, and becoming yellowish on boiling. 

4. First prepare a reagent as follows : — Dissolve 1 grain of 
lead acetate in 3 ounces of hot water and add 30 drops of acetic 
acid ; dissolve 60 grains of potassium iodide in 3 ounces of 
water ; mix the solution ; on cooling, lead iodide is deposited 
in the characteristic yellow crystalline plates or scales. Next, 
place some of the reagent (crystals included) in a test-tube 
and heat gradually till solution takes place. Any liquid con- 
taining, or supposed to contain, bismuth is then added, and 
the whole allowed to cool. The separated scales will show a 
distinct change in color from the original yellow to dark orange 
or crimson, according to the quantity of bismuth present. 

Test for calcmm phosphate in bismuth salts. — Dissolve the 
powder in nitric acid add about twice its weight of citric acid 
and sufficient ammonia to give decided alkalinity ; then boil, 
keeping the mixture faintly alkaline with ammonia ; bismuth 
remains in solution, and calcium phosphate is precipitated. 

Tests for other impurities in bismuth or its salts. — Dissolve 
in nitric acid ; concentrate and set aside for crystals of bismuth 
nitrate to separate ; pour off the mother-liquor, which will con- 
tain any impurities in a concentrated form. If this mother- 



232 THE METALLIC RADICALS. 

liquor be evaporated with hydrochloric acid until all the 
uitric acid is dissipated, a little of the product should yield uo 
evidence of arsenic on being examined by Marsh's test ; no 
blue coloration on adding water and excess of ammonia (cop- 
per), and no precipitate on filtering and saturating theammo- 
niacal filtrate with nitric acid (silver); uo white precipitate 
with dilute sulphuric acid (lead); no red or black precipitate 
with sodium sulphide (tellurium or selenium); and uo blue 
precipitate with potassium ferrocyanide (iron). 

CADMIUM : Cd. Atomic Weight, 111.6. 

In most of its chemical relations cadmium resembles zinc. In 
nature it occurs chiefly as an occasional constituent of the ore of 
that metal. In distilling zinc containing cadmium, the latter, 
being the more volatile, passes over first. ' In analytical operations 
cadmium, unlike zinc, comes down among the metals precipitated 
by hydrogen sulphide ; that is, its sulphide is insoluble in highly 
dilute hydrochloric acid, while zinc sulphide is soluble. It is a 
white malleable metal which boils at 770° C. Sp. gr. ^.Q at 
15.5° C. 

Beyond the occasional employment of the sulphide as a pigment 
(jaune brill iant), and of the iodide and bromide in photography, 
cadmium and its salts are but little used. 

Cadmium Iodide. 

Experiment. — Digest together, in a flask, metallic cadmium, 
warm water, and iodine, until the color of the iodine disap- 
pears ; solution of cadmium iodide, Cdl^, remains. Glistening 
white crystalline scales may be obtained on evaporating the 
solution. 

This salt is employed with other iodides in iodizing collo- 
dion for photographic use. It readily melts ; and it is soluble 
in water or alcohol, the solution reddening litmus. 

Analytical Reactions of Cadmium Salts. 

1. Through a solution of a cadmium salt (Cdig or CdClg) 
pass hydrogen sulphide; a yellow precipitate of cadmium sul- 
phide, CdS, is produced, resembling in appearance arsenous, 
arsenic, and stannic sulphides. Add ammonium hydrosul- 
})hide ; the precipitate, unlike the sulphides just mentioned, 
does not dissolve. It dissolves easily in hot dilute hydrochloric 
or sulphuric acid. 



SILVER. 



233 



Cadmium and cupric sulphides may be separated by means of 
solution of potassium cyanide, in which cupric sulphide is soluble 
and cadmium sulphide insoluble. 

2. To a solution of a cadmium salt add solution of potas- 
sium hydroxide ; a white precipitate of cadmium hydroxide, 
Cd(0H)2, is produced, insoluble in excess of the precipitant. 

Zinc hydroxide, Zn(OH).^, precipitated under similar circum- 
stances, is soluble in solution of potassium hydroxide; the filtrate 
from the cadmium hydroxide may therefore be tested for any zinc, 
present as an impurity, by adding hydrogen sulphide or ammonium 
hydrosulphide. Zinc and cadmium hydroxides are soluble in 
excess of ammonia water. 

Before the blow-pipe fiame, on charcoal, cadmium salts give a 
brown deposit of cadmium oxide, CdO. 



QUESTIONS AND EXEECISES. 



How does bismuth occur in nature ? — What is the quantivalence of bis- 
muth ? — Write equations descriptive of the action of nitric acid on bis- 
muth, and water on bismuth nitrate. — How may arsenic be excluded from 
bismuth salts? — Give an equation illustrating the process for the prepara- 
tion of bismuth carbonate.— Mention the tests for bismuth. — In what con- 
dition does cadmium occur in natui-e ? — By what process may cadmium 
iodide be prepared ? — Mention the chief test for cadmium. — Distinguish 
cadmium sulphide from sulphides of similar color. — How is cadmium 
separated from zinc ? 



SILVER : Ag. Atomic weight, 107.12. 

Occurrence. — This element occurs in nature in the metallic state; 
and also combined with sulphur as silver sulphide, Ag.,S, asso- 
ciated with much lead sulphide, forming argeniiferous galena. 

Preparation. — The lead obtained from argentiferous galena is 
melted and slowly cooled; crystals of nearly pure lead separate 
first and are raked out from the still fluid mass, which thus con- 
sists of an alloy richer in silver. The operation is repeated several 
times until an alloy very rich in silver is finally obtained; this is 
roasted in a current of air, whereby the lead is oxidized and 
removed as litharge, while pure silver remains. Other ores undergo 
various preparatory treatments according to their nature, and are 
then shaken with mercury, which amalgamates with and dissolves 
the particles of metallic silver, the mercury being subsequently 



234 THE METALLIC RADICALS. 

removed from the amalgam by distillation. Soil and minerals con- 
taining metallic silver are also treated in this way. An important 
improvement in the amalgamation process, by which the mercury 
more readily unites with the silver, consists in the addition of a 
small proportion of sodium to the mercury. Silver chloride may 
be dissolved from ores by solution of sodium thiosulphate. 

Silver is not readily affected by the weak acid or other fluids of 
food, though it is rapidly tarnished by sulphur and many sulphur 
compounds. It does not perceptibly attack hydrochloric acid; it 
reduces somewhat diluted nitric acid to nitric oxide, NO, silver 
nitrate AgNOg, being formed; it also reduces hot sulphuric acid 
to sulphurous anhydride, SO.^, silver sulphate, Ag.^SO^, being 
formed. This latter salt is crystalline, and slightly soluble in 
water. 

Impure Silver Nitrate. 

Experiment 1. — Dissolve a silver coin in nitric acid; nitric 
oxide, NO, is evolved, and a solution of silver and cupric 
nitrates is obtained. 

Silver Coinage. — Pure silver is too soft for use as coin; it is 
therefore hardened by alloying with copper. The silver coinage 
of the United States contains 10 percent, of copper. British sil- 
ver money contains 7.5, German 25, and French 10 and 16.5 per- 
cent, of copper — for the fineness of the French standard silver is 
0. 900 in the five- franc piece, while an inferior alloy of 0. 835 is 
used for the coins of lower denominations. The one-franc piece, 
composed of the latter alloy, is still made to weight five grammes, 
the weight originally chosen for the franc as the unit of the mone- 
tary scale when the fineness of the coin was 0. 900. It has now 
become a token, of which the nominal value exceeds the intrinsic 
value. 

Silver Chloride. 

Experiment 2. — To the product obtained in the preceding 
experiment, add dilute hydrochloric acid or a solution of a 
chloride ; a white precipitate of silver chloride, AgCl, is pro- 
duced, copper still remaining in solution. Collect the precipi- 
tate on a filter and wash it w^ith water ; it is pure silver 
chloride. 

Notes. — The copper may also be separated by evaporating the 
solution of the metals in nitric acid to dryness and gently heating 
the residue, when the cupric nitrate is decomposed, but the silver 



SILVER. 



235 



nitrate is unaifected. The latter may be dissolved out from the 
residual cupric oxide by means of water. 

Silver chloride may be obtained in crystals by evaporation of 
its solution in ammonia water. 

The usefulness of halogen salts of silver in photography depends 
upon the fact that these compounds undergo a darkening on 
exposure to light. According to Baker, this is due to the forma- 
tion of an oxy-compound — in the case of the chloride, AggClo. 

Pure Silver. 

Experiment 3. — Place the silver chloride obtained in experi- 
ment 2 in a dish, wet it with dilute sulphuric acid, and lay 
a piece of sheet zinc on the mixture; metallic silver is 
precipitated and, after about one day, wholly removed from 
combination. Collect the precipitate on a filter and wash with 
water ; it is pure metallic silver, and is readily fusible into a 
single button, especially if mixed with a little borax and 
nitre. 

Note. — Any considerable quantity of silver chloride may be 
reduced to a lump of the metal by fusion in a crucible, with about 
half its weight of sodium carbonate. The chloride is also reduced 
by boiling it with caustic alkali and grape sugar until a trial 
sample is entirely dissolved by nitric acid. 



Pure Silver Nitrate. 

Experiment 4. — Dissolve the pure silver from experiment 
3 in nitric acid (3 parts by weight of silver require about 2 
or 2^ of concentrated acid diluted with 5 of water), and 
remove excess of acid by evaporating the solution to dryness 
and slightly heating the residue ; the product is pure silver 
nitrate. Dissolve it by heating with a small quantity of 
water; the solution on cooling, or on evaporation, deposits 
colorless tabular crystals of silver nitrate. 



3Ag + 4HN0, = NO + SAgNOg 
Silver Nitric acid Nitric oxide Silver nitrate 



2H,,0 

Water 



Notes. — Silver Nitrate (Argenti Nitras, U. S. P.), treated with 
4. parts of hydrochloric acid to every 100, melted at as low a 
temperature as possible, and poured into proper moulds, yields 
the white cylindrical sticks or rods connnonly termed caustic (from 
Kaio), haid, I burn), lunar caustic, or moulded silver nitrate 
(Argenti Nitras Fustis, U. S. P.). The alchemists called silver 



236 THE METALLIC RADICALS. 

Diana or Luna, from its supposed mysterious connection with 
the moon. Mitigated Silver Nitrate, Argenti Nitras M'ltigatus, 
U. S. P., is a fused mixture of one part of silver nitrate with 
two parts of potassium nitrate. 

The specimen of silver nitrate obtained in the foregoing experi- 
ment, dissolved in water, will be found useful as an analytical 
reagent. Silver nitrate dissolves in 90 percent, alcohol ; but 
decomposition occurs after a time. 

Silver salts are decomposed when in contact with organic matter, 
especially on exposure to light, or on heating, the metal itself 
being liberated, or a black insoluble compound formed. Hence 
the value of silver nitrate in the manufacture of indelible ink for 
marking linen ; hence, too, the reason of the practice of rendering 
silver solutions clear by subsidence and decantation, rather than 
by filtration through paper; and hence the cause of those cases 
of actual combustion which have been known to occur in preparing 
pills containing silver oxide and essential oil or other organic 
matter. Linen marked with silver marking-ink should not be 
cleansed by aid of bleaching liquor, as the marked parts are then 
apt to be rapidly oxidized and ''tendered," holes resulting. 
Paul says the reaction is as follows : — Ag20 + CaClgOg = 
2AgCl + CaO + O2. 

Silver Oxide. 

Experiment 5. — To a solution of silver nitrate add solution 
of potassium or sodium hydroxide, or lime-water; an olive- 
brown precipitate of silver oxide, Ag^O, is produced. The 
washed and dried oxide, Argenti Oxidum, U. S. P., is decom- 
posed by the action of heat, with production of metal. It is 
also reduced by contact with organic matter. (See preceding 
paragraph.) 

In preparing it calcium hydroxide is the precipitant usually 
employed, potassium or sodium hydroxide not being so readily 
removed by washing. Three and a half pints of good lime-water 
will decompose half an ounce of silver nitrate. 



lAgNO, 


+ Ca(OH), = 


= Ag.O 


4- 


Ca(N03), 


+ H,0 


Silver 


Calcium 


Silver 




Calcium 


Water 


nitrate 


hj'droxide 


oxide 




nitrate 





Silver oxide is also precipitated on adding ammonia water to a 
solution of silver nitrate, but it is rapidly taken up by the 
ammonium nitrate formed at the same time, argent-ammonium 
nitrate, NH.^AgNO.^. probably being formed. The direct solution 
of silver oxide in ammonia may give the highly explosive sub- 



SILVER. 



237 



stance known as Berthollet's fulminating silver (? NHgAg). 
Ordinsir J fulminating silver, C2N202Ag2, results from the interaction 
of silver nitrate, nitric acid, and alcohol. The corresponding 
mercury compound, fulminating mercury, C2N202Hg, is used in 
percussion caps. Silver Ammonium Nitrate Test-Solution is 
official. 

Methods of forming several other salts of silver are incidentally- 
mentioned in the following analytical paragraphs. 



Analytical Reactions of Silver Salts. 

To a. solution of a silver salt add hydrochloric acid or 
other soluble chloride ; a white curdy precipitate of silver 
chloride, AgCl, is produced. Add nitric acid, and boil ; the 
precipitate does uot dissolve. Pour off the acid and add 
aupahonia water ; the precipitate dissolves. Neutralize the 
aitfmoniacal solution by means of an acid ; the white curdy 
precipitate is reproduced. 



This is the most characteristic test for silver. The precipitated 
chloride is also soluble in solutions of sodium thiosulphate or 
potassium cyanide — facts of considerable importance in photo- 
graphic operations. 

Other analytical reagents besides the above are occasionally 
useful. — Hydrogen sulphide, or ammonium hydrosulphide, 
gives a black precipitate of silver sulphide, Ag^S, insoluble 
in alkalies. — Solution of potassium or sodium hydroxide gives 
a brown precipitate of silver oxide, Ag20. — Sodium phosphate 
gives a yellow precipitate of silver phosphate, Ag.^PO^, soluble 
in nitric acid and in ammonia water. — Ammonium arsenate 
gives a brown precipitate of silver arsenate, Ag3AsO^, already 
noticed in connection with arsenic acid. — Potassium bromide 
gives a yellowish-white precipitate of silver bromide, AgBr, 
insoluble in dilute acids, soluble with some difficulty in 
ammonia. — Potassium iodide produces a pale-yellow precijn- 
tate of silver iodide, Agl, insoluble in dilute acids. — It is 
changed by ammonia into a yellowish insoluble compound. — 
Potassium cyanide gives a white precipitate of silver cyanide, 
AgCN (Argenti Cyanidum, U. S. P.), soluble in excess, 
somewhat soluble in ammonia, insoluble in dilute nitric acid, 
soluble in boiling concentrated nitric acid. — Potassium chro- 
mate, K2CrO^, gives a red precipitate of silver chromate, 



238 THE METALLIC RADICALS. 

Ag^CrO^. — Potassium dichromate gives a red precipitate of 
silver auiiydrochroniate, Ag^Cr^O.. — Many organic acids give 
rise to insoluble silver salts. — Several metals displace silver 
from solution, mercury forming in this way a crystalline 
precipitate known as the silver tree, or Arhor DiaiKE. — Heated 
on charcoal with sodium carbonate in the blowpipe-flame, 
silver salts yield bright globules of silver, not accompanied 
by an incrustation as in the corresponding reaction with lead 
salts ; the experiment may be performed with the nitrate, 
which first melts, and then, like all nitrates, deflagrates, yield- 
ing a white metallic coating of silver which slowly aggregates 
to a button. 

Antidotes. — Solution of common salt, sal-ammoniac, or any other 
inert chloride should obviously be administered where large doses 
of silver nitrate have been swallowed. A quantity of sea-water or 
brine would convert the silver into insoluble chloride, and at ^e 
same time produce vomiting. 



QUESTIONS AXD EXEECISES. 

Bv what process is silver obtained" from argentiferous lead? — What 
weight of IT. S. silver coin will yield one pound of pure silver nitrate ? — 
How may the metal be recovered from impure silver salts? — Give a 
diagram showing the formation of silver nitrate. — Describe the reaction 
of lime-water with silver nitrate. — Mention the chief test for silver, and 
state how silver salts may be distinguished from those of lead and mer- 
cury. — Name the antidote for silver. 



Qualitative Analysis. 

Methods for the qualitative analysis of solutions containing any 
or all of the metals, copper, mercury (either as mercurous or as 
mercuric salt), tin (as stannous salt), lead, bismuth, cadmium, and 
silver have now to be considered. Before introducing the student 
to the systematic examination of solutions containing any or all 
of the metals of general interest, treated of in this Manual, it will 
be convenient to indicate how the particular metals just mentioned 
above, are dealt with in that systematic examination, in so far as 
dividing them into analytical groups is concerned. 

The first point to be noted is that silver and mercurous chlorides 
are insoluble, and that lead chloride is only sparingly soluble, in 
cold water. Addition of excess of hydrochloric acid, or other 
soluble chloride, to the solution, causes the complete precipitation 



QUALITATIVE ANALYSIS. 239 

of silver and mercurous chlorides (or, if no precipitate forms, shows 
the absence of those metallic radicals), and it may cause the pre- 
cipitation of some lead chloride also. After removing any pre- 
cipitate by filtration, part or the whole of the lead (if any was 
present originally), and the whole of any of the other metals men- 
tioned above, which may have been present, pass into the filtrate, 
from which they can be precipitated by means of hydrogen sul- 
phide. 

The fact that this method of dividing these metals into two 
groups for analytical purposes, is practically universally employed, 
furnishes the explanation for the separate treatment of the metal- 
lic radicals constituting the two groups, in the two pairs of pre- 
liminary analytical schemes which follow (pp. 239, 242)= The 
first pair of schemes deal with silver, mercurous, and lead salts; 
while the second pair deal with cupric, mercuric, lead, bismuth, 
and cadmium salts, and partially with stannous salts. 

The position of tin in this analytical arrangement is somewhat 
anomalous, since, in the course of the systematic separation of the 
metals, this element falls into the analytical group along with 
arsenic and antimony. The connection of this latter group (the 
arsenic group) with the group embracing copper, bismuth, etc. 
(the copper group), will be evident later, when the scheme for 
the systematic separation of the whole of the metals of general 
interest comes to be discussed (p. 244). 



DIRECTIONS FOR APPLYING SOME OF THE REACTIONS DES- 
CRIBED IN THE FOREGOING PARAGRAPHS TO THE 
ANALYSIS OF AN AQUEOUS SOLUTION OF A SALT OF ONE 
OF THE METAL.S SILVER, MERCURY (AS MERCUROUS 

salt), lead. 

Add hydrochloric acid : — 

Silver is indicated by a white curdy precipitate, insoluble 

in excess, easily soluble in ammonia water. 
Mercurous salts is indicated by a white precipitate which 

is turned black by ammonia water. 
Lead is indicated by a white precipitate, insoluble in 
ammonia water. Confirm by boiling a small portion 
of the hydrochloric-acid precipitate in water ; it dis- 
solves. 
If hydrochloric acid gives no precipitate, silver and mer- 
curous salts are absent, and lead can only be present in very 
small quantity. The presence of lead in small quantity is 
best detected, by applying- the sulphuric acid test to a fresh 



240 



THE METALLIC RADICALS. 



portion of the original solution, the tube being set aside for a 
time if the precipitate does not appear at once. ^ 

TABLE OF SHORT DIRECTIONS FOR APPLYING SOME OF THE 
REACTIONS DESCRIBED IN THE FOREGOING PARAGRAPHS 
TO THE ANALYSIS OF AN AQUEOUS SOLUTION OF ANY OR 
ALL OF THE METALS SILVER, MERCURY (AS MERCUROUS 
salt), LEAD. 

Add hydrochloride acid in excess, filter, and wash the pre- 
cipitate with a small quantity of cold water. 



Precipitate 
Pb Hg (ous) Ag 
Wash on the filter with boiling water. 



Residue 
Hg (ous) Ag 
Add NAPH. 



Eesidue 

Hg 
(mercurous), black 



Filtrate 

Ag 

Add HNO3 white ppt. 



Filtrate 
Pb 

Add 

H2SO, 

white ppt.^ 



Fihrate 
Pb 

Add 

H2SO, 

white ppt^ 



DIRECTIONS FOR APPLYING SOME OF THE REACTIONS DE- 
SCRIBED IN THE FOREGOING PARAGRAPHS TO THE 
ANALYSIS OF AN AQUEOUS SOLUTION OF A SALT OF ONE 
OF THE METALS COPPER, MERCURY ( AS MERCURIC SALT), 
TIN (as stannous SALT), LEAD, BISMUTH, CADMIUM. 



Note that solutions of cupric salts have a blue color. 
Acidulate the liquid with hydrochloric acid and pass 

' Liquids containing only a small quantity of lead do not readily 
yield lead sulphate on the addition of sulphuric acid. Before lead can be 
said to be absent, therefore, the liquid should be evaporated to dryness 
with one drop of sulphuric acid, and the residue digested in water; any 
lead sulphate then remains as a heavy, white, insoluble powdex*. 



QUALITATIVE ANALYSIS. 



241 



hydrogen sulphide through it until the mixture, after shaking, 
smells of the gas: — 

Cadmium salts give a yellow precipitate, insoluble in 
ammonia water easily soluble in hot dilute hydro- 
chloric acid. 

Cupric, mercuric, stannous, lead, and bismuth salts give 
dark- brown or black precipitates. In the case of a 
mercuric salt, the precipitate may be white or pale-yel- 
low at first, but it rapidly becomes orange, brown, and, 
finally, black. In the case of a lead salt, the precipi- 
tate is sometimes reddish-brown if much hydrochloric 
acid is present, but it becomes black on dilution of the 
solution and addition of enough hydrogen sulphide. 

To distinguish cupric, mercuric, stannous, lead, and bis- 
muth salts from one another, add potassium iodide to another 
portion of the original solution: — 

A pale-brownish mixture (which really consists of a 
nearly colorless precipitate of cuprous iodide in a 
yellow or brown solution of iodine) indicates a cupric 
salt. The brown color disappears and the precipitate 
is seen to be nearly colorless, when solution of sul- 
phurous acid is added. Compare reaction 7, p. 208. 

A yellowish-red precipitate, rapidly becoming bright-red, 
soluble in excess of potassium iodide, indicates a mer- 
curic salt. 

The production of a pale-yellow precipitate, or, in dilute 
solutions, of none at all, indicates a stannous salt, 

A yellow precipitate, insoluble in excess of potassium 
iodide, soluble in boiling water, indicates a lead salt. 

A bright-yellow solution, or a brown precipitate which 
dissolves in excess of potassium iodide to form a bright- 
yellow solution, indicates a bismuth salt. 

TABLE OF SHORT DIRECTIONS FOR APPLYING SOME OF THE 
REACTIONS DESCRIBED IN THE FOREGOING PARAGRAPHS TO 
THE ANALYSIS OF AN AQUEOUS SOLUTION OF SALTS OF TWO 
OR MORE OF THE METALS, COPPER, MERCURY (AS MERCURIC 
salt), lead, BISMUTH, CADMIUM. 



Acidulate the liquid with hydrochloric acid and pass hydro- 
gen sulphide through it until the mixture, after shaking 
smells of the gas ; filter. 
16 



242 



THE METALLIC RADICALS, 



Precipitate 

Cu Hg (ic) Bb Bi Cd 

Wash with water ; boil with HNO3 ; dilute with 

water and filter. 



Residue 

Hg(ic) 

Black 

Confirm by 

Cu test 
in original 

solution 



Filtrate 

Cu Pb Bi Cdi 

Add Is H4OH in excess, filter. 



Precipitate 
Pb Bi 

Wash, dissolve on 

filter in a few drops 

of dilute HNO3 

dilute, filter. 



Ppt. 
Bi 

white 



Filtrate 

Pb 

Add 

H2SO, 

set aside ; 

white ppt. 



Filtrate 

Cu Cd 

(Blue if Cu present), 

Add KCN in 

excess, and pass 

H.,S. 



Ppt. 
Cd 

yellow 



Filtrate 

Cu_ 

Acidify 

with 

acetic acid 

brown 

ppt. 



Filtrate 

Dilute with 

H2S solution 

so, as to 

ensure 

complete 

precipitation 

of 
Pb, Bi, Cd, 

the 
sulphides of 
which are to 
some extent 
soluble in 
cold dilute 
HCl. 
If any 
further pre- 
cipitate is 
produced, 
it may be 
added to 
the original 
precipitate, 
or examined 
separately. 



The Analytical Classification of Metals. 
Systematic Analysis. 

The following Tables, giving directions for the analytical 
examination of the solutions for the presence of practically any of 
the metallic radicals hitherto considered, include and, to a certain 
extent, epitomize the Tables previously given under the different 
groups. The order of addition of the group-reagents is arranged 
according to a carefully devised plan which is set forth in the 
following outline of the annexed analytical Tables : — 



1 The possible presence of tin, whether as stannous or stannic salt, is 
not considered in the separation described here, since, in the systematic 
examination of a solution w'hich might contain tin, along wdth copper, 
mercury, etc., any stannous or stannic sulphide is removed from the cup- 
ric, mercuric, etc., sulphides before the examination of the latter sulphides 
if proceeded with. {See p. 244). 



QUALITATIVE ANALYSIS. 



243 



OUTLINE OF THE 


ANNEXED 


ANALYTICAL TABLES. 




HCl 


H,S 


NH.HS 


(NH,),C03 


ffi: 




. Hg 


Cd ~ 




Zn ~ 


a 

2 


Ba 


Mg 


K 


(as mercu- 








s 








rous salt) 


Cu 


W 


Mn^ 














•* 




■Iw 


Sr 




Na 


Pb 


Hg 




Co 


■Sl^i 








(partially) 


(as mercuric 
salt) 


■a 


Ni J 




Ca 




NH^ 


Ag 


Ph 

(entirely) 


3 

3 

















Al 1 


^ 










Bi 






g 
















•^w 










As 1 

(as arsenous 




Fe 






Li 






or arsenic 






g;^! 










salt) 






t-9 










Sb 


4 


Cr , 


W 










Sn 


W* 
.^ 












(as stan- 


a 












nous or 


<v 












stannic 


2 












salt) 


3 
1 












Au 














Pt 













Note. — The student should practice the examination of aqueous solutions 
of salts of the above metals, by aid of the Tables, until he is able to ascer- 
tain with facility and accuracy which metalic radicals are present. In 
this way he will best perceive the peculiarities of each element, and the 
general relations of the elements to each other. 

The foregoing outline indicates that hydrochloric acid, which is 
the first group-reagent added, precipitates silver and mercurous 
chlorides and partially precipitates lead chloride (unless the lead 
solution is very dilute). The filtrate obtained on removing the 
hydrochloric acid precipitate is next treated with hydrogen sul- 
phide, which precipitates the metals of the copper and arsenic 
groups together as sulphides. The sulphides of these two groups 
behave differently when digested with yellow ammonium hydro- 
sulphide (or, what comes to the same thing, ammonium hydrosul- 
' See Experiment 5, p. 141. 



244 THE METALLIC RADICALS, 

phide and a pinch of sulphur), those of the arsenic group dis- 
solving in this reagent, Avhile those of the copper groiip remain 
undissolved. [See note on p. 242). Hence, when the sulphides 
of the two groups have been precipitated together and filtered off, 
the mixed precipitate is treated with yellow ammonium hydro- 
suli^hide so as to effect the separation of arsenic group sulphides 
from the copper group sulphides, while the filtrate still contains 
the metals of the iron, zinc, and barium groups along with mag- 
nesium and the alkali metals. 

A very common mode of dealing with the filtrate (and the one 
adopted in the annexed Tables) is to add excess of ammonia and 
then ammonium hydrosulphide to it. The ammonia first neutral- 
izes the hvdrochloric acid present in the filtrate, forming with it 
ammonium chloride :— HCl ^XH^H = XH.Cl + H^O ; and as 
soon as this action has been completed, it forms some ammonium 
hydrosulphide with the excess of hydrogen sulphide present. This, 
together with more ammonium hydrosulphide which is added, 
precipitates, as sulphides or hydroxides, all the metals of the 
iron and zinc groups. The ammonium chloride, formed by the 
first interaction of the ammonia with the hydrochloric acid, pre- 
vents the precipitation of magnesium at this stage. The metals 
of the barium group, along with magnesium and the alkali metals, 
pass into the filtrate. The barium groujD metals are subsequently 
precipitated as carbonates by the addition of ammonium carbon- 
ate ; and magnesium and, to some extent, lithium as phosphates 
by means of ammonium phosphates, as already described on p. 
128, where the mode of dealing with the other alkali-metals is 
also discussed. 

Of the accompanying Tables, the first includes directions for the 
analysis of an aqueous or only slightly acid solution containing one 
salt, of any of the metals hitherto considered. Here the color of 
the precipitate or precipitates afforded by a metal given under 
circumstances must largely be relied on in attempting the detection 
of the various elements. 

The folded Table is intended as a scheme for the analysis of 
solutions containing salts of more than one metal. It is a compil- 
ation from the foregoing reactions and may often be altered or 
A'aried in arrangement to suit the requirements of the analyst. 

The analysis of solutions containing only one metal will serve to 
impress the memory Avith the characteristic tests for the various 
metals and other radicals, and familiarize the mind with chemical 
principJes. More thorough anahi:ical and general chemical 
knowledge is only acquired on working on such mixtures of bodies 
as are met with in actual practice, beginning with solutions which 
may contain any or all of the members of a group [see previous 
pages), then examining solutions containing more than one group, 
and finally analyzing liquids in which are dissolved several salts 
of any of the common or rarer metals. 



TABLE OF SHORT DIRECTIONS FOR APPLYING SOME C 

SAL 
Add hydrochloric acid. 



Precipitate 






1 


Hgrous) Pb Ag 




Wash, boil with water, filter. 


i 


Precipitate 


Filtrate 


Pi 

Cd Cu Hg(ic) 


HgCous^ Ag 


Pb 


Wash, add NH^OH. 


Add H2SO4. 


Collect, wash, d 




White ppt. 


Ppt. 


FDtrate 


Precipitate 


Hg 


Ag 




Cd Cu Hg{ic) Pb j!i 


(ous). 


Add HNOo. 




Wash, boil in HNO3, ^''t r. 


Black. 


White ppt. 




1 


See also p. 247. 


Kesiiiue 


Filtrat 




Hg 


Cd Cu PI i 




(ic). 


AddNH^OH i.ei. ! 




Black. 


1 




Confirm !l| 




by Cu 
test in 


•1 




i 




original 
solu- 


Precipitate 
Pb Bi 


nitrate ii' 
Cd Cu 1 




tion. 


Wash, add a few 


Add KCy and f 






drops HNO3, 


H2S. 






dilute, filter. 


Pp.. .ill. 1 


Ppt. 


Filt. 






Bi 


Pb 


Cd 


Cu 






White 


Dilute, 


Yel- ; 


Acidify 






See 


add 


low. 1 with' 






pp. 


H2SO4, 
set aside. 


; HC2H3O2. 






248, 


Brown 






249. 


White 
ppt. 


ppt. • 

! 




See also foot note, 


' 



QUALITATIVE ANALYSIS. 



245 



^^^ol^^^^-^? 



o 



_'^ M i-rt "^ 'TIS 



So 



^ P M a'^P III 

£- <ti p o <j p^ 






o 

aw 



CD S^'TIS 

^g 2. 

oo O 






."^ V ' o o^ '=^ o' 

black ^ ^^ a*^ 

^p ^ a^ ^S^ 



P o- 



hrjp 



_. Cr H-l r" 



§ ^ black, yellow. 



H^ i^ 2 

3 P ^ H^ 

, ,2". oc 

^§ 5"^ 

OQ ? ^ Q 
CD O ^' 



■" ^ '" 0^ ' """^ ^^ CD 

a: ^g ^ CD o 





Precipitate 
Ba Sr Ca 
Collect, wash, dis- 
solve in HC2H3O2, 
add K^CrO,. 


1— 1 

p "cc 































<r»- 


itate, t 
inal sc 
flame 


(—1 




CD 
00 


CD ii::; 
r^ 


B 
3 


^ 
^ 
P 


precip- 
est orig- 
lution in 
on loop 



!> CD « 
pi. CD 

o 



^<1 

>« CD 



In 

p 

<! 

CD 

O 



9 

CfC3 
P 
<1 



O 



p- 
p- 





H 


^^ 


> 





tr' 


•^ 


t?d 








•^ 


»=^ 





CO 


^ 


H 


t> 




w 


w 


Hi 


trt 


CO 
> 




M 




H 





GO 


:^ 




r/i 







►^ 


w 










'Pi 






W 


H 




K 





t?d 


t'j 






> 


i4 


X 


R 


;> 


H 


t-i 





k! 

w 







g 


Ul 


^ 








•^ 


!^ 






f> 


;> 


S! 


t^ 




G 


;> 







t5d 


c! 


>- 


W 


W 





w 


n 


?3 


in 


f^ 





M 


PS 







rr 


t^ 




Kl 


W 






(/J 


H 


t-" 






Hi 










> 


•i< 





iT: 


e 


C 




K 


nr 










Jx| 


r 


c 


c* 



SHORT DIRECTIONS FOR APPLYING SOME OF THE FOREGOING ANALYTICAL" REACTIONS TO THE ANALYSIS OP AN AQUEOUS OR ONLY SLIGHTLY ACID SOLUTION OF Omlu^ 

SAUrS Of ANY OP THE COMMON OR RARER METALS OF GENERAL INTEREST. 
Add hydrochloric acid. 



TABLE OP 



Precipitate 

Hg.ous) Pb Ag 

Wash, boil with water, filter. 



Precipitate 

Hs.ous* Ag 

Wasfi, add NH^OH. 



Filtrate 

Pb 

Add H.,S04. 

White ppt. 



Ppt. i Filtrate i 

Hg ; Ag 

(ous). Add HNO3. 
Black. I White ppt. 



See also p. 24" 



C.i Cu Hg(ic) Pb Bi As(ous)(ic) Sb Sn(oiis)(lc) Zn Mn Jco^ Ni Al Fe(ous)(ic) Cr Ba Ca Sr Mg Li K Na NH, 
^^ ' Pass H2S through the liquid, filter. 



P ecipitate 
Cd Cu Hg(ic) Pb Bi As Sb Sn 
Collect, wash, digest in KH^SH, filter. 



Precipitate 
Cd Cu Hg(ic) Pb 
Wash, boil in HNO3, t 



Filtrate 

As Sb Sn 

Add'dilute HCl, lilter, drain well, add strong 

HCl, boil, dilute slightly, filter. 



Kesidu 
Hg 
(ic). 
Black 
Confirm 
by Cu 
test in 
original 
solu- 
tion 



Filtrat- 
ed Cu Ph 
Add NH.OH, 



Precipitate 

Pb Bi 

iWash, add a few 

' drops HNO3, 

dilute, filter. 



As 

, Yellow. 

•Confirm 

by Fleit- 

mann's 

test. 



Ppt. 


Filt. 


Pp.., 


Bi 


Pb 


Cd i 


White 


Dilute, 


Yel- 


See 


add 


low. 


^Si 


H2SO4, 
set aside. 




249. 


White 
ppt. 


1 



Filtrate 
Cd Cu 
Add KCt and 1 



Cu 

Acidify 

with 

HCsH^O.^ 

Brown 

ppt. 



Filtrate 

Sn Sb 

Pour into H-apparatus. 



remains on Zn. 
Dissolve in HCl 
and :«.!iijlv tt-sts. 



■ugiit whe-n necessary 



See also foot note, 



Filtrate 

Zn Mn Co Ni Al Fe Cr Ba Ca Sr Mg Li K Na NH. 

Add NHiCl.NHiOH, NH^SH, warm gently and filter. 



Precipitate 

Zn Mn Co Ni Al Fe Cr 

Collect, wash, dissolve in HCl with a few drops of HNO3 

boil, add NH4OH, stir, filter. 



Precipitate * 

Fe Al Cr 

Wash, dry, fuse on foil with 

Na^COg and KNO..,, boil in 

water and filter. 



Fe.^Oa, 
brown. 
Test 
original 
solution 

for 
ferrous 

state. 



•Filtrate. 
If yellow, Cr pre- 
sent. Divide in 
two parts. 



Sol. 
Al 
Add 
NH4CI 
and 
warm. 
M'hite 
ppt. 



Cr 
Add 

and exce.ss 
of AgNO;,; 
red ppt.' 
Or boil 
with H ,S04 
and spirit. 

solution. 



See also p. 249. 



>" Test this also for Mn, by 
Cruui's process, p. 14). 



Filtrate 

Zn Mn Co Ni 

Acidify with H<'.,H30.„ pass HoS, 

filter. 



Sol. 

Mn 

Add 
NH^OH 

and 
NH^SH. 

Pink, 
turning 
brown. 



Searcli 
also fur 
Mniii 

the 
FeAK': 

ppt. 



Precijiitate 

Zn Co Ni 
Boil with HCl and a little 
HNO.ji add KOH, filter. 



.\dd 

White 
ppt. 



Precipitate 

Co Ni 

Dissolve in HCl, 

and proceed as 

directed on page 

14.5. 



I Ca Sr Mg Li K Na NH 
Add (NHJ,C03, warm, filter^ 



Precipitate 

Ba Sr Ca 

Collect, wash, dissolve in 

HC..H3O,, add excess of 

KaC'rO., filter. 



Filtrate 
Jfg Li K Na NH. 
dCNH,),HAsO„ stir, filter 



Ppt. 

Ba 

Yellow. 



Filtrate 1 Ppt. 

Sr Ca ; Jig 

Add dilute H.,S04, White 

let stand, filter, i 



While 



Filt. 

Ca 

Add 

NH4OH and 

f'hite ppt. 



See also p. 2o0, and t 
more delicate separati 
given on p. 12S. 



Filtrate 
Li K Na NH, 
Evaporate to small 
bulk. Add NH.OH. 



Ppt. I Filtrate 

Li K Na NH, 

See Evaporate, 

3. 2.50. ignite, dissolv 

I KbyPtCi,, 

Na by flame. 

iNHj in origioal 

' solution. 



QUALITATIVE ANALYSIS. 



245 



_^ P-i i* CD ha- '^ td 






J^. p ^ S "^ 



o 

aw 

cTcfS, 



o^ a. r- J J^ ffi :^ ^ 

I- . ^. L_, p- H^ ^ 















P- 



^^^ b 



^ 5* <^ 
^ p 2. 
•^ »— ' p' 

<i 1=-- <i> 
o'S. S- 

^ 2 5?^ 
S 2 g- 



^ , ' o ^ '^ ^ 

black ^ ^^ K*^ 



I'd t> 02 Oi CK t> ^ 

CO 



p 

w 



black, yellow. 



^ S 2 
■ 2- 






p: i=- ! 






? ^ g 
a2§.£ 


















2.? 

>^.?H^, P fD 



^:p 



o tb 
i-tj p 



W ^ t~' B ^ 



2-0 2-^ 






■ o oo 



CD 

2 ^i 



H- 2 O CD 

o P 3,2. 
h2 S'o?*^' 



ffilo 

h> CD " 

o?? P 
^ p- <1 

• P^ CD 



P C/2 



W' 



o. 



W 



W 

CfC5 
P 
<1 
CD 



P- 

p. 



o t-" 

o o 

td W 

2 ^ 

^ ^ 



O t?3 

s ^ 

O M 

£§ 

Jd O 
fe^ c! 

p3 02 



246 THE METALLIC RADICALS. 

The author cannot too strongly recommend students thoroughly 
to master the art of analysis, not only on account of its direct 
value, but because its practice enables them rapidly and soundly 
to acquire a good knowledge of Chemistry, and greatly improve 
their general mental faculties. 

General and Special Memoranda relating to the 
PRECEDING Analytical Tables. 

General Memoranda. 

These Tables are constructed for the analysis of salts more or 
less soluble in water. — The student has still to learn how sub- 
stances insoluble in water are to be brought into a state of solu- 
tion; but once dissolved, their analysis is effected by the same 
scheme as that just given. The Tables, especially the longer 
folded one, may therefore be regarded as fairly representing the 
method by which metallic constituents of chemical substances are 
separated from each other and recognized. 

The group-reagents adopted in the Tables are hydrochloric acid, 
hydrogen sidphide, ammonium hydrosidphide, ammonium carbonate 
and ammonium phosphate. If a group-reagent produces no precipi- 
tate, it is evident that there can be no member of the group 
present. At first, therefore, add only a small quantity of a group- 
reagent, and if it produces no effect add no more; for it is not 
advisable to overload a solution with useless reagents ; substances 
expected to come down as precipitates are not infrequently held 
in solution in the liquid by excess of acid, alkali, or concentrated 
aqueous solution of some group-reagent, thoughtlessly added. 
Indeed, experienced manipulators make preliminary trials with 
group-reagents on a few drops only of the liquid under exami- 
nation ; if a precipitate is produced, it is added to the bulk of the 
original liquid, and the addition of the group-reagent is continued; 
if a precipitate is not produced, the few drops are thrown away; 
and the unnecessary addition of a group-reagent thus avoided alto- 
gether, an advantage fully making up for the extra trouble of 
making a preliminary trial. — While shunning excess, however, 
care must be taken to avoid deficiency; a substance only partially 
removed from solution through the addition of an insufficient 
amount of a reagent will appear where not expected, be constantly 
mistaken for something else, and cause much trouble. It is a good 
plan, when a group-reagent has produced a precipitate and the 
latter has been filtered off, to add a little more of the reagent to 
the clear filtrate ; if more precipitate is produced, an insufiicient 
amount of the group-reagent was introduced in the first instance ; 
but the error is corrected by simply refiltering ; if no precipitate 
occurs, the mind is satisfied and the way cleared for further opera- 
tions. 



QUALITATIVE ANALYSIS. 



247 



Group-precipitates, or any precipitates still requiring examin- 
ation, should, as a rule, be well washed before further testing; 
this is to remove the aqueous solution of other substances adhering 
to the precipitate, so that subsequent reactions may take place 
between the reagents used and the precipitate only. — A precipi- 
tate is sometimes in so fine a state of division as to retard filtration 
by clogging the pores of the paper, or even to pass through the 
filter altogether ; in these cases the mixture may be warmed or 
boiled (or a fresh quantity of the original solution may be warmed 
before the group-reagent is added), which usually causes aggrega- 
tion of the particles of a precipitate, and hence facilitates the pas- 
sage of liquids. 

Division of work. — It is immaterial whether a solution be first 
divided into group-precipitates or each precipitate be examined 
as soon as produced; if the former method be adopted, confusion 
will be avoided by labelling or marking the funnels or papers 
holding the precipitate ''the HCl ppt.," "the H^S ppt.," and so 
on. 

The colors and general appearance of the various sulphides and 
hydroxides precipitated should be borne in mind, as the absence 
of other substances, as well as the presence of those precipitated, 
is often at once thus indicated. 

Application of confirmatory tests must be frequent. 

Results of analyses should be recorded neatly in a memorandum 
book; a, for correction and endorsement by the teacher; b, for 
fiiture reference by the student or by those who may need evidence 
respecting his labors; and, c, to promote mental orderliness. 

The various reactions which occurs in an analysis have already 
come before the reader in going through the tests for the individ- 
ual metals or in other analytical operations; it is unnecessary, 
therefore, again to construct equations or diagrams. But the 
reactions should be thought over, and if not perfectly clear to the 
mind, be written out again and again, till thoroughly understood. 



Special Memoranda. 

The Hydrochloric-acid precipitate may at first include some anti- 
mony and bismuth as oxychlorides, readily dissolved, however, 
by excess of acid. — If either of these elements be present, the 
washings of the precipitate will probably be milky; in that case 
add a few drops of hydrochloric acid, which will clear the liquid 
and make way for the application of the test for lead. — The 
silver chloride and mercurous chloride precipitate should not be 
long in contact with the ammonia, or silver will be reprecipitated 
thus: — 

2AgCl + 2HgCl + 4NH3 = NHg^Cl, NH.Cl + 2NH,C1 + 2Ag 



248 THE METALLIC RADICALS. 

The hydrogen sulphide precipitate may be whitish, in which case 
it is nothing but sulphur ; for, as ah'eady indicated, ferric salts 
are reduced by hydrogen sulj)hide to ferrous, and chromates to 
chromic salts, finely divided whitish sulphur being deposited: — 

4FeCl3 H- 2H2S = 4FeCl2 + 4HC1 + S^ ; 
4Cr03 + 2H2S + 12HC1 = ^CyC\ + I2H2O + 38^ 

But the precipitate may also be very slightly yellow, or even 
white when only a mercuric salt is present, through an insuffi- 
ciency of hydrogen sulphide having produced a chlorosulphide. 
The gas should be passed through the liquid until, even after well 
shaking, the latter smells strongly of hydrogen sulphide. 

The portion of the hydrogen sulphide precipitate dissolved by 
ammonium hydrosulphide may include a trace of copper, cupric 
sulphide being not altogether insoluble in ammonium hydrosul- 
phide. — On adding hydrochloric acid to the ammonium hydro- 
sulphide solution, whitish or yellowish sulphur only may be pre- 
cipitated, yellow ammonium hydrosulphide always containing free 
sulphur. — Concentrated hydrochloric acid does not readily dis- 
solve small quantities of antimonious sulphide out of much 
arsenous sulphide ; and, on the other hand, the concentrated 
hydrochloric acid takes into solution a small quantity of arsenous 
sulphide if much antimonious sulphide be present. The precipi- 
tates or the orginal solutions should therefore be examined by the 
other (hydrogen) tests for these elements if doubt exists concern- 
ing the presence or absence of either. Tin remains in the hydro- 
gen-bottle in the metallic state, deposited as a black powder on 
the zinc used in the experiment. The contents of the bottle are 
turned out into a dish, ebullition continued until evolution of 
hydrogen ceases, and the zinc is taken up by the excess of sul- 
phuric acid employed ; any tin is then filtered out, washed, dis- 
solved in a few drops of hydrochloric acid, and the liquid tested 
for tin by the usual reagents. — Tin may be detected in the 
mixed tin, arsenic, and antimony sulphides by the blowpipe 
reaction (p. 195). 

TJie portion of the hydrogen sulphide precipitate not dissolved by 
ammonium hydrosidphide may leave a yellow semi-ftised globule 
of sulphur on boiling with nitric acid. This globule may be black, 
not only from presence of mercuric sulphide, but also from 
enclosed particles of other sulphides protected by the sulphur from 
the action of the acid. It may also contain lead sulphate, pro- 
duced by the action of nitric acid on lead sulphide. In cases of 
doubt the mass must be removed from the liquid, boiled with nitric 
acid till dissolved, the solution evaporated to remove excess of 
acid, and the residue examined ; but usually it may be disre- 
garded. — Before testing for bismuth, any considerable excess of 



QUALITATIVE ANALYSIS. 



249 



acid should be removed by evaporation, and the residual liquid 
should be freely diluted. If no precipitate (bismuth oxynitrate) 
appear, ammonium chloride solution may be added, bismuth oxy- 
chloride more readily forming than even oxynitrate. Or, any 
nitric acid or sulphuric acid having been neutralized by adding 
ammonia, hydrochloric acid is added and then potassium iodide ; 
a rich orange color results if bismuth be present. — Bismuth may 
also be detected in the mixed precipitated bismuth and lead hydrox- 
ides, obtained in the ordinary course of analysis, by dissolving a 
portion of the precipitate in acetic acid, adding the liquid to the 
hot solution of lead iodide mentioned in the reactions for bismuth 
(p= 231). — In testing for lead by means of sulphuric acid, the 
liquid should be diluted and set aside for some time. 

Mercury may also be isolated by digesting the hydrogen sul- 
phide precipitate in sodium hydrosulphide, instead of ammonium 
hydrosulphide. The arsenic, antimony, tin, and mercury sul- 
phides are thus dissolved out. The mixture is then filtered, excess 
of hydrochloric acid added to the filtrate, and the precipitated 
sulphides collected on a filter, washed, and digested in ammonium 
hydrosulphide ; mercury sulphide remains insoluble, while the 
arsenic, antimony, and tin sulphides arje dissolved. By this 
method copper also appears in its right place only, cupric sul- 
phide being insoluble in sodium hydrosulphide. The other metals 
are then separated in the usual way. 

The ammonium hydrosulphide precipitate may, if the original 
solution was acid, contain barium-group and magnesium phos- 
phates, oxalates, silicates, and borates. These will subsequently 
come out with the iron, and, being white, give the iron precipi- 
tate a light-colored appearance ; their examination must be con- 
ducted separately, by a method described subsequently in connec- 
tion with the treatment of substances insoluble in water. — The 
precipitate containing aluminium, iron, and chromium hydroxides 
often contains some manganese. This manganese may be detected 
by washing the hydroxides to remove all trace of chlorides, boil- 
ing Avith nitric acid, adding either lead peroxide or red lead, and 
setting the vessel aside; if manganese be present, a red or purple 
liquid is produced. — Nickel sulphide is not easily removed by 
filtration {see p. 143) until most of the excess of ammonium hydro- 
sulphide has been dissipated by prolonged ebullition. 

The ammonium carbonate precipitate may not contain the whole 
of the barium, strontium and calcium in the mixture, unless free 
ammonia be present ; for the carbonates of these metals are solu- 
ble in water charged with carbonic acid. If, therefore, the liquid 
is not distinctly ammoniacal, ammonia water should be added. 
— Neither ammonium carbonate nor ammonia wholly precipitates 
magnesium salts ; and as partial precipitation is undesirable, 
ammonium chloride, if not already present in the liquid, should 
be added. — In the Table opposite p. 245, it is directed that stron- 



250 THE METALLIC RADICALS. 

tium be separated from calcium by adding dilute sulphuric acid 
to the acetic acid solution. This reagent, unless extremely dilute, 
may precipitate calcium. Any such loss of calcium is in itself of 
little consequence, because enough calcium sulphate remains in 
the filtrate to afford a calcium reaction when ammonia water 
and ammonium oxalate are subsequently added. But the calcium 
sulphate precipitated by the sulphuric acid may be wrongly set 
down as strontium sulphate. Therefore test a little of the acetic 
acid solution for strontium by adding an aqueous solution of cal- 
cium sulphate, when, if no precipitate falls after setting aside for 
several minutes, strontium may be regarded as absent. If a pre- 
cipitate occurs, strontium is present : the rest of the acetic acid 
solution is then tested for calcium as directed in the Table, the 
final testing by means of ammonium oxalate being, of course, pre- 
ceded by the addition of ammonia water. Barium may be over- 
looked if oxidation happens to have converted any sulphur into 
sulphuric acid. 

Lithium. — Should a precipitate, supposed to be due to lithium, 
be obtained, it must be tested in the Bunsen flame. If the 
characteristic crimson flame coloration is not observable, the pre- 
cipitate is probably due to a small quantity of magnesium, which 
not infrequently shows itself under the conditions requisite for 
the precipitation of lithium. If present only in minute propor- 
tions, the lithium may also remain with the alkali-metals; it can 
then be detected by means of the spectroscope. Such a method 
of examination is called spectrum analysis, a subject of much 
interest and of no great difliculty ; it will be described briefly in 
connection with the methods of analyzing solid substances. 



QUESTIONS AND EXERCISES. 



Describe a general method of analysis by which the metal of a single 
salt in a solution could be quickly detected.— Give illustrations of black, 
white, buff, yellow and orange sulphides. — Mention the group-reagents 
usually employed in analysis. — Under what circumstances may a hydro- 
chloric acid precipitate contair. antimony or bismuth ? — If a hydrogen 
sulphide precipitate is white, what substances are indicated? — Give 
processes for the qualitative analysis of liquids containing the following 
substances: — a. Arsenic and Cadmium, h. Bismuth and Antimony, 
c. x-Vntimony and Mercurous salt. d. Silver and Mercurous salts, e. Fer- 
rous and Ferric salt. /. Aluminium, Iron, and Chromium, g. Arsenic, 
Antimony, and Tin. h. Lead and Strontium. /. Lead and Mercuric salt, 
j. Copper and Arsenic, h. Aluminium and Zinc. I. Iron and Copper. 
m. Iron, Sodium, and Arsenic. ?(. Mercury, Manganese, and Magnesium. 
0. Zinc, Manganese, Nickel, and Cobalt, p. Barium, Strontium, aud 
Calcium, q. Zinc, Magnesium, and Ammonium, r. Aluminium and 
Magnesium, s. Iron, Barium, and Potassium, t. Magnesium, Calcium, 
and Potassium, u. Silver, Antimony, Zinc, Barium, and Ammonium. 



THE ACID RADICALS. 251 



THE ACID EADICALS. 



With the exception of ammonium, NH^, the twenty-seven radi- 
cals which have up to this point mainly occupied attention, are 
metals. They have been studied for the most part, not in the 
free or uncombined state, but in the condition in which they exist 
in salts, i. e., as the metallic radicals of salts. As already men- 
tioned {see p. 65), salts may be regarded as composed of a metallic 
radical united with an acid radical. Every acid, too, may be 
regarded as consisting of hydrogen, which plays the part of a 
metallic radical, united with an acid radical; and hence the acids 
are sometimes called hydrogen salts. When the place of this 
hydrogen in an acid is taken by a metal, the product is simply 
called a salt. In this section of the Manual, we shall take up the 
study of a number of important salts from the point of view of 
the acid radicals which they contain and, incidentally, we shall 
also study the acids, in which these radicals occur in combination 
with hydrogen. 

Just as there are univalent, bivalent, etc., metallic radicals, so 
there are univalent, bivalent, etc., acid radicals. The acids cor- 
responding to these radicals contain one, two, etc., atoms of 
displaceable hydrogen, and on this account are called monobasic, 
dibasic, etc., acids : thus, hydrochloric acid, HCl, is monobasic ; 
sulphuric acid, H^SO^, is dibasic; orthophosphoric acid, H^PO^, 
is tribasic. Acids of higher basicity are also known. 

The student should note carefully the signification of the words 
strong and weak as applied to acids, and must not confuse the 
ideas implied by these terms with those conveyed respectively by 
the description of acids as concentrated and dilute (not necessarily 
"diluted," i. e., prepared by dilution). A strong acid is one 
which exhibits the characters of an acid in a well-marked manner, 
while a weak acid only possesses these characters to a limited 
extent. Considered in this respect, sulphuric acid is a strong- 
acid, while acetic acid is a weak one. The state of concentration 
of an acid is often described as its "strength," but this usage is 
not to be commended, the single word "concentration " being the 
term which is now usually employed in chemistry to designate 
this degree of concentration or "state of concentration." Sul- 
phuric acid, even when dilute, is still a strong acid, while acetic 
acid, even when highly concentrated, is still a comparatively 
weak acid. With regard to two samples of dilute acid, the one 
of which contains, say, fifteen, and the other twenty percent, of 
sulphuric acid, it would be correct to say that the concentration of 
the latter is greater than that of the former; /. <•., that in any 



252 



THE ACID RADICALS. 



given volume of the latter solution there is more sulphuric acid 
than in the same volume of the former solution. 



HYDROCHLORIC ACID, HCl, AND OTHER CHLORIDES. 

The acid radical of hydrochloric acid and of other chlorides is 
chlorine, CI. Chlorine occurs in nature chiefly as sodium chloride, 
NaCl. Sodium chloride is a very abundant substance, occurring 
either solid as rock-salt, deposits of which exist in Cheshire, at 
Stassfurt, and elsewhere, or in solution in the water of all seas. 
Common table-salt is more or less pure sodium chloride in minute 
crystals. Chlorine, in hydrochloric acid and the chlorides, is 
univalent (CF) ; its atomic weight is 35.18. The molecular 
formula for chlorine is CL. Hvdrochloric acid is a monobasic acid. 



HYDROCHLORIC ACID. 

Experiment 1. — To a few fragments of sodium chloride in 
a test-tube or small flask, add about an ^qual weight of sul- 
phuric acid ; colorless hydrochloric acid gas is evolved, and 

Fig. 37. 




Preparation of hydrochloric acid. 



sodium hydrogen sulphate remains. Adapt to the mouth of 
the vessel, by means of a perforated cork, a piece of glass 
tubing bent to a right angle; heat the mixture (Fig. 10, p. 34, 
or Fig. 37, above) and convey the gas into a little water; 
solution of hydrochloric acid results. 



NaCl 

Sodium 
chloride 



H..SO. 



HCl 



Sulphuric Hydrochloric 
acid acid 



NaHSO, 

Sodium hydrogen 
sulphate 



CHLORIDES. 2o^> 

The product of this operation is the nearly colorless IoHcI \ e.) 
sour liquid commonly termed hydrochloric acid. When of certain 
"concentrations" (determined by volumetric analysis), it forms 
Acidum Hydrochloricum, U. S. P., Acidum HydrochloriGum 
Dilutum, U. S. P. The former has a specific gravity of 1.158, 
and contains 31.9 percent, of real acid; the latter, specific 
gravity 1.049, Avith 10 percent, of real acid, is made by diluting 
100 parts by weight of the more concentrated acid with 219 parts 
of water. The above process is that of the manufacturer — larger 
vessels being employed, and the gas being freed from any trace 
of sulphuric acid by washing. Other chlorides yield hydro- 
chloric acid when heated with sulphuric acid; but sodium chloride 
is always used because it is plentiful and therefore cheap. 

Commercial hydrochloric acid is a by-product in the manufacture 
of sodium carbonate from common salt (by the process in which 
sodium chloride is first converted into sulphate, hydrochloric acid 
being liberated and dissolved in water). The impure acid has a 
yellow color and is liable to contain iron, arsenic, alkali-metal 
salts, sulphuric acid and nitrous compounds ; sometimes, also, 
sulphurous acid or chlorine. 

Invisible gaseous hydrochloric acid forms visible grayish-white 
fumes on coming into contact with air. This is due to its abstract- 
ing moisture from the air and dissolving in it, the fumes consisting 
of minute particles of solution of hydrochloric acid. The great 
readiness with which hydrochloric acid gas dissolves in water is 
strikingly demonstrated on opening a test-tube full of the gas 
under water; the latter rushes into and instantly fills the tube. 
If the water is tinged with blue litmus, the acid character of the 
gas is prettily shown at the same tinae. The test-tube, which 
should be perfectly dry, may be filled from the delivery-tube 
direct; for the gas is somewhat heavier than air and therefore 
readily displaces it. At low temperatures hydrochloric acid and 
water form a crystalline compound, HCl, 2H2O. 

Note. — The process, as described (p. 252), includes the use of 
as much sulphuric acid as is necessary for the production of the 
acid sodium sulphate, NaHSO^, which remains in the generating 
vessel. A hot solution of this residue, neutralized by sodium 
carbonate, filtered and set aside, yields normal sodium sulphate 
{Sodii Sulphas, U. S. P.), Glauber's Salt, Na^SO^lOHp, in the 
form of transparent, oblique, efflorescent prisms. 



2NaHS0, + Na,C03 

Sodium liydrogen Sodium" 
sulphate carbonate 



In the commercial preparation of sodium suli)hate tor tlio 
manufacture of sodium carbonate by the Leblanc process, the 



2Nn,S0, 


+ H.,0 


+ CO. 


Sodium 


Water 


Carbonie 


sulphate 




anhydride 



254 THE ACID RADICALS. 

propoitiuiis in which the sodium chloride and the sulphuric acid 
are employed are those required to form normal sodium sulphate 
and not acid sodium sulphate. To carry out this reaction a higher 
tem^Derature is necessary. 2NaCl+H2SO^=2HCl + Na2SO^. 

CHLORINE. 

Experiment 2. — To some drops of hydrochloric acid (that 
is, the common aqueous solution of the gas) add a few grains 
of black manganese oxide, and warm the mixture ; chloride is 
evolved, and may be recognized by its peculiar odor and by 
its highly irritating effect on the nose and air-passages. 

4HC1 + MnO^ = C\ + 2nfi + MnCl^ 

Chlorine water. — Liquor Chlori Compositus, the chlorine water 
of the U. S. P. is prepared by dissolving in water the gas produced 
by acting on potassium chlorate with hydrochloric acid diluted 
with its own weight of water. It contains some oxides of chlorine 
and potassium chloride. At ordinary temperatures, if fresh and 
thoroughly saturated, chlorine water contains about 0.4 percent, 
of chlorine. When chlorine water is exposed to daylight, the 
chlorine slowly decomposes water with production of hydrochloric 
acid and oxygen; hence the solution should be freshly prepared; 
it is best preserved in a green glass well-stoppered bottle in a cool 
and dark place. Chlorine passed into cold water yields crystals 
of chlorine hydrate, ClgSH^O, and these, when heated in a sealed 
tube under pressure, give an upper layer of chlorine water and a 
lower layer of liquid chlorine. 

Note. — To obtain the chlorine from other chlorides, such as 
sodium chloride, sulphuric acid, as well as black manganese oxide, 
must be added. It may be assumed that hydrochloric acid is first 
formed by the action of sulphuric acid on the sodium chloride, 
and that this then interacts with black manganese oxide and 
more sulphuric acid to form chlorine, manganous sulphate, and 
water. The following equations may represent these steps in the 
process : — 

2NaCl + H^SO, = Na^SO, + 2HC1, 

MnO, + 2HC1 + H^SO, = CI, + MnSO, + 211^0 ; 

or the whole may be included in one equation : 

2NaCl + MnO^ + 2H.3SO, = Na^SO, + MnSO, + 2H2O + Cl^ 



CHLORIDES. 255 

This reaction may occasionally have analytical interest, a very 
small quantity of chloride being recognizable by its means. But 
the following reaction is nearly always applicable for the detec- 
tion of this element, and leaves little to be desired in point of deli- 
cacy : — 

Analytical Reactions of Chlorides. 

To a drop of hydrochloric acid, or to a dilute solution of any 
other chloride, add solution of silver nitrate ; a white curdy precip- 
itate of silver chloride, AgCl, is produced. Pour away the super- 
natant liquid, add nitric acid, and boil ; the precipitate does not 
dissolve. Pour away the acid, and add dilute ammonia water; 
the precipitate quickly dissolves. Neutralize the solution by 
adding an acid ; the curdy precipitate again appears. 

The formation of this white precipitate, its appearance, insolu- 
bility in boiling nitric acid, solubility in ammonia water and repre- 
cipitation by an acid, form, in the known absence of bromide, abun- 
dant evidence of the presence of chloride. 

If free hydrochloric acid be present in a quantity in a solution, 
it will, in addition to the reaction with silver nitrate, give rise to 
strong effervescence on the addition of a carbonate, a chloride 
being formed. The chlorine in insoluble chlorides, such as calo- 
mel, white precipitate, etc. , may be detected by boiling with caus- 
tic alkali, filtering, acidulating the filtrate by means of nitric acid, 
and then adding the silver nitrate. 

Antidotes. — In cases of poisoning by hydrochloric acid, solution 
of sodium carbonate (common washing-soda) or a mixture of 
magnesia and water may be administered. 



QUESTIONS AND EXEECISES. 



Why does hydrochloric acid gas give visible fumes on coming into con- 
tact with air?— How much sodium chloride will be required to furnish 
one pound of chlorine ?— Give the analytical reactions of chlorides.— What 
antidotes may be administered in cases of poisoning by hydrochloric acid ? 



HYDROBROMIC ACID, HBr, AND OTHER BROMIDES. 

Bromine .--Source, Preparation and Properties. — The acid radical 
of hydrobromic acid and other bromides is bromine, V>v{Bromum, 
U. S. P.). Bromine occurs in nature in the form of bromides in 
sea-water and certain saline springs, and is prepared from the bit- 
tern, or residual liquors of salt works. It may be liberated from 



256 



THE ACID RADICALS. 



Fig. 38. 



bromides by a process similar to that employed for liberating 
chlorine from chlorides — that is, by heating with black manganese 
oxide and sulphuric acid {see note on p. 254) ; but is noAV largely 
obtained by liberating it from bromides by the action of chlorine. 
(Compare reaction, p. 257). It is dark-red volatile liquid of 
specific gravity, 2.99 to 3.0 at 15°C, and possessing an odor more 
irritating, if possible, than that of chlorine. — Its boiling point is 
63° C. (145.4° F.). Bromine in hydrobromic acid and the brom- 
ides, is univalent (Br^). Its atomic weight is 79.36, and its mole- 
cular formula is Br.^. 

Hydrobromic acid. — Hydrogen bromide, or hydrobromic acid, 
may be made by decomposing phosphorous tri -bromide or penta- 
bromide by means of water; PBr,+ 3H20=3HBr+H3P03, or 
PBr5+4H20==5HBr+H3POi. A small quantity is prepared by 

placing seven or eight drops 
of bromine at the bottom of 
a test-tube, putting in frag- 
ments of glass to the height 
of about an inch or two, then 
ten or eleven grains of red 
phosphorus, then another 
inch of glass, and finally a 
couple of inches of glass 
fragments slightly wet with 
water, a delivery-tube being 
fitted by means of a cork. 
The phosphorus combines 
readily, almost violently, 
with the bromine as soon as the vapor of the latter, aided by gentle 
heating, comes into contact with the phosphorus. The phos- 
phorus tri-bromide thus formed then suffers by decomposition by 
the water of the moist glass, hydrobromic and phosphorous acids 
being produced. The hydrobromic acid gas passes over (further 
heat being applied in the later stages of the operation) and may 
be led into water or ammonia water. The latter solution on evapo- 
ration yields ammonium bromide. 

Solution of hydrobromic acid may also be prepared by passing 
hydrogen sulphide through bromine covered with water, until all 
color has disappeared, and then distilling the mixture. 10Br„+ 




Preparation of hydrobromic acid. 



4H,S + 8H,0= 20HBr+ 2H,S0, 



S, 



A better method is that of 



Scott, who prepares pure solution of hydrobromic acid by passing 
purified sulphurous anhydride into water lying over a layer of 
bromine, until a homogeneous liquid, still slightly yellow from the 
presence of free bromine, is obtained ; and then distilling this 
liquid several times, so as to remove uncombined bromine and 
traces of sulphuric acid. Br^H- S0,+ 2H,,0= 2HBr+ H,SO,. For 
rapidly obtaining a solution of hydrobromic acid on a small scale, 
H. Marshall recommends the addition of sulphuric acid to a 



BROMIDES. • 257 

saturated solution of barium bromide, in a quantity nearly but not 
quite sufficient to precipitate the whole of the barium as sulphate, 
followed by filtration of the solution, and distillation. 

Hydrobromic acid, like hydrochloric acid, is monobasic. 

Acidum Hydrobromicum Dilutum, U. S. P., is prepared by the 
distillation of potassium bromide with concentrated phosphoric 
acid. Its specific gravity is 1.076, and it contains 10 percent, by 
weight of hydrogen bromide, HBr. 

Potassium Bromide, KBr, is very largely employed in pharmacy, 
and may be used in studying the reactions of bromides. The 
method of making the salt has been alluded to under the potas- 
sium salts (p. 81). 

Sodium Bromide crystallizes in anhydrous cubes, NaBr from 
solutions at 110° to 120° F. (43.3°-48.8° C), and in hydrous 
prisms, NaBr, 2H2O, at ordinary temperatures. 

Ammonium Bromide, NH^Br {Ammonii Bromidum, U. S. P.) 
may be made by neutralizing hydrobromic acid with ammonia : 
HBr+NH,0H=NH,Br4- H2O. It forms colorless crystals which 
may become slightly yellow on exposure to air. It is readily 
soluble in water, less so in alcohol, and sublimes when heated. 

Other bromides are seldom used ; they may be prepared in the 
way as the corresponding chlorides or iodides, which they closely 
resemble. 

Bromine Test Solution, U. S. P., (Bromine Water) 1 part in 100, 
is an aqueous solution, bromine being slightly soluble in water. 

liypobromites and Bromates, analogous to hypochlorites and 
chlorates, can easily be prepared. 

Bromates, occurring as impurity in bromides, are detected by 
dropping dilute sulphuric acid upon the salt ; a yellow color, 
due to free bromine, is produced immediately if bromates are 
present : — 



KBr + 


H^SO, = HBr + KHSO, 


[BrO^ + 


H^SO, = HBr03 + KHSO, 


5HBr + 


HBr03= 3Br, -f SH^O 



Analytical Reactions of Bromides. 

1. To a few drops of a solution of a bromide (KBr or 
N2H^Br) add solution of silver nitrate ; a yellowish-white pre- 
cipitate of silver bromide, AgBr, is produced. Treat the precipi- 
tate successively with nitric acid and dilute ammonia water, 
as described under silver chloride ; it is dissolved by the 
ammonia solution, but somewhat less readily than the silver 
chloride. 

2. To a solution of a bromide add a few drops of chlorine 
water, or pass in some bubbles of chlorine gas ; then add a 

17 



258 THE ACID RADICALS. 

few drops of chloroform, or ether, or carbon disulphide, shake 
the mixture, and set the test-tube aside ; the chlorine displaces 
the bromine, which is dissolved by the chloroform, ether, or 
carbon disulphide (the solution falling to the bottom of the 
tube in the case of the heavy chloroform or carbon sulphide, 
or rising to the top in the case of the light ether). The solu- 
tion of bromine has a distinct yellow, or reddish-yellow, or red 
color, according to the amount of bromine present in it. 
2KBr -f CI, = 2KC1 + Br,. 

Note. — This reaction serves for the isolation of bromine when 
mixed with many other substances. Excess of chlorine must be 
avoided, as colorless bromine chlorine is then formed. Iodides 
give a somewhat similar appearance; the absence of iodine must 
therefore be ensured by a process given in the next section. The 
above solution in chloroform or ether may be removed from the 
tube by drawing it up into 2i pipette (small pipe — a narrow glass- 
tube, usually having a bulb or expanded portion in the middle); 
the bromine which it contains may be converted into relatively 
non- volatile salts by the addition of a drop of solution of potassium 
or sodium hydroxide ; the chloroform or ether may then be removed 
by evaporation, and the residue tested as described in the next 
paragraph. 

. 3. Liberate bromine from a bromide by the cautious addi- 
tion of chlorine or chlorine water, then add a few drops of 
cold mucilage of starch ; a yellow combination of bromine and 
starch, termed "starch bromide," is formed. 

Bromine may also be liberated from bromides by adding concen- 
trated sulphuric acid and some black manganese oxide, and gently 
heating. Even sulphuric acid alone, if concentrated, liberates 
bromine from a bromide, the hydrogen of the hydrobromic acid 
combining to some extent with the oxygen of the sulphuric acid, 
and the latter being reduced to sulphurous anhydride : — 

2KBr + 2H2SO, = K2SO, + Br, + SO, + 2H,0 



HYDRIODIC ACID, HI, AND OTHER IODIDES. 

Iodine --Source. — The acid radicals of hydriodic acid and other 
iodides is iodine, I. Iodine occurs in nature in the form of iodides, 
in sea-water. Sea-weeds, sponges, and other marine organisms, 
which derive much of their nourishment from sea- water, store up 
iodides in their tissues ; and it is from the ashes of these that sup- 
plies of iodine {lodum, U. S. P.), are obtained. Iodine also 
occurs in the form of iodates in crude sodium nitrate. 



IODIDES. 259 

Preparation. — The sea-weed ash, or kelp, is treated with water, 
insoluble matter thrown away, and the decanted liquid evaporated 
and set aside to allow of the deposition of most of the sodium and 
potassium sulphates, carbonates, and chlorides. The residual 
liquor is treated with excess of sulphuric acid, which causes evolu- 
tion of carbonic anhydride and of sulphurous anhydride or hydro- 
gen sulphide, deposition of sulphur and more sodium sulphate, and 
formation of hydriodic acid. To the decanted liquid black man- 
ganese oxide is added, and the mixture is then slowly distilled; 
the iodine sublimes and is afterwards purified by resublimation. 

2HI + MnO^ + H2SO4 = MnSO^ + 2ILfi^\ 

Properties. — Iodine is a crystalline purplish-black solid ; its 
vapor, readily seen on heating a fragment in a test-tube, is dark 
violet. The vapor is irritating to the lungs ; but a trace may be 
inhaled with safety. Iodine melts at 237. 2° F. (114° C), boils at 
about 392° F. (200° C), the first portions containing any cyanogen 
iodide that may be present. The latter substance, which is rarely 
present in iodine, forms slender, colorless prisms, which emit a pun- 
gent odor. 

Solution of Iodine. — Iodine is slightly soluble in water (iodine- 
water), and readily soluble in an aqueous solution of potassium 
iodide.^ Five parts of iodine and ten of potassium iodide, dis- 
solved in sufiicient distilled water to make 100 parts, form Liquor 
lodi Compositus, U. S. P. Tinctura lodi, U. S. P. is an alcoholic 
preparation of difierent strength, 4 parts of iodine and 4 of potas- 
sium iodide, rubbed with 12 of glycerin, and 80 of benzoinated 
lard, form Unguentum lodi, U. S. P. 

Iodine combines with sulphur, forming an unstable grayish- 
black, solid iodide, S^I^, having a radiated crystalline structure 
(Sulphuris lodidum, U. S. P.). 

Iodine in hydriodic acid and the iodides, is univalent (I^). The 
atomic weight of iodine is 125.9 ; its molecular formula is I^. 

Hydriodic Acid. — Hydrogen iodide, or hydriodic acid, is a heavy 
colorless gas. A solution of it in water may be made by passing 
hydrogen sulphide into water in which iodine is suspended, the 
chief reaction being : — H.^S -f I^ = S -f 2HI. See the analogous 
reaction for HBr, p. 257. 

Hydriodic acid may also be prepared by placing twenty parts 
of iodine and two of water in a retort, the neck of which points 
upward and the end of the neck of which is connected by a glass 
tube with a bottle or other vessel containing a little water. Into 
the tubulure of the retort there is passed (at first a drop at a time) 

1 Iodine forms differently colored solutions with different solvents: ('.(7. 
the solution in watei-, alcohol, ether, or aqueous solution of potassium 
iodide is brown, while the solution in chloroform, benzene, or carbon 
disulphide, is violet. 



I 



260 THE ACID RADICALS. 

a mixture of one part of red phosphorus with two of water. 
Abundance of hydriodic acid is evolved on the gentle application 
of heat, and dissolves in the water in the receiver. Phosphoric 
acid remains.— P, + lOI^ ^ IGH^O = 20HI + 4H3PO,. See 
analogous reaction for H Br, p. 256. 

The official acid {Acidum Hydriodicum Diluhnn) is prepared by 
the action of tartaric acid, in dilute alcoholic solution, on potas- 
sium iodide in presence of a small quantity of potassium hypo- 
phosphite, the alcohol being subsequently removed. The function 
of the hypophosphite is to prevent the liberation of iodine through 
oxidation of part of the hydriodic acid. 

Sijrupus Acidi Hydriodici, U. S. P., contains about 1 percent, 
of hydrogen iodide. 

Potassium Iodide, KI, is largely used in medicine, and is a con- 
venient salt on which to experiment in studying the reactions of 
iodides. 

Nitrogen Iodide is formed Avhen excess of aqueous ammonia is 
added to a solution of iodine in potassium iodide. 

Analytical Reactions of Iodides. 

1. To a few drops of an aqueous solution of au iodide {e.g. 
KI) add solution of silver nitrate ; a pale yellow precipitate 
of silver iodide, Agl, is produced. Pour away the supernatant 
liquid, and treat the precipitate with nitric acid; it is not dis- 
solved. Pour away the acid, and then add ammonia water; 
the precipitate is almost unchanged. 

2. Liberate iodine from an iodide by the cautious addition 
of chlorine water, then add starch mucilage; a deepblue com- 
bination ofiodine and starch, termed "starch iodide," is formed. 

This reaction is very delicate and characteristic. Heat decom- 
poses the blue compound. Excess of chlorine must be avoided, or a 
solution of iodic acid will be produced, which is colorless. Nitrous 
acid, or a nitrite acidulated with sulphuric acid, may be used instead 
of chlorine. Concentrated sulphuric acid also liberates iodine 
from iodides, the hydrogen of the hydriodic acid first produced 
uniting with the oxygen of the sulphuric acid whereby the latter 
is reduced to sulphurous anhydride, or even to hydrogen sul- 
phide. 

In testing bromine for the presence of iodine, the bromine must 
be nearly all converted into hydrobromic acid by means of dilute 
solution of sulphurous acid {see p. 256, Scott's process) or be nearly 
removed by addition of sodium hydroxide, before the starch of 
mucilage is added. 

Ozone {0^. — Papers soaked in starch mucilage containing potas- 
sium iodide form a test for free chlorine and nitrous acid, and are 



IODIDES. 261 

also employed by meteorologists to detect an allotropic and very 
active form of oxygen, termed by Schonbein ozone (from 6Cw, ozo, 
I smell), which also liberates iodine from potassium iodide with 
formation of starch iodide. Ozone is supposed to occur normally 
in the atmosphere, the salubrity or insalubrity of which is said to 
be dependent to some extent on its presence or absence. The 
possible occurrence in the air of nitrous or other oxidizing gases 
(as well as ozone) renders the starch test untrustworthy. Houzeau 
proposed to test for ozone by exposing litmus-paper of a neutral 
tint soaked in a dilute solution of potassium iodide : the alkali set 
free by the action of the ozone turns the paper blue. The same 
paper without iodide would indicate the extent to which the effect 
might be due to ammonia. Ozone, or rather, ozonized air, is pro- 
duced artificially in large quantities by passing air through a box 
(Beane's Ozone generator) in which it is exposed to the silent 
electrical discharge. In the latter operation condensation of the 
volume of air, or rather, of the oxygen in the air, occurs. Ozone 
is also produced in small quantity when phosphorus undergoes 
slow oxidation in moist air, some hydrogen peroxide and ammo- 
nium nitrate being formed at the same time. Ozone is a powerful 
bleaching, disinfecting and oxidizing agent ; it is very sparingly 
soluble in water, but soluble in oils of turpentine and cinnamon, 
and in some other liquids. Its odor is charcteristic. From experi- 
ments that have been made by Soret on the specific gravity of 
ozone, its molecular formula seems to be O3, that of ordinary oxy- 
gen being O2. 

3. To a neutral aqueous solution of an iodide add a solu- 
tion containing one part of cupric sulphate and two and a half 
parts of ferrous sulphate, and well shake ; a dirty-white pre- 
cipitate of cuprous iodide, Cul, is produced. 

2KI + 2CuS0, + 2FeS0, = 2CuI + K^SO, + FeXS0j3 

Or to the liquid containing an iodide add solution of cupric 
sulphate and some solution of sulphurous acid, and warm the 
mixture ; cuprous iodide is again produced. 

2KI + 2CuS0,+ H,S03+ ^fi = 2CulH-2KHSO,+ H,SO, 

Separation of Chlorides, Bromides, and Iodides. — Chlorides and 
bromides are not precipitated by curpric sulphate ; the above 
reaction is useful, therefore, in removing iodine from a solution 
in which chlorides and bromides may also be present. The total 
removal of iodine by the former of the two modifications of the 
process is ensured by following up the addition of the curpric and 
ferrous sulphates by adding a few drops of solution of potassium 
or sodium hydroxide, any acid which might retain cuprous iodide 



i| 



262 THE ACID RADICALS. 

in solution being thereby neutralized ; ferric or ferrous hydroxide, 
precipitated at the same time, not affecting the reaction. Occa- 
sionally, too, it may be necessary to repeat the process with the 
filtrate before the last traces of iodine are removed. The second 
modification of the process is, on the whole, to be preferred. 

Hart's Test. — (If nitrates, chlorates, bromates, or iodates are pres- 
ent, it is necessary to fuse the substance with a little sodium car- 
bonate and charcoal to reduce them. If the chlorine, bromine, and 
iodine, are united with silver, it is best to fuse with sodium carbonate 
and extract with water, although with iodine and bromine this is not 
absolutely necessary.) The substance is placed in the flask shown 
in the figure given in the section on the quantitative analysis of 
manganese oxide {see Index), with some water and a few drops of 
solution of ferric sulphate. Into the bulbs a few drops of dilute 
starch mucilage are poured. The bulbs are kept cold by immer- 
sing in water in a beaker. The contents of the flask are then 
boiled, and if iodine is present the starch is colored blue. This 
test is extremely delicate. If iodine is found, the cork and the 
bulb tube are removed, and the solution boiled until, on testing 
again in the same way, no more iodine is found. If much iodine 
is present, it is necessary to add more ferric sulphate solution. 
The bulb tube is now cleaned, charged with a few drops of water 
and a drop or two of chloroform, and a very small crystal of 
potassium permanganate is added to the solution in the flask. 
The contents of the flask are boiled again, and if bromine is 
present the chloroform becomes red. The tube is now removed, 
and more potassium permanganate and ferric sulphate added little 
by little, the mixture being boiled between each addition until 
the bromine has all been driven off". A few drops of alcohol are 
added to the contents of the flash to decolorize any excess of per- 
manganate, and, after filtration, chlorine is tested for in the filtrate 
by means of silver nitrate. 

Detection of Chloride in presence of Bromide or Iodide or 
both. — To a small quantity of the mixed solution add excess 
of silver nitrate in presence of nitric acid, and wash the pre- 
cipitate once or twice with water by decantation, Then pour 
upon the precipitate 1 Cc. of a very dilute solution of potas- 
sium iodide (1 part in 1000 of water), add a few drops of 
dilute nitric acid, allow to stand in the cold for an hour with 
occasional shaking, and filter. Divide the filtrate into two 
parts, and add silver nitrate to one part and a drop of diluted 
chlorine water to the other. If the silver nitrate produces a 
white precipitate ^ and the chlorine does not liberate either 

^Silver nitrate produces a precipitate in any case, which may con- 
sist of silver chloride, bromide, or iodide and may, therefore, be pure 
white, yellowish, or yellow. 



IODIDES. 263 

bromine or iodine, then the original precipitate contained sil- 
ver chloride. 

The action of the potassium iodide on the silver chloride is repre- 
sented by the equation : — AgCl -(- KI = Agl + KCl. If there is 
enough silver chloride present in the original precipitate, all the 
added potassium iodide is converted into potassium chloride and 
it is the latter which gives the white precipitate on the addition 
of silver nitrate. If the chlorine water liberates bromine or iodine, 
this shows (when not more the 1 Cc. of the 1 in 1000 potassium 
iodide has been used) that distinctly less than 1 milligramme of 
silver chloride, and probably none at all, was present. 

Chlorides may also be detected in presence of bromides and 
iodides by taking advantage of the formation of chlorochromic 
anhydride (p. 169) and the non-occurrence of corresponding com- 
pounds of bromine or iodine, as follows: — 

To a solution of a mixture of an iodide with a bromide and 
a chloride add a concentrated solution of sodium sulphite, then 
a reagent prepared by mixing equal volumes of sulphuric acid 
and saturated solution of cupric sulphate, until no further pre- 
cipitation of cuprous iodide occurs. Next add solution sodium 
hydroxide to remove the excess of copper, filter, and evaporate 
to dryness. Transfer the dried residue, together with an equal 
bulk of potassium dichromate, to a dry test-tube fitted with a 
delivery-tube, or to a small retort, and cover the. mixture with 
sulphuric acid. Distil into water. Chromic anhydride and 
hydrochloric and hydrobromic acids are liberated by the sul- 
phuric acid, and interacting with one another, form chloro- 
chromic anhydride, together with free bromine and chlorine. 

Cr03 -f 2HC1 = CrO^Cl, + H.p 
2Cr03 + 6HBr + 3H,S0,= Cr^CSOJ^ + 3Br, + 6H.p 
2Cr03 + 6HC1 + 3H,S0, = Cr,(S0j3 + 3C1, + 6H,0 

The chlorochromic anhydride is decomposed by the excess of 
water into which it distils, giving rise to anhydrochromic acid, 
which imparts its orange color to the liquid, and hvdrochloric 
acid, thus : 2QrOfi\ + SH^O = H^Crp, + 4HC1. The chlorine 
which is produced in the reaction escapes, and the bromine is dis- 
solved by water. The colored liquid is then shaken Avith chloro- 
form, which removes theobromine, indicating bromides in the 
original substance ; a yellow or orange color remaining is due to 
anhydrochromic acid, indicating chlorides in the orginal substance. 
Or ammonia may be added to the distillate ; the color due to 
bromine is thereby entirely removed, while the yellow color of 
ammonium chromate remains. 



264 THE ACID RADICALS. 

Instead of eliminating the iodine as cuprous iodide, it may be 
expelled in vapor (obvious enough by its color and odor) by fusing 
the dry mixture of the salts with excess of powdered potassium 
dichromate. The residue, broken into small fragments, may then 
be distilled with sulphuric acid for the detection of the bromine 
and chlorine. 



SK^Cr^O, + 6KI = SK^CrO^ + Cr^Og + 31 



4. Iodides have been shown to be useful in testing for mer- 
curic salts (.see the Mercury reactions, p. 218); a mercuric salt 
(corrosive sublimate, for example) may therefore be used in 
testing for iodides, a scarlet precipitate of mercuric iodide, 
Hgl^, being produced. 

This reaction may be employed where comparatively large 
quantities of an iodide are present ; but its usefulness in analysis 
is limited by the fact that the precipitate is soluble in excess of 
the dissolved iodide, or in excess of the mercuric solution. The 
color of the precipitate and its insolubility in water distinguish it 
from mercuric chloride, bromide, and cyanide, which are white 
soluble salts. 

5. Iodides have also been shown to be useful in testing for 
lead salts (see the Lead reactions, p. 224); similarly a lead 
salt (acetate, for example) may be used in testing for iodides 
in solutions which are either neutral or faintly acid with acetic 
acid, a yellow precipitate of lead iodide, Pbl^, soluble in hot 
w^ater and crystallizing in yellow scales on cooling, being 
produced. 

Lead chloride, bromide, and cyanide are white; hence the above 
reaction may occasionally be useful in distinguishing iodides 
from chlorides, bromides or cyanides. But lead iodide is slightly 
soluble in cold water; hence small quantities of iodides cannot be 
detected by means of this reaction. (For lodates, see p. 280). 

Analogies between Chlorine, Bromine, Iodine and their Com- 
pounds. — These elements form a natural group or family, the 
members of which are closely related and exhibit a distinct gra- 
dation in physical properties. Thus chlorine is a gas and iodine 
a solid, while bromine occupies the intermediate liquid condition. 
The atomic weight of bromine is nearly midway between those of 
chlorine and iodine. The specific gravity of liquid chlorine is 
1.33, of iodine 4. 95, while that of bromine is nearly 3. Liquid 
chlorine is transparent, iodine opaque, bromine intermediate. 
The crystalline forms of the chloride, bromide and iodide of the 
same metal are commonly identical. One volume of either element 
in the gaseous state combines with an equal volume of hydrogen 



CYANIDES. 265 

(at the same temperature and pressure) to form two volumes of a 
gaseous acid, very soluble in water (hydrochloric acid, hydrobromic 
acid, hydriodic acid). By their union with metals, chlorine, 
bromine, and iodine form salts of which sodium chloride, bromide 
and iodide may be taken as types. On this account they have been 
called the halogens {i.e., salt producers), and the salts are called 
haloid salts (from a/f , hals, sea-salt, and eldog, edios, likeness). 



QUESTIONS AND EXEECISES. 



State the method by which bromine is obtained from its natural com- 
pounds. — Mention the properties of bromine. — How may potassium and 
ammonium bromides be made? — By what reagents may bromides be dis- 
tinguished from chlorides? — Whence is iodine obtained?— By what pro- 
cess is iodine isolated ? — State the properties of iodine.— What is the nature 
of sulphur iodide ? — Give the analytical reactions of iodides. — ^What three 
substances may, indirectly, be detected by a mixture of potassium iodide 
and starch mucilage ? — Describe two methods by which iodides may be 
removed from a solution containing chlorides and bromides. 



HYDROCYANIC ACID, HCN, AND OTHER CYANIDES. 

The acid radical of hydrocyanic acid and other cyanides is a 
compound group, the cyanogen radical, CN, (or shortly, Cy). It 
is so named from Kvavog, kuanos, blue, and x^i^vato, gennao, I gener- 
ate, in allusion to its ;f)rominent chemical character for forming, 
with certain iron compounds, the different varieties of Prussian 
blue. It was from Prussian blue that Scheele, in 1782, tirst 
obtained what we now, from our knowledge of its composition, 
call hydrocyanic acid, HCN or HCy, also called prussic acid. 
Cyanogen, C^<^, was isolated by Gay-Lussac in 1814, and was the 
first compound radical distinctly proved to exist. 

Sources, e^c— Certain compounds containing the cyanogen radi- 
cal occur in nature, and others can easily be prepared. Ammo- 
nium cyanide is found in small quantities among the gases of iron 
furnaces, and is produced to a slight extent in distilling coal for 
gas. In the preparation of potassium ferrocyanide the cyanogen 
radical is formed abundantly by heating animal refuse containing 
nitrogen, such as the scrapings of horns, hoofs, and hides (5 ])arts), 
with crude potassium carbonate (2 parts) and waste iron (tilings, 
etc.) in a covered iron pot. The residual mass, which contains 
potassium cyanide, but no ferrocyanide, is boiled with water, the 
mixture filtered, and the filtrate evaporated and set aside for crys- 
tals of ferrocyanide to form. The cyanogen, produced from the 
carbon and nitrogen of the animal matter, unites with tlie potas- 



11 



iv 



266 THE ACID RADICALS. 

slum to form potassium cyanide and this afterward, on boiling 
with water, interacts with iron sulphides (produced by the inter- 
action of the iron with sulphur occurring in the nitrogenous 
organic matters, and as sulphate in the crude potassium car- 
bonate) to form what is often termed yellow prussiate of pot- 
ash, Potassium Ferrocyanide, Poiasii Ferrocijanidum, U. S. P., 
K^FeCgjNgSHgO, a compound occurring in four-sided tabular yel- 
low crystals. This salt contains the elements of cyanogen; yet is not 
a cyanide, but a ferrocyanide. It is not poisonous, and is other- 
wise different from cyanides ; it will be further noticed subsequently. 
From this salt all cyanides are directly or indirectly prepared. 

Potassium cyanide, KCN or KCy, the commonest cyanide, may 
be obtained by heating potassium ferrocyanide to redness until 
gas (chiefly nitrogen) is no longer evolved and iron carbide settles 
to the bottom of the molten mass of almost pure cyanide. The 
product, carefully poured off and cooled, is an opaque crystalline 
mass, Potasii Cyanidum, U. S. P., containing about 95 percent, 
of potassium cyanide. It may also be produced by fusing eight 
parts of potassium ferrocyanide with three of potassium carbonate 
in a crucible; carbonic anhydride is evolved, iron is set free, and 
potassium cyanate, KCNO, is formed, as well as potassium 
cyanide: — 

K.FeCgNg + K2CO3 = 5KCN + KCNO + Fe + CO^ 

Mercuric cyanide is produced in crystals by dissolving 1 part of 
potassium ferrocyanide in 15 parts of boiling water, adding 2 parts 
of mercuric sulphate, keeping the whole hot for ten to fifteen 
minutes, and then filtering and setting aside to cool. Besides 
mercuric cyanide, IIg(CISJ)2, ferric sulphate and potassium sulph- 
ate are formed, and mercury is set free. Any excess of ferrocyan- 
ide gives Prussian blue by interaction with the ferric sulphate. 

Mercuric cyanide is exceptional in some of its analytical reac- 
tions, both as a mercuric salt and as a cyanide. Thus its solution 
does not give any precipitate with potassium iodide, {see reaction 
1 of Mercuric Salts, p. 218) unless a drop of hydrochloric acid has 
previously been added ; neither does it yield the usual yellow and 
white precipitates Avith potassium hydroxide and with ammonia 
water respectively. Similarly it does not give the silver nitrate 
reaction for cyanides {see reaction 1, p. 228). 

Cyanogen, Q^^, may be isolated by heating mercuric cyanide, 
Hg(CN)2, or silver cyanide, AgCN. A small flame of cyanogen 
may be obtained by heating a few crystals of mercuric cyanide in 
a short piece of glass tubing closed at one end, and applying a 
light to the other end as soon as evolution of gas commences ; 
brown paracyanogen (CN)„, and mercury are also produced. In 
the case of silver cyanide metallic silver remains. Cyanogen is 
a colorless gas which burns with a beautiful peach-blossom colored 
flame. 



CYANIDES. 267 

Diluted Hydrocyanic Acid. 

Experiment. — Dissolve 2 or 3 grains of potassium ferro- 
cyanide in 5 or 6 times its weight of water in a test-tube, add 
a few drops of sulphuric acid and boil the mixture, conveying 
the evolved gas through a bent glass tube (adapted to the test- 
tube by means of a cork) into another test-tube containing a 
little water ; the product is a dilute solution of hydrocyanic 
acid. The official solution, Acidum Hydrocyanicum Dilutum, 
is prepared by interaction of silver cyanide and dilute hydro- 
chloric acid. It is a colorless liquid with a characteristic 
odor and is exceedingly poisonous. It contains 2 percent, by 
weight of hydrogen cyanide, HCN. 

2K,FeC,Ng + 6H^S0, = FeK^FeCgN, -f 6KHS0, + 6HCN 

To prepare a larger quantity proceed as follows, carrying out 
the operation in a well ventilated fume-cupboard : — Dissolve 2|^ 
ounces of potassium ferrocyanide in 10 ounces of water, add one 
fluid ounce of sulphuric acid previously diluted with 4 ounces of 
water and cooled. Put the solution into a flask or other suitable 
apparatus of glass or earthenware, to which are attached a conden- 
ser and a receiver arranged for distillation {see p. 130) ; and 
having put 8 ounces of distilled water into the receiver, and pro- 
vided efiicient means for keeping the condenser and receiver cold, 
apply heat to the flask, until by slow distillation the liquid in the 
receiver is increased to 17 fluid ounces. '^ Add to this 3 ounces of 
distilled water, or as much as may be sufficient to bring the acid 
to the required concentration. The end of the condenser, or an 
attached tube, should pass quite into the receiver. 

The residue from this reaction is acid potassium sulphate, 
KHSO4, which remains in solution, and potassium ferrous ferro- 
cyanide, FeKgFeCgNg, an insoluble powder sometimes termed 
Everitt's salt, from the name of the chemist who first made out 
the nature of the interaction. The latter compound becomes bluish 
green during the operation, owing to absorption of oxygen. 

Pure anhydrous hydrocyanic acid is a colorless, highly volatile, 
intensely poisonous liquid, solidifying when cooled to a low tem- 
perature. It may be made by passing hydrogen sulphide over 
mercuric cyanide. The oflftcial solution of the acid is moderately 
stable, but is said to be rendered more so by the presence of a 
minute trace of sulphuric or hydrochloric acid. A more concen- 

^ This operation is peculiarly liable to those sudden and tumultuous 
evolutions of vapor, or "bumping." which often interfere with successful 
distillation. Such bumping- may usually be prevented and quiet ebullition 
ensured by placing in the liquid, before beginning to heat it, a few small 
fragments of unglazed earthenware, such as tobacco-pipe stem. 



268 THE ACID RADICALS. 

trated acid is liable to take up the elements of water and yield 
ammonium formate, NH^CHO^. Solutions of hydrocyanic acid 
often become brown by formation of what is, apparently, paracy- 
anogen, (CISr)« . According to Williams, aqueous hydrocyanic 
acid containing 20 percent, of glycerin can be kept for an almost 
indefinite length of time. The official acid should be preserved 
in well-stoppered bottles tied over with impervious tissue and 
kept inverted, when not in use, in a cool dark place. Unless such 
precautions are adopted, the solution rapidly becomes less concen- 
trated by escape of gaseous hydrocyanic acid. 

Hydrocyanic acid also occurs in cherry-laurel water and bitter- 
almond water. ^ 

The methods of determining the concentration of hydrocyanic 
acid solutions will be given in the chapter on volumetric and 
gravimetric quantitative analysis. The volumetric method is 
based on the formation of silver cyanide and its solubility in 
solution of alkali-metal cyanides, as described in reaction 1, below. 
The hydrocyanic acid used in pharmacy is extremely liable to varia- 
tion in strength. It should frequently be tested volumetrically. 

Analytical Reactions of Cyanide. 

1. To a few drops of the hydrocyanic acid solution pro- 
duced in the foregoing experiment, or to a solution of any 
cyanide (except mercuric cyanide), add excess of solution of 
silver nitrate; a white precipitate of silver cyanide, AgCN, 
{Argenti Cyanidum, U. S. P.), is produced. When the precipi- 
tate has subsided, pour away the supernatant liquid and place 
half of the residue in another test-tube : to one portion add 
nitric acid, and notice that the precipitate does not dissolve ; 
to the other add ammonia water, and observe that the precipi- 
tate, though soluble, dissolves somewhat slowly. (Silver 
chloride, which is also white, is readily soluble in ammonia.) 
Silver cyanide dissolves in solutions of cyanides of alkali- 
metals, soluble double cyanides being formed ( 6.(7., KCN,AgCN, 
or KAg(CN),). Silver cyanides also dissolves in hot concen- 
trated nitric acid. 

Solubility of precipitates in concentrated solutions of salts. — Silver 
cyanide and many other precipitates insoluble in acids (or in 
alkalies) are often soluble in the saline liquids formed by the ad- 
dition of acids and alkalies to each other. Hence the precaution of 
adding the latter reagents to separate portions of a precipitate 

^ Traces are formed when an electric current passes between carbon 
poles in slightly moist air (Dewar); also during the action of nitric or 
nitrous acid on sugar, caramel, or finely divided charcoal. 



CYANIDES. 269 

when examining its solubility, or of not adding the one until the 
other has been poured away. 

Hydrocyanic acid and other cyanides may be detected in the pres- 
ence of potassium ferrocyanide by distilling with a large excess of 
sodium bicarbonate and testing the distillate for hydrocyanic acid. 
In the case of mercuric cyanide it is necessary to add a little 
hydrogen sulphide. 

2. To a dilute solution of hydrocyanic acid, or of a soluble 
cyanide (except mercuric cyanide), add a few drops each of 
solutions of a ferrous and of a ferric salt (ferrous sulphate 
and ferric chloride); to the mixture add potassium or sodium 
hydroxide, magnesia, or sodium carbonate, and then excess 
of hydrochloric acid; a precipitate of Prussian blue remains. 
The decompositions may be traced in the following equations : — 



HCN + 


KOH = 


KCN + 


H,0 


2KCN + 


FeSO = 


FeC.N, + 


K,SO, 


4KCN + 


FeC^N, = 


K^FeaK 




3K,FeCA-|- 


4FeCl3 = 


12KC1 -f- 


Fe,(FeCA) 



The test depends on the conversion of the cyanogen radical of 
the cyanide into ferrocyanogen by aid of the iron of a ferrous salt, 
and the combination of the ferrocyanogen, so produced, with the 
iron of a ferric salt. 

3. To a solution of hydrocyanic acid add ammonia water 
and yellow ammonium hydrosulphide, and evaporate the 
liquid nearly or quite to dryness in a small dish, occasionally 
adding ammonia till the excess of ammonium hydrosulphide is 
decomposed ; add water and acidulate the liquid with hydro- 
chloric acid, and then add a drop of solution of a ferric salt; 
a blood-red solution of ferric thiocyanate will be formed. ^ 

This is a very delicate reaction. Some free sulphur in the ^jtj^ 

yellow ammonium hydrosulphide unites with the alkali-metal fj!i| 

cyanide and forms thiocyanate (NH.CN + S - NH.SCN). If the •? ^^' 

liquid has not been evaporated far enough, ammonium hydro- 
sulphide may still be present, and give black ferrous sulphide on 
the addition of the ferric salt, hence the acidulation prior to the 
addition of the ferric salt. 

Hydrocyanic acid in the blood. — According to Buchner, the 
blood of animals poisoned by hydrocyanic acid, instead of coagu- 
lating as usual, remains liquid and of a clear cherry-red color for 
several days. In one case he obtained the reactions of the acid on 
diluting and distilling the blood fifteen days after death, and 
applying the usual reagents to the distillate. Aqueous solution 
of hydrogen peroxide changes such blood to a deep-brown color. 



270 THE ACID RADICALS. 

Schonbein's test for hydrocyanic acid is said to be extremely 
delicate. Filter-paper is soaked in a solution of 3 parts of 
guaiaciim resin in 100 of alcohol. A strip of this paper is dipped 
in a solution of 1 part of cupric sulphate in 50 of water; a little 
of the suspected solution is placed on this paper and exposed 
to the air; the paper immediately turns blue if hydrocyanic acid 
be present. Or the paper may be placed over the mouth of an 
open bottle of medicine supposed to contain hydrocyanic acid, or 
may be otherwise exposed to the vapor of a suspected liquid. 

Antidote. — A mixture of ferrous sulphate, solution of ferric 
chloride, and either magnesia or sodium carbonate is the recog- 
nized antidote in cases of poisoning by hydrocyanic acid or potas- 
sium cyanide. In such an alkaline mixture the poisonous cyanide, 
by interaction with ferrous hydroxide, is at once converted into 
innocuous potassium or other ferrocyanide: should the mixture 
become acid, the ferric salt present interacts wdth the soluble 
ferrocyanide forming insoluble Prussian blue Avhich is also inert. 
From the rapidity of the action of these poisons, however, there is 
seldom time to prepare an antidote. Emetics, the stomach-pump, 
or stomach-siphon, the application of a stream of cold water to 
the spine, and the above antidote, form the usual treatment. 



QUESTJIONS AND EXERCISES. 

Write a paragraph on the discovery of hydrocyanic acid and of cyano- 
gen. — Mention the source of the cyanogen of cyanides. — How is potass- 
ium ferrocyanide prepared ?— What is the formula of potassium ferro- 
cyanide ? — ^Is potassium ferrocyanide poisonous ? — Write an equation 
expressive of the reaction which ensues when potassium ferrocyanide and 
carbonate are brought together at a high temperature. — What are the 
properties of cyanogen? — How may it be obtained in a pure condition? 
— How is mercuric cyanide perpared ? — What other substances and second- 
ary products are formed at the same time ? — ^How much hydrocyanic 
acid is contained in the official Acichun Hydrocyanicum BUutum f — Give 
details of the preparation of hydrocyanic acid, and an equation represent- 
ing the reaction. — State the proportion of water that must be added to an 
aqueous solution containing 15 percent, of hydrocyanic acid to reduce 
the strength to 2 percent. Ans., 6^ to 1. — What are the characters of pure 
undiluted hydrocyanic, acid? — How may it be obtained ?— Enumerate the 
test for cyanides, giving equations. — Explain the action of the best anti- 
dote in cases of poisoning by hydrocyanic acid or potassium cyanide. 
Show how it acts in alkaline and acid solutions respectively. 



NITRIC ACID, HNO3, AND OTHER NITRATES. 

Sources. — Nitrogen peroxide, N^O^, is formed to some extent in 
the atmosphere by the combination of nitrogen and oxygen under 
the influence of the powerful electrical discharges during thunder- 
storms. This oxide undergoes further oxidation in presence of 



NITRATES. 271 

water; and with ammonia, which is always a constituent of the 
atmosphere, it forms ammonium nitrate. The nitrates found in rain 
no doubt originate partly or wholly in this manner. The oxidation 
of ammonia and of the nitrogenous constituents of animal and vege- 
table matters in the soil, favored by darkness by the presence of cal- 
cium carbonate, and especially by the presence of the nitrifying 
organisms, results in the production of nitrates. Hence nitrates 
are commonly met with in natural waters, and in soils and the 
juices of plants. In the concentrated plant juices, termed medi- 
cinal ''Extracts," small prismatic crystals of potassium nitrate 
may occasionally be observed. (The cubical crystals often met 
with in extracts are potassium chloride.) Nitric acid and other 
nitrates are prepared from potassium and sodium nitrates, which, 
in turn are obtained from the surface layers of the soil of tropical 
countries. Potassium nitrate (or prismatic nitre, from the form of 
its crystals), is produced in and about the villages of India. The 
natives simply scrape the surface of waste grounds, mud-heaps, 
banks, and other spots Avhere a slight incrustation indicates the 
presence of appreciable quantities of nitre, mix the scrapings with 
wood-ashes, containing potassium carbonate (to decompose the 
calcium nitrate always present), digest the mixture in water, and 
evaporate the liquor. The immediate product is purified by care- 
ful recrystallizations, and is sent into commerce in the form of 
white crystalline masses or fragments of striated six-sided prisms 
{Potassii Nitras U. S. P.). Besides its use in medicine, it is 
employed in very large quantities in the manufacture of gunpowder. 
Potassium nitrate is also largely prepared by the interaction of 
potassium chloride and sodium nitrate. Sodium Nitrate occurs in 
deposits from 3 inches to 3 yards in thickness on and near the sur- 
face, and at any depth down to about 30 feet, in many parts of 
Peru, Bolivia, and Chili, but more especially in the district of . 
Atacama. The mineral is termed caliche, and commonly contains h ;, 

50 percent, of sodium nitrate. The latter is distinguished as Chili , | !j 

saltpetre or Chili nitre, or (from the form of its crystals — obtuse ^ ;'' ,• 

rhombohedra, not cubes) cubic nitre, and is chiefly used as a ferti- 
lizer and as a source of nitric acid, its tendency to absorb moisture J 
unfitting it for use in gunpowder. In some parts of Europe 
potassium nitrate is made artificially by exposing heaps of animal 
manure, refuse, ashes, and soil to the action of the air and the 
heat of the sun; in the course of a year or two the nitrogen of the 
animal matter becomes oxidixed to nitrates; the latter are removed 
by washing. According to Warington, the nitrifying ferment 
appears capable of existing in three conditions: (1) The nitric fer- 
ment of soil, which convert both ammonium salts and nitrites 
into nitrates; (2) the altered ferment, which converts ammonium 
salts into nitrites, but fails to change nitrites into nitrates ; and 
(3) the surface organism (a bacterium), which changes nitrites into 
nitrates. Similar nitrification 2;oes on in well and river watei-s 



272 THE ACID RADICALS. 

containing nitrogenous organic contaminations such as sewage, 
which thereby tend to become less noxious. 

Note. — Tlie word nitric is from nitre, the English equivalent of 
the Greek v'tTpov {nitron), a name applied to certain natural deposits 
of natron (sodium carbonate) for which potassium nitrate seems at 
first to have been mistaken. Saltpetre is simply sal petrol, salt of 
the rock, in allusion to the natural origin of potassium nitrate. 
Sal pyrunella (from sal, a salt, nn^ pruna, a live coal) is potassium 
nitrate melted over a fire and cast into cakes or bullets. 

The nitric radical is univalent Q^O./). 

Nitric Acid. 

Experiment. — To a fragment of potassium or sodium nitrate 
in a test-tube add a drop or two of sulphuric acid, and warm ; 
vapor of nitric acid, HNO3, is evolved. The fumes may be 
condensed by passing them through a bent delivery-tube into 
a second test-tube which is kept cold. The delivery-tube 
should not be fitted to the first test-tube by means of a cork as 
in the preparation of hydrochloric acid — because the nitric 
acid vapors would strongly act on it — but by means of plaster- 
of-Paris, a paste of w^hich sets hard on being put aside for a 
short time, and is unaflfected by the acid. 

On a somewhat larger scale, nitric acid may be prepared 
by heating, in a stoppered retort, a mixture of equal weights 
of potassium nitrate and sulphuric acid; nitric acid distils over, 
and acid potassium sulphate remains : — 



KNO3 + H^SO, = 


HNO3 


+ KHSO, 


Potassium Sulphuric 


Nitric 


Acid potassium 


nitrate acid 


acid 


sulphate 



The acid potassium sulphate is readily converted into neutral 
sulphate {Fofassi Sulphas, U. S. P.) by dissolving in water, adding 
potassium carbonate until effervesence ceases, filtering, and setting 
aside to crystallize. 

Sodium nitrate, on account of its cheapness, is the nitrate from 
which manufacturers now usually prepare nitric acid. 

Pure nitric acid, HNO3, is colorless liquid of specific gravity 1. 52. 
The most concentrated acid met with in commerce has a specific 
gravity of 1. 5 and contains 93 percent, of real nitric acid ; it fiimes 
disagreeably, is unstable, and, except as an escharotic, is seldom 
used. The U. S. Pharmacopoeia contains three nitric acids : — 
Fuming nitric acid, specific gravity 1.437 ; Acidum Nitricum, 
prepared as above, of secific gravity 1.403 and containing ^S per- 
cent, of real acid ; and Acidnm Nitricum Dilutum, specific gravity 
1.054, containing nearly 10 percent. Either of the more con- 



NITRATES. 273 

centrated acids, although containing water, is usually termed 
''nitric acid." The official nitric acid, of specific gravity 1.403, 
is not a definite hydrous acid although its composition approxi- 
mates to the formula 2HNO3, ^H^O ; it distils at 248.9° F. (120.5° 
C), without change. If a less concentrated acid be heated, it 
loses water ; if a more concentrated acid be heated, it loses nitric 
acid, until the density of 1.403 is reached. Aquafortis is an old 
name for nitric 2LQidi {Aqua fortis simplex, specific gravity 1.22; 
Aquafortis duplex, 1.36). The "concentration" of a specimen of 
nitric acid is determined by volumetric analysis. Nitric anhydride, 
NgOg (sometimes, but erroneously, called anhydrous nitric acid) is 
a soild crystalline substance formed on passing dry chlorine over 
dry silver nitrate. 

Metals reduce nitric acid to the various oxides of nitrogen or 
even to nitrogen itself, according to the concentration of acid, the 
temperature, and the amount of nitrate present. With certain 
metals, such as zinc and iron, and moderately dilute nitric acid, 
some ammonium nitrate is formed. Thus, with zinc, — 

IOHNO3 + 4Zn = 4Zn(N03)2 + NH.NOg + 3H,0 

Aqua Regia. — A mixture of 18 parts of nitric acid (U. S. P.), 
and 82 of hydrochloric acid (U. S. P.), forms the Acidum Nitro- 
hydrochloricum of the Pharmacopoeia. The mixture should be set 
aside for a week in summer or a fortnight in winter, to insure com- 
plete interaction and full development of the chief active product, 
chlorine. 

Acidum Nitrohydrochloricum Dilutum, U. S. P., which is nitro- 
hydrochloric acid diluted with water, may attack organic matter 
with evolution of nitrous gases, hence it should not be dispensed 
with tinctures, etc. , without further dilution. 

A mixture of concentrated nitric and hydrochloric acids is 
known as aqua regia from its property of dissolving gold, the king 
of metals, the action being effected by the chlorine which is liber- 
ated. 

HNO3 + 3HC1 = NOCl + 2Hp + Q\ 
Nitric acid Hydrochloric Nitrosyl Water Chlorine 

acid chloride 

Nitrosyl chloride is an example of the class of compounds known 
as acid chlorides, or acichlorides, formed by the substitution of 
chlorine (CI) for hydroxyl (OH) in an acid ; thus nitrosyl chloride 
may be formed from nitrous acid NO. OH. The substitution of 
CI for OH is often useful in deciding how the oxygen and hydro- 
gen in a substance are combined, for "it is probable that a univalent 
atom like CI can only be substituted for another univalent atom or 
radical, and therefore if it replaces O and H they must be present 
as hydroxyl (-0-H). 

18 



M 



274 THE ACID RADICALS. 

Analytical Reactions of Nitrates, 

1. To a solution of any nitrate (^e.g. KNO3) add sulphuric 
acid and then copper turnings, and warm ; colorless nitric 
oxide, NO, is evolved, which at once unites with the oxygen 
in the tube, giving redfum.es of nitrogen peroxide, NOg. 

2KNO3 + 5H,S0, + 3Cu = 2N0 + 3CuS0, + 4Kfi + 
2KHS0, ; then 2N0 + O, = 2^0^ 

Performed on a larger scale, in a vessel to which a delivery-tube 
is attached, the interaction of nitric acid and copper is the process 
generally adopted for the preparation of nitric oxide. 

Small quantities of nitrates may be overlooked when this test is 
employed, the color of the red fames not being very intense. 

Undiluted nitric acid poured upon copper turnings gives rise to 
the formation of dense red vapors which contain nitrogen perox- 
ide, XO2, nitrous anhydride, '^fis, nitric oxide, NO, and even 
nitrogen, N^, the reaction varying somewhat according to the tem- 
perature of the mixture and (Ack worth) the quantity of cupric 
nitrate in solution. With ordinary copper, dilute nitric acid gives 
nitric oxide, 3Cu + 8HNO3 = 3Cu(N03)2 + 4H2O + 2N0. 

Pure nitric oxide may be obtained by treating mercury with a 
mixture of sulphuric and nitric acids ; or by treating a mixture of 
potassium nitrate 1 part, and ferrous sulphate 4 parts, with sul- 
phuric acid and a small quantity of water. 

2. To a cold solution of a nitrate, even if very dilute, add 
three or four crystals of ferrous sulphate, shake gently for a 
minute in order that some of the sulphate may become dis- 
solved, and then pour some concentrated sulphuric acid down 
the side of the test-tube, so that it may form a layer at the bot- 
tom : a dark-brown or black coloration will appear between 
the acid and the supernatant liquid. 

This is a very delicate test for nitrates. Nitrites give the reac- 
tion without the addition of sulphuric acid. The dark color is due 
to the formation of a compound by the interaction of nitric oxide 
with a portion of the ferrous salt. The nitric oxide is liberated 
from the nitrate by the reducing action of the hydrogen of the sul- 
phuric acid, the sulphuric radical of which is absorbed by another 
portion of the ferrous sulphate, the latter thereby becoming con- 
verted into ferric sulphate. 

2HNO3 + SH^SO, + 6FeS0, = 411^0 + SFe^CSOJa + 2N0 

The process of oxidation is one frequently employed in experi- 
mental chemistry; and nitrates, from their richness in oxygen, and 



NITRATES. 275 

the readiness with which they part with some of it, are the oxi- 
dizing agents often selected for the purpose. In the operation they 
may so decompose as to yield a metallic oxide, nitric oxide, and 
oxygen. Hydrogen nitrate (nitric acid) commonly yields water, 
and the other substances mentioned, as shown by the following 
equation :— 4HNO3 = 2ILfi + 4N0 + SO^. 

When nitrates, other than nitric acid, are used for the purpose 
of oxidation, a strong acid, generally sulphuric, is usually added 
in order that nitric acid may be formed, the latter splitting up 
more readily than most other nitrates. 

The five oxides of nitrogen have now been mentioned, namely : — 



Nitrous oxide (laughing-gas) 


. N^ 


Nitric oxide .... 


. NO 


Nitrous anhydride 


. N,03 


Nitrogen peroxidei 


- . NO, or N2O, 


Nitric anhydride 


. N,0, 



Nitrous oxide is a colorless gas, not altered on exposure to air. 
Nitric oxide is also colorless, but gives red fumes in the air, owing 
to combination with oxygen, NO, being formed. Nitrous anhy- 
dride forms a red vapor condensible to a blue liquid, recent experi- 
ments proving that the red vapor is merely a mixture of nitric 
oxide, NO, and nitrogen peroxide, NO, ; it is only in the liquid 
state (at or below -21° C) that the compound, N^O.^ exists. Nitro- 
gen peroxide is a red vapor condensible to an orange liquid. Nitric 
anhydride is a colorless crystalline solid. The two anhydrides, by 
interaction with water, yield respectively nitrous acid, HNO2, 
(stable at low temperatures but decomposed on heating), and nitric 
acid, HNO3. Nitrous oxide is also probably an anhydride, cor- 
responding to hyponitrous acid, H^NgO,. The silver and sodium 
salts of the latter have the formulse Ag2N202 and Na2N202. 

The compounds of nitrogen and oxygen, formulated above, 
furnish a good illustration of the law of multiple proportions. 

3. Direct the blow-pipe flame against a piece of charcoal 
until a spot is red-hot ; now place on the spot a fragment of a 
nitrate ; deflagration ensues. 

This reaction does not distinguish nitrates from chlorates, but 
indicates the presence of these or other highly oxidized salts, even 
when the quantities are small and other substances are mixed 
with them. 

Gunpowder is an intimate mechanical mixture of 75 parts of 
nitre, 15 to 12J parts of charcoal, and 10 to 12^ parts of suli)hur. 

^ At low temperatures nitrogen peroxide is i*epresented by the formula 
^■204. The molecules of N2O4 decompose, however, on gently warming 
to form 2NO2. 



276 THE ACID RADICALS. 

In order to avoid explosions, the ingredients must be separately 
ground, then moistened with water and mixed to a paste, which 
is afterward granulated and carefully dried. When fired it may- 
be said to yield potassium sulphide, KgS (the white smoke), nitro- 
gen, Xg, carbonic oxide, CO, and carbonic anhydride, CO^, though 
the decomposition is seldom complete. The sudden production of 
a large quantity of highly heated gas from a small quantity of a 
cold solid is sufficient to account for the effects produced by gun- 
powder when fired. 

4. To nitric acid or any other nitrate add a solution of sul- 
phindigotic acid (indigo sulphate); the blue color is discharged. 
Free chlorine also destroys the color of this reagent. 

Indigo Test Solution, U. S. P. — This is the sodium or potassium 
salt of indigotin-disulphonic acid, C^gHg (HS03)2N202, dissolved in 
water, 1 part in 150. 

Antidote. — In cases of poisoning by nitric acid, solution of sodium 
carbonate (common washing soda) or magnesia and water may be 
administered as antidote. 



QUESTIONS AND EXERCISES. 



Trace the origin of nitrates. — In what does cubic nitre differ from pris- 
matic nitre ?— Describe a process by which potassium nitrate may be 
obtained artificially. — State the difference between ordinary nitre and sal 
prunella. — What is the acid radical of the nitrates? — How is tlie official 
nitric acid prepared? — ^Give the properties of nitric acid. — What reactions 
occur when concentrated nitric and hydrocliloric acids are mixed ? — How 
is nitric oxide prepared? — Enumerate and explain the tests for nitrates. 
— What reduction products may be obtained from nitric acid when it is 
employed as an oxidizing agent? — How is nitrous oxide prepared? — 
Enumerate the five oxides of nitrogen. — What is the nature of gunpowder ? 
— What quantity of cubic nitre will be required to produce ten carboys 
of official nitric acid, each containing 114 lbs. ? 



HYPOCHLOROUS ACID, HCIO, AND OTHER HYPO- 
CHLORITIES. 

Experiment. — Place a few grains of red mercuric oxide (or 
better, a small quantity of moist freshly-precipitated yellow 
mercuric oxide) in a test-tube, half fill the tube with chlorine 
water, well shake the mixture, and filter ; the resulting liquid 
is a solution of hypochlorous acid, mercuric oxychloride 
remaiuino; undissolved : — 



'& 



2HgO + 2C1., + H^O = 2HC10 + Hg^OCl^ 



HYPOCHLORITES. 



277 



By the interaction of hyochlorous acid and oxides or hydroxides, 
other pure hypochlorites are formed: — HCIO + NaOH = NaClO 

The action of chlorine on metallic hydroxides gives rise to 
' 'bleaching salts, ' ' which are either mixtures of hypochlorite and 
chloride, or compounds intermediate between hypochlorite and 
chloride (see p. 119, Ciax Chlorinata, U. S. P., also p. 91, Liquor 
Sodce ChlorinatcB, U. S. P.). 



CI. 
2CL 



+ 2NaOH 
+ 2Ca(0H), 



(NaC10,NaCl) 

(CaCip^, CaCl^: 



H,0; 
2H,0. 



The action of strong acids on "bleaching salts" results in the 
evolution of chlorine ; hence the great value of chlorinated lime 
in bleaching operations: — 

(CaCip^, CaClJ + 2H2SO, = 2C\ + 2CaS0, + "Hlfi 

On exposure to air solutions of hypochlorites are slowly decom- 
posed with liberation of hypochlorous acid, recognizable by its 
peculiar odor: — 

2NaC10 + CO, + HP = 2HC10 + Na2C03 

The peculiar odor of this acid, the liberation of chlorine on the 
addition of a strong acid, and their bleaching powers, are the 
characters on which to rely in searching for hypochlorites. 

CHLORIC ACID, HCIO3, AND OTHER CHLORATES. 

Chlorides are formed by boiling aqueous solutions of the bleach- 
ing salts (chlorinated lime, chlorinated soda, chlorinated potash). 
Heat thus converts — 



3(NaC10, NaCl) ~ 
Chlorinated soda 


>■ into 


1 
1 


NaC103 

Sodium 
chlorate 


3(KC10, KCl) ] 
Chlorinated ' 
potash 


into 


1 
1 


KCIO3 

Potassium 
chlorate 


8[Ca(C10)2, CaClJ " 

Chlorinated 
lime 


> into 


1 


CaCClO^) 

Calcium 
chlorate 



and 



and 



and 



SNaCl 

Sodium 
chloride 

5KC1 

Potassium 
chloride 

5CaCl, 
Calcium 
coloride 



Potassium Chlorate. 



Potassium Chlorate {Pofassil Chloras, U. S. P.), is commerci- 
ally made by saturating with chlorine gas a moistened mixture of 
3 parts of potassium chloride and 10 of calcium hydroxide, and 



wmm 



278 THE ACID RADICALS. 

well boiling the product. Chlorinated lime is first formed ; this, 
on continued boiling with water, splits up into calcium chloride 
and calcium chlorate; and the latter interacting with the potas- 
sium chloride yields calcium chloride and potassium chlorate. 

6Ca(OH)2 + 6CI2 ■= 3[CaCl2, Ca(C10)J + eH^O; 

3[CaCl2, Ca(C10)J =^Q2i{C\0.^\ + SCaCl^; 

CalClOg)^ + 2KC1 = CaCl^ + 2KCIO3 

The operation may be conducted on a small scale by rubbing the 
ingredients together in a mortar in the foregoing proportions, add- 
ing enough water to make the whole assume the character of damp 
lumps, placing the porous mass in a funnel (loosely plugged with 
fragments of glass) and passing chlorine up through the mass by 
attaching to the neck of the funnel the tube delivering the gas. 
When the whole mass has become of a slight pink tint (due to a 
trace of permanganate from manganese present as impurity in the 
calcium hydroxide) it should be turned into a dish, well boiled 
with water, filtered, the filtrate evaporated if necessary, and set 
aside; the potassium chlorate separates in tabular monoclinic 
crystals, calcium chloride remaining in the mother-liquor. In 
this process potassium carbonate may be used in the place of potas- 
sium chloride. 

6CI2 + K2CO3 + 6Ca(OH)2 = 

Chlorine Potassium carbonate Calcium hj^droxide 

2KCIO3 + CaCOs 4- 5CaCl, + 6H,0 

Potassium Calcium Calcium Water 

chlorate carbonate chloride 

Potassium chlorate is now prepared on the commercial scale by 
the electrolysis of a solution of potassium chloride. 

Potassium chlorate is soluble is water to the extent of 6 or 7 
parts in 100 at ordinary temperatures. It is usually administered 
medicinally in aqueous solution, sometimes also in lozenges (y/'o- 
chisci Potassii Chloratis, U.S. P.). Potassium chlorate must on 
no account be rubbed with sulphur or sulphides, in a mortar or 
otherwise, friction of such mixtures often given rise to violent 
explosions. 

Potassium chlorate when heated to a temperature not greatly 
beyond its fusing point, yields potassium chloride and oxygen, 
and is the salt commonly employed in the preparation of this gas 
for experimental purposes. If the action be carried on at as low 
a temperature as possible, and be arrested when one hundred parts 
of the chlorate have yielded 7. 84 parts of oxygen, the residue will 
be found to contain onlv potassium perchlorate, KCIO^, and chlo- 
ride; IOKCIO3 = 6KClb, + 4KC1 + 3O2 (Tead). A higher tem- 
perature causes the decomposition of the perchlorate; KCIO^ = 



CHLORATES. 279 

KCl H- 2O2. When the chlorate is heated with manganese per- 
oxide, no perchlorate is formed. 

Sodium Chlorate [Sodii Chloras, U.S. P.), NaClOg, is prepared in 
the same way as potassium chlorate. 

Chloric acid, HCIO3, may be isolated by decomposing barium 
chlorate with dilute sulphuric acid, but is unstable, quickly decom- 
posing into chlorine, oxygen, and perchloric acid. 

Analytical Reactions of Chlorates. 

1. To a solution of a chlorate add solution of silver nitrate ; 
no precipitate is produced, showing that silver chlorate is solu- 
ble in water. Evaporate another portion of the solution to 
dryness, and place the residue in a small dry test-tube (or 
simply drop a fragment of a chlorate into a test-tube) and 
heat strongly ; oxygen is evolved, and may be recognized by 
its power of rekindling an incandescent match inserted in the 
tube. Boil the residue with water, and again add solution of 
silver nitrate ; a white precipitate is produced which possesses 
all the characters of silver chloride, as described under hydro- 
chloric acid. 

2. To a small fragment of a chlorate add two or three drops 
of concentrated sulphuric acid ; an explosive gas, chlorine 
peroxide, ClO^, is evolved, which somewhat resembles chlorine 
in odor, but possesses a deeper color. 

3KCIO3 + 2H,S0, = 2C10, + KCIO, + 2KHS0, + H^. 

Warm the upper part of the test-tube to 150° or 200° F. 
(65.5° to 93.3° C), or introduce a hot wire ; a sharp explosion 
ensues, due to decomposition of the chlorine peroxide into 
chlorine and oxygen. 

3. Heat a small fragment of a chlorate with hydrochloric 
acid; a yellowish green gaseous mixture called euchlorine is 
evolved. Its color is deeper than that of chlorine, hence the 
name (from so, eu, well, and xXmpdc, chloros, green). It is 
really a mixture of that element with chlorine peroxide. 

4. Direct the blowpipe-flame against a piece of charcoal 
until a spot is red-hot, and then place on the spot a fragment 
of a chlorate ; deflagration ensues, as in the case of nitrates. 

Perchloric acid, HCIO^. — Crude potassium perchlorate obtained 
as already described, is boiled (in a fume-cupboard) with hydro- 
chloric acid to decompose any chlorate that may be present, and 
then separated from chloride by washing and crystallization, chlo- 



280 THE ACID RADICALS. 

ride being far more soluble in water than percblorate. Perchloric 
acid is then obtained by distilling the potassium perchlorate with 
sulphuric acid; it is stable, and is occasionally administered in 
medicine. 

Table of the Chlorine Acids. 

Hydrochloric acid . . . HCl 

Hypochlorous acid . . . HCIO 

Chloric acid HCIO3 

Perchloric acid . . ... HCIO, 



The acid radicals of the above chlorine acids are univalent, as 
indicated in the various formulae. 

Bromates. 

Bromates are salts closely resembling chlorates and iodates. The 
formula of bromic acid is HBrOg. The presence of bromates, as 
impurity, in bromides is shown by the production of a yellow color, 
due to the liberation of bromine, on the addition of dilute sulphuric 
acid. 

5KBr -f KBrOg -f BKH^SO, = 6KHS0, + 3H2O + 3Br2 

Iodates. 

Iodic Acid, HIO3. — Iodine is warmed in a flask with five times 
its weight of fuming nitric acid (sp. gr. 1,437), in a fume-cupboard, 
until all action ceases. On cooling, iodic acid separates in small 
pyramidal crystals. These are separated, the residual liquid eva- 
porated to dryness to remove excess of nitric acid, the residue and 
the first crop of crystals dissolved in a small quantity of boiling 
water, and the solution set aside to crystallize. Neutralized with 
carbonates or hydroxides, it yields iodates. 

Potassium iodate and sulphurous acid mutually interact with 
elimination of iodine (and formation of a blue color, if starch be 
present). Sulphurous acid occurring as an impurity in acetic and 
other acids may thus be detected. 

2KIO3 + 5H2SO3 = I2 + SH^SO, + 2KHS0, + H,0 

Ferric iodate, or rather Oxyiodate, Fe20(I03)^, 8H2O, is precipi- 
tated on adding a solution of ferric chloride to solution of potassium 
iodate. When heated with sulphuric acid and potassium bichro- 
mate, most iodides are decomposed, yielding iodine and a sulphate 
of the metal ; silver iodide, however, is an exception, as, though it 
gradually dissolves, no iodine is separated, and on diluting the 
solution and allowing it to cool, a yellow precipitate consisting of 
impure silver iodate is deposited. 



ACETATES. 281 

QUESTIONS AND EXERCISES. 

How may hypochlorous acid be formed ? — By what reaction is chlorine 
eliminated* from hypochlorites? — State the general i-eaction by which 
chlorates are formed. — Give details of the preparation of potassium chlor- 
ate. — Mention the properties of potassium chlorate. — What decompositions 
occur when potassium chlorate is heated ? — Find the formula weight of 
potassium chlorate.- -Wha. "^'eight of oxygen is produced when 1 oz, of 
potassium chlorate is complettly decomposed, and how much potassium 
chloride remains? — One hundred cubic inches of oxygen, at 60° F. and 
barometer at 30 inclies, weighing 34.203 grains, and one gallon containing 
277i cubic inches, what weight of potassium chlorate will be i-equired to 
yield 10 gallons of the gas ? — Ans. 5^ oz. — Calculate the weight of potas- 
sium chloride obtainable from 100 parts of potassium chlorate. — How may 
the presence of chlorides in chlorates be demonstrated ? — Mention the 
tests for chlorates. — Give the formula of chlorine peroxide. — What is 
euchlorine ? — How is perchloric acid prepared ? — Enumerate the chlorine 
acids. — How may iodic acid be made ? 



ACETIC ACID, HC^Efi^, AND OTHER ACETATES. 

Source. — Acetic acid is said to occur naturally in small quantity 
in certain plant-juices and animal fluids, but is usually an artificial 
product. Much acetic acid is produced during the destructive dis- 
tillation of wood. When first discovered in this operation the 
acid was regarded as a new one, and was named pyroligneous acid, 
a hybrid word from nvp, pur, fire, and lignum, wood, a term still 
retained for the crude acid. The latter, neutralized by calcium 
carbonate, the solution evaporated to dryness, and the residue gently 
heated to drive off volatile tarry matters, yields calcium acetate. 
Acetate acid is obtained in a state of purity (mixed with water only) 
by starting from this crude calcium acetate, converting it into 
sodium acetate, recrystallizing the latter and distilling it with 
dilute sulphuric acid. Diluted acetate acid is sometimes sold as 
white vinegar, one of the many varities oi vinegar. It has been known 
as wood vinegar for the past sixty or seventy years. It is generally 
colored brown with caramel to meet the taste of the public. In 
Germany and France large quantities of acetic acid are made by 
the oxidation of the alcohol in inferior wines, in the presence of a 
bacterium called Mycoderma Acefi (the Bacterium Mycodermi of 
Cohn) ; hence the white-wine and red-wine vinegars (^vinegar, from 
the French vi?i, wine, and aigre, sour). This bacterium may be 
cultivated, and the manufocture of vinegar from alcohol and water 
is carried out by its aid on the large scale. In England also the 
domestic form of acetic acid (brown vinegar) commonly has an alco- 
holic origin : infusion of malt and unmalted grain, or sometimes 
the latter alone after treatment with sulphuric acid, is fermented ; 
and the resulting alteration of its sugar, instead of being arrested 
when the product is an alcoholic liquid, a sort of beer, is allowed 



282 THE ACW RADICALS. 

to go on to the next stage, acetic acid ; it usually contains from 3 
to 6 percent, of actual acetic acid or hydrogen acetate, HC.^H O^. 
Different strengths of vinegar are sold under the numbers 16, 18, 
20, 22, 24, corresponding to the number of grains of anhydrous 
sodium carbonate neutralized by one imperial fluid ounce of the 
vinegar, or, broadly, to 4, 4^, 5, 5^ and 6 percent, of acetic acid 
respectively. All of these ''brewed vinegars" are further colored 
with caramel, to suit the popular taste. Vinegar is a generic term 
applicable to any one or all varieties. Its essential component is 
acetic acid. 

Vinegar of Squill (Acetum Scillce, U. S. P.), and Vinegar of 
Opium {Acetum Opii, U. S. P.), or "black drop," contain dilute 
acetic acid, that is, wood vinegar. 
^The^acetic radicalj JO3H3.O4, is. umyalent.N 

Acetic acid is regarded as containing the*Tadical acetyl (C2H3O) 
united with hydroxyl (OH), and the acetates as containing metal in 
place of the hydrogen of the hydroxyl group. By interaction with 
phosphorus trichloride, acetic acid yields acetyl chloride, CgHgOCl. 
Acetyl chloride and sodium acetate interact to give sodium chloride 
and acetic anhydride. 



C2H3O I CI i 



C2H3OO i Na 



{Q^nfiyp + NaCl 



By interaction with water, acetic anhydride yields acetic acid : 

Note on Anhydrides. —V^ to this point an anhydride has been 
regarded as a substance derived from an acid by removal of the 
whole hydrogen of the acid, together with as much of its oxygen 
as with the hydrogen forms water. This does not apply to acetic 
anhydride, and must therefore be somewhat qualified. An anhy- 
dride is derived from an acid, the acid having lost the whole of its 
replaceable hydrogen, and as much oxygen as is necessary to form 
water with that hydrogen. 

The relation of acetic acid to alcohol will be evident from the 
following equation representing the formation of the acid : — 

C,H,0 + 0^ = C^H.O, + H.,0 
Alcohol Acetic acid 

Acetates in aqueous solution are liable to decomposition. In solu- 
tion of morphine acetate a fiingoid growth occasionally forms, ace- 
tic acid disappears, and morphine is deposited. Solution of ammo- 
nium acetate is liable to a similar change, gradually becoming alka- 
line. 



faC^HgO^ 


+ H,SO, = 


Sodium 


Sulphuric 


acetate 


acid 



ACETATES. 283 

Experiment. — To a few grains of sodium acetate in a test- 
tube, add dilute sulphuric acid, and heat ; acetic acid is evolved, 
and may be condensed by passing it through a bent tube i 

adapted to the test-tube by means of a cork in the usual way. |' | 

HC2H3O, + NaHSO, 
Acetic acid Acid sodium 

sulphate 

The above is the process by which acetic acid is obtained from 
sodium or calcium acetate on the large scale. As in the cases of || 

nitric and hydrochloric acids, the term ''acetic acid" is usually - ' 

applied to the aqueous solution of the acid. Acidum Aceticum, 
U. S. P. , contains not less than 36 percent, of hydrogen acetate, 
HC2H3O2. Acidimi Aceticum Dilutu7n, JJ . S. P., contains not less 
than 6 percent. Glacial acetic acid, HCgHgO.^, contains no water. 
It solidifies to a crystalline mass at temperatures below 63° F. (17. 2° 
C), hence the appellation glacial (from glades, ice). Good com- 
mercial glacial acetate acid {Acidum Aceticum Glaciale, U. S. P.), 
does not contain more than 1 percent, of water ; it solidifies when 
cooled, and again liquefies at about 59° F. (15° C.) ; its specific 
gravity is 1.049. Although water is specifically lighter than this 
acetic acid, yet the addition of water at first raises the sp. gr. of 
the acid ; evidently, therefore, contraction takes place on mixing 
the liquids : after 10 percent, has been added, the addition of more 
water produces the usual effect of dilution of a liquid with one 
specifically lighter — namely, lowering of the specific gravity. 
Glacial acetic acid mixes readily with most oils. 

Analytical Reactions of Acetates. 

1. To an acetate add sulphuric acid, and heat the mixture ; 
the characteristic odor of acetic acid is evolved. 

Note. — Iodine, sulphurous anhydride, and other substances 
which possess a powerful odor, may mask that of acetic acid. 

2. Repeat the above reaction, a few drops of alcohol being 
first added to the acetate ; acetic ether (ethyl acetate, 
C2H5C2H3O2), possessing a characteristic pleasant odor, is 
evolved. 

3. Heat a fragjnent of a dry acetate (potassium, sodium, 
calcium or barium acetate, for example) in a test-tube, and 
notice the odor of the gaseous products of the decomposition ; 
among them is acetone, CgH^O, the odor of which is char- 
acteristic. Blackening takes place in most eases. A carbon- 
ate remains in the test-tube. {See tests for carbonates.) 



284 THE ACID RADICALS. 

4. To a solution of an acetate, made neutral by the addition 
of acid or alkali, as the case may be, add a few drops of neu- 
tral solution of ferric chloride ; a deep-red liquid results, owing 
to the formation of ferric acetate, Fe(C2H,02)3. Boil ; a red 
precipitate of ferric oxyacetate is formed, leaving the liquid 
colorless. 

Analytical Note. — The student should observe that all normal 
acetates are soluble in water. Silver acetate, AgCjHgO.^, and mer- 
curous acetate, HgC2H302, are only sparingly soluble in cold water, 
but the fact can seldom be utilized in analysis. Hence, precipi- 
tation not being available, peculiarities of color and odor, the next 
best characters on which to rely, are usually adopted as means by 
which acetates may be detected. Most acetates, like many other 
organic compounds, char when heated to a high temperature. 



QUESTIONS AND EXERCISES. 



What is the formula of acetic acid ? — State the relation of acetic acid to 
other acetates. — What is the molecular weight of acetic acid ? — Name the 
sources of acetic acid.— What is pyroligneous acid ? — From what compound 
is the acetic acid of most varieties of vinegar derived ? — What is the nature 
of the " Vinegars " of Pharmacy ? — How may acetic acid be obtained from 
sodium acetate? — How much hydrogen acetate is contained in each of the 
official acetic acids ? — Enumerate the tests for acetates. 



HYDROSULPHURIC ACID, H^S, AND OTHER 
SULPHIDES. 

Occurrence and varieties of Sulphur.— The acid radical of hydro- 
gen sulphide, hydrosulphuric acid, sulphydric acid, or sulphuretted 
hydrogen and other sulphides, is sulphur, S. Sulphur occurs free 
in nature, and also in combination with metals, as already stated 
in describing the ores of some of the metals. It also occurs in 
coal, chiefly as iron pyrites, and sulphur compounds are obtained, 
as waste-products, in' the manufacture of coal-gas. Most of the 
sulphur used in medicine is imported from Sicily, where it occurs 
chiefly associated with blue clay. It is purified by fusion, subli- 
mation, or distillation. Melted and poured into moulds, it forms 
roll sulphur. It is slightly volatile, even on a water-bath. If dis- 
tilled, and the vapor carried into large chambers, so that it may 
be condensed rapidly, it forms crystals which are so minute as to 
give the sulphur a pulverulent character; this is sublimed sulphur 
[Sulphur Sublimatum, U. S. P.), or flowers of sulphur. Sulphur, 
washed with dilute ammonia to remove traces of sulphuric acid 
(often 0.1 percent., resulting from very slow oxidation of sulphur 



SULPHIDES. 285 

in ordinary moist air), or, possibly, arsenous sulphide, constitutes 
washed sulphur [Sulphur Lotum, U. S. P.). The third common 
form, precipitated sulphur {Sulphur Proicipitatum, U. S. P.), will 
be noticed subsequently. Sulphur also occurs in nature in com- 
bination as a constituent of animal and vegetable tissues, as sul- 
phurous anhydride, SO.^, in volcanic vapors, and as hydrogen sul- 
phide in some mineral waters. Sulphur exists in several allo- 
tropic forms, of which the following four may be noticed : — 1. 
Octahedral sulphur — the native and most stable form. 2. Pris- 
matic sulphur, obtained by melting the octahedral variety, and 
cooling until a crust forms. 3. Plastic sulphur, obtained by 
heating melted sulphur to a temperature of (440° C.) 836° F., and 
pouring into cold water. 4. Amorphous sulphur, obtained in the ., 

proportion of 5-6 percent, when the octahedral variety is sublimed. { 

Allotropy. — The existence of more than one variety of the same i 

elementary substance (as instanced in the varieties of sulphur |( 

enumerated above) illustrates what is known in chemistry as allo- 
tropy [akloq, alios, another; Tpoirog, tropos, condition). Other 
instances are met with in the different forms of carbon, phosphorus, 
etc. 

Black sulphur or Sulphur vivum nigrum is the misleading name 
of a grayish mixture of sulphur with a great variety of impurities, 
generally including arsenic. The article should not be used for 
any medicinal purpose. 

Quantivalence. — Sulphur behaves as a sexivalent element in sul- 
phuric anhydride, SOg, a substance which will be noticed under 
sulphuric acid, and as quadrivalent in sulphurous anhydride, S.Og, 
while it is frequently bivalent, as in hydrogen sulphide, H^S. 

Molecular Formula. — At temperatures between the boiling point 
of sulphur (448.4° C.) and about 1000° C, the vapor density of 
sulphur gradually diminishes as the temperature raises. Above 
1000° C, or so, it is constant and then corresponds to the mole- 
cular formula Sj. 

Precipitated Sulphur. 

Experiment 1. — Fre^SLre Precipitated Sulphur (Sulphur Proe- 
cipitatum U. S. P.), or Milk of Sulphur, by boiling a few grains 
of flowers of sulphur (2 parts) with calcium hydroxide (1 part) 
and water in the test-tube (larger quantities in an evaporating- 
basin), filtering, and (reserving a small portion of the filtrate) 
adding dilute hydrochloric acid until the well-stirred milky 
liquid still has a faintly alkaline reaction to test-paper ; sul- 
phur is precipitated, and may be collected on a filter, washed, 
and dried (at about 130° F., 54.4° C). Excess of acid must 
be avoided in order to prevent contamination of the precipi- 



286 THE ACID RADICALS. 

tate with traces of arsenous sulphide (from the decomposition 
of any thiarseuite, produced from arsenous sulphide present as 
impurity in the sulphur employed). 

This is the method of the Pharmacopoeia. — Calcium poly- 
sulphide and thiosulphate are first formed: — 

3Ca(0H), + 6S, = 2CaS5 + C2.^fi^ + 3H,0 

Calcium Sulphur Calcium Calcium Water 

hydroxide polysulphide thiosulphate 

On adding the acid, both salts are decomposed and (partly in 
consequence of an intermediate reaction) sulphur separates : — 

2CaS. + CaS,03 + 6HC1 = 3CaCl, + SH^ -f- 6S, 

Calcium Calcium Hydrochloric Calcium Water Sulphur 

polysulphide thiosulphate acid chloride 

The calcium polysulphide yields hydrogen sulphide and milk- 
white sulphur on the addition of the acid. The calcium thiosul- 
phate then yields sulphurous anhydride as well as yellowish sul- 
phur. The gases interact and give sulphur and water, \qy\ little 
hydrogen sulphide escaping : this is the intermediate reaction just 
alluded to. A little pentathionic acid (p. 296) is also said to be 
formed. 

4H2S + 2SO2 = 3S, + AlAfi 

Experiment 2. — Calcareous Precipitated Sulphur. T\\q old 
"jNIilk of Sulphur." — To a sulphur solution prepared as before 
(or to the reserved portion) add a little dilute sulphuric acid ; 
the precipitate is in this case largely mixed with calcium sul- 
phate: — 

2CaS. + CaSPs + SH^SO, + 3H,0 = 3(CaSO,,2H20) + 68^ 

Calcium Calcium Sulphuric Water Calcium sulphate Sulphur 
polysulphide thiosulphate acid 

Place a little of each of these specimens of "precipitated sul- 
phur," with a drop of the supernatant liquid, on a strip of 
glass, place a cover-glass upon each, and examine the precipi- 
tates under a microscope ; the pure sulphur will be found to 
consist of minute grains or globules, the calcareous precipitate 
to contain comparatively large crystals (hydrous calcium sul- 
phate). 

Note. — Some of the precipitated sulphur met with in trade in 
England, is still thus mixed with calcium sulphate, most of such 
specimens containing two-thirds of their weight of the latter sub- 
stance. Formerly, purchasers were so accustomed to the satiny 
appearance of the mixed article as to regard real sulphur with sus- 
picion, sometimes refusing to purchase it. The mixed article is, 
certainly, somewhat more easily miscible with aqueous liquids. 



SULPHIDES. 



287 



The calcareous precipitated sulphur yields a white ash (anhy- 
drous calcium sulphate) when a little is burnt off on the end of a 
table-knife or sj^atula or in a porcelain crucible. To ascertain, 
exactly, the amount of the sulphate, place a weighed quantity in a 
tarred porcelain crucible, and heat until no more vapors are evolved. 
The weight of the residual anhydrous calcium sulphate (CaSO^ = 
135.15), multiplied by 1.264, is the amount of hydrous calcium 
sulphate (CaSO^, 2H2O = 170.9) present in the original quantity 
of calcareous sulphur. 

Hydrogen Sulphide, Hydrosulphuric Acid, or Sulphuretted Hydro- 
gen. — The preparation of hydrogen sulphide was described on p. 
100. 

Hydrosulphides. — Besides ammonium hydrosulphide, which has 
already been referred to on p. 100, solutions of sulphides and of 
other hydrosulphides may be obtained by the interaction of hydro- 
gen sulphide with solutions of hydroxides. Sodium and potassium 
sulphides and hydrosulphides, Na2S and K^S, and NaSH and KSH, 
are the most important of these substances : 

2K0H + H^S - K^S + 2H2O 
NaOH + H^S = NaSH + H^O. 

Like ammonium hydrosulphide, they act as solvents for the arsenic, 
antimony, and stannic sulphides, forming with them thio- salts. 
They all dissolve sulphur, producing yellow solutions. 



Analytical Reactions of Sulphides and Hydrosulphides. 

To a sulphide or hydrosulphide add a few drops of hydro- 
chloric acid ; hydrogen sulphide will probably be evolved, 
recognizable by its odor. If the sulphide is not acted upon 
by the acid, or if free sulphur be under examination, mix a 
minute portion with a fragment of solid sodium hydroxide, 
and fuse in a silver capsule (or old spoon). When cold, 
place a drop of dilute hydrochloric acid on the fused mass ; 
hydrogen sulphide is evolved, and a black stain due to silver 
sulphide, AggS, is left on the silver. 

The most convenient reagent for detecting sulphide in ammonia 
water is cupric ammonium sulphate, which gives a black precipi- 
tate of cupric sulphide if a sulphide be present. 

Sulphur Iodide, S.J2 (Sulphuris lodidum, U. S. P.), has already 
been mentioned under Iodine. A chloride, ^.fi\, and bromide, 
S2Br2, may also be formed from the elements, A mixture of sul- 
phur and sulphur chloride is sometimes met with under the name 
of sulphur hypochloride, 



288 THE ACID RADICALS. 

QUESTIONS AND EXERCISES. 

In what forms does sulphur occur in nature? — State the modes of 
preparation of the three chief commercial varieties of sulphur. — In what 
respect does the atom of sulphur vary in quantivalence ? — Describe the 
preparation of hydrogen sulphide. — What are the characters of pure 
precipitated sulphur ? — Give equations explanatory of the reactions which 
occur in preparing precipitated sulphur? — Describe the microscopic test 
for calcareous precipitated sulphur. — Mention a method of detecting cal- 
cium sulphate in precipitated sulphur. — Mention the tests for sulphides, 
and the character by which hydrogen sulphide is distinguished from 
other sulphides. — How are sulphides insoluble in acids tested for sulphur? 
— How would you detect a trace of sulphide in ammonia solutions ? 



SULPHUROUS ACID [H,,S03], AND OTHER SULPHITES. 

When sulphur is burnt in the air, it combines with oxygen and 
forms sulphurous anhydride, SO^, occasionally, but erroneously, 
called sulphurous acid. It is a pungent, colorless gas, readily 
liquefied on being passed through a tube cooled by & freezing-mix- 
ture composed of two parts of well-powdered ice (or of snow) with 
one part of common salt. If sulphurous anhydride is passed into 
water, heat is evolved and some sulphurous acid [H^SOg], is 
apparently formed in solution. 

Hydrous sulphurous acid may be obtained in crystals by freez- 
ing a concentrated aqueous solution, but it is very unstable. 

Quantwalence. — The acid radical of the sulphites is bivalent 
(SOg^^. Acid sulphides, such as acid potassium sulphite, KHSO3, 
and normal sulphites, such as sodium sulphite, Na.^SOg, are known. 

Note. — The sulphites are so named in accordance with the usual 
rule that salts corresponding with acids whose names end in ous 
have a name ending in ite. 

Experiment. — To a few drops of sulphuric acid in a test- 
tube add a piece of charcoal and apply heat ; sulphurous anhy- 
dride (mixed w^ith carbonic anhydride) is evolved, and may 
be conveyed through a bent tube into a small quantity of cold 
water in another test-tube. Larger quantities of the gas may 
be made in a flask. The product is Acidum Sulphurosum, 
U. S. P.). It contains not less than 6 percent, of sulphurous 
anhydride. 



2H,S0, 


+ c - 


= CO., + 


2H,0 


+ 2S0., 


Sulphuric 


Carbon 


Carbonic 


Water 


Sulphurous 


acid 




anhydride 




anhydride 



Sulphurous anhydride may also be made by heating copper, 
mercury, or iron Avith concentrated sulphuric acid, a metallic sul- 
phate being formed. Also by heating sulphur with sulphuric 
acid. 



SULPHITES. 289 

Sulphides are generally made by passing sulphurous anhydride 
into solutions of hydroxides or carbonates, or into water containing 
such substances in suspension. In the case of carbonates, carbonic 
anhydride escapes. The formula of Sodium Sulphite {Sodii Sul- 
phis, U. S. P.), is NagSOg, THgO ; it occurs in colorless efflores- 
cent prisms, soluble in water or alcohol. As "antichlor" it was 
formerly used for removing traces of chlorine from paper pulp 
(sodium thiosulphate is now employed). The formula of Sodium 
Bisulphite {Sodii Bisuiphis, U. S. P.), is NaHSOg. The so-called 
Bisulphite of Lime, used by brewers for retarding or arresting 
fermentation and oxidation, and employed for various antiseptic 
purposes, is made by passing sulphurous anhydride, SO2, into thin 
milk of lime. Its specific gravity varies from 1.050 to 1.070, and 
it corresponds to from 4 to 6 percent, of sulphurous anhydride. 
The so-called meta-bisulphides of potassium and sodium, used in 
photography, are really anhydrosulphites, KgSgOg and NagSgO^. 
They may be obtained by passing sulphurous anhydride into hot 
saturated solutions of potassium and sodium carbonates, respec- 
tively. Sulphurous anhydride is very soluble in alcohol. 

Analytical Reactions of Sulphites, 

1. To a sulphite (sodium sulphite, for instance, — made by 
passing sulphurous anhydride into solution of sodium carbon- 
ate) add a drop or two of dilute hydrochloric acid ; a pecu- 
liarly pungent odor is produced (sulphurous acid). 

This odor is the same as that evolved on burning sulphur. It is 
due, probably not to sulphurous anhydride, SOg, but to sulphur- 
ous acid, H2SO3, formed by the union of the sulphurous anhydride 
with either the moisture of the air or that on the surface of the 
mucous membrane of the nose. The gas is highly suffocating. 

2. To a sulphite add a little water, a fragment or two of 
zinc, and then hydrochloric acid ; hydrogen sulphide is evolved, 
recognizable by its odor and by its action on a piece of paper 
placed like a cap on the mouth of the test-tube and moistened 
with a drop of solution of lead acetate (a black stain of lead 
sulphide being formed). The presence of sulphurous acid in 
acetic acid or in hydrochloric acid may be detected by means 
of this test :- H^SO^ + 6H =.. H,S + SH^. 

Other Reactions. 

To separate portions of a solution of a normal sulphite add 
barium nitrate or chloride, calcium chloride, and silver nitrate ; 
19 



290 THE ACID RADICALS. 

in each case a white precipitate of a metallic sulphite results. 
The barium sulphite is soluble in dilute hydrochloric acid ; 
but if a drop or two of chlorine water is first added, barium 
sulphate is formed, which is insoluble. The other precipitates 
are also soluble in dilute acids. Silver sulphite is decomposed 
on boiling, sulphuric acid being formed, and metallic silver 
set free, the precipitate darkening in color. 

To recognize the three radicals in an aqueous solution of sul- 
phides, sulphites, and sulphates, add barium chloride, filter, and 
wash the precipitate. In the filtrate, sulphides are detected by 
the evolution of hydrogen sulphide on the addition of an acid. 
In the precipitate, sulphites are detected by observing the odor 
of sulphurous acid produced on adding hydrochloric acid, and sul- 
phates are detected by the insolubility of barium sulphate in the 
acid. 



QUESTIONS AND EXERCISES. 

What are the differences between sulphurous acid and sulphurous anhy- 
dride, sulphites and acid sulphites ? — State the characters of sulphurous 
anhydride. — How is the official sulphurous acid prepared ? — By what tests 
may sulphurous acid be recognized in acetic acid ? — Give a method by 
which sulphites may be detected in presence of sulphides and sulphates. 



SULPHURIC ACID, H^SO^, AND OTHER SULPHATES. 

Many sulphates occur in nature. The most important of these 
3iVQ heavy spar, barium sulphate, BaSO^; gi/psinn, calcium sulphate, 
CaSO^,2H20; and Epsom salt, magnesium sulphate, MgSO^, THgO. 

Preparation of Sulphuric Acid. — Sulphur itself, or more usually 
the sulphur in iron pyrites, is first converted into sulphurous 
anhydride by burning in air, and this gas, by oxidation in presence 
of moisture, is then converted into sulphuric acid: SO2-I-H2OH-O 
= H^SO^. The oxygen necessary to oxidize the sulphurous 
anhydride may be obtained directly from the atmosphere, but the 
process is a very slow one. The transference of oxygen to the 
sulphurous anhydride, in presence of moisture, to the form sul- 
phuric acid, is greatly hastened in practice by the use of nitric 
oxide. This gas, when mixed with air, takes up oxygen to form 
nitrogen peroxide, XOg which, in turn, is easily reduced again to 
nitric oxide by parting with half its oxygen to the moist sulphur- 
ous anhydride. The nitric oxide so liberated reunites with oxy- 
gen, again forming nitrogen peroxide which again undergoes 
similar reduction to nitric oxide, so that the process becomes 



SULPHATES. 



291 



virtually a continuous one, a small proportion of nitric oxide 
sufficing to convert relatively large quantities of sulphurous anhy- 
dride, oxygen, and water into sulphuric acid. 

The nitric oxide is in the first instance obtained from nitric 
acid, and this from sodium nitrate by the action of a small quan- 
tity of sulphuric acid. 

The following equations represent the chief steps: — 



NaNOg + H^SO, = NaHSO, + HNO3, 



fi + 3S02 + 2HN03 


= SH^SO, 


2N0 + O2 - 


2N0„ 


H,0 + SO, + NO, = 


= H^SO, + 



2N0, 



NO 

Quantivalence. — The sulphuric radical is bivalent (SO/0> and 
acid as well as normal sulphates are known. Acid potassium 
sulphate KHSO,, is an illustration of the former, sodium sul- 



phate, 



Na^SO,, of the latter. 



Manufacture of Sulphuric Acid, 

Chamber Process. — On the large scale, sulphurous anhydride 
together with nitric acid vapor is carried by means of flues into 
large leaden chambers, where jets of steam supply the necessary 
moisture, ^ and into which air is also passed. The resulting dilute 
sulphuric acid, which collects on the floor of the chambers, is 
drawn off", and is concentrated by evaporation in leaden, and 
finally in glass or platinum, vessels. 

Contact Process. — Sulphuric acid is now made in some places 
on the manufacturing scale by aid of the recently perfected ' 'con- 
tact" process. In this process sulphurous anhydride, SO2, com- 
bines directly with oxygen to form sulphuric anhydride, SO3, 
when mixed with oxygen and passed through tubes in which the 
mixture is exposed to a large surface of finely divided metallic 
platinum in the form of plantinized asbestos. The sulphurous 
anhydride is obtained by roasting iron pyrities and must be puri- 
fied in a most thorough manner from the last traces of volatile 
arsenic compounds and from some other volatile compounds present 
as impurities derived from the pyrites; but it remains mixed with 



1 In the absence of a sufficient supply of water vapor, a white crystalline 
substance, uitro-sulphojiic acid, SOo<jJq , may be produced (sometimes called 
"chamber crystals"). The manufacturer of sulphuric acid takes steps to 
ensure the presence of so much water vapor that these crystals are never 
formed. The following equations represent the formation of nitro-sulphonic 
acid and its decompostion by Avater :— 



2SO2 



+ 3N0o + HoO 
NO2 + H.,0 = 



HO 

NOo 



2SOo<,Mr»., + NO 
2H2SO4 + NO2 + NO 



292 THE ACID RADICALS. 

considerable quantities of oxygen and nitrogen from the air drawn 
into tlie furnaces in which the pyrites are roasted. The cooled 
mixture of gases is then brought as thoroughly as possible into 
contact with platinized asbsetos placed in trays in upright iron 
pipes. To begin with, these pipes are heated in order to start the 
combination; but they are afterward exposed to the cooling 
influence of the external air, the heat given out by the occurrence 
of the reaction being more than sufficient to maintain the tempera- 
ture at the i^oint at which the maximum yield of sulphuric anhy- 
dride is obtained. 

The sulphuric anhydride produced by the reaction is i^assed 
into previously prepared 98 percent, sulphuric acid in which it is 
rapidly absorbed with formation of pyrosulphuric acid, H2S20^; 
and the latter is then mixed with the quantity of water necessary 
to reduce it again to the conditon of 98 percent, sulphuric acid or 
to sulphuric acid of any required concentration: — 

H^Sp, + H^O = 2H2SO, 

Ferric oxide may be used as the contact substance instead of 
platinized asbestos. 

Other processes. — Sulphuric acid may be obtained by other pro- 
cesses, as by distilling the ferrous sulphate resulting from the 
natural oxidation of iron pyrites by air; but it is not so made at 
the present day. Ferrous sulphate was formerly called green 
vitriol, and the distilled product was called oil of vitriol in allusion 
to its consistence and origin. 

Purification. — Commercial sulphuric acid, prepared by the 
chamber process, may contain arsenic compounds, nitrous com- 
pounds, and salts (lead sulphate, etc.). Arsenic may be detected 
by the hydrogen test (p. 179), or the stannous chloride test (p. 182), 
nitrous compounds by means of powdered ferrous sulphate (which 
acquires a violet tint if they are present), and salts by observing 
the residue left on boiling some of the acid to dryness in a cruci- 
ble in a fume-cupboard. If only nitrous compounds are present, 
the acid may be purified by heating with about one-half per- 
cent, of ammonium sulphate — water and nitrogen being pro- 
duced (Pelouze). If arsenic compounds be present, heat with a 
small quantity of nitric acid (or sodium nitrate), which converts 
arsenous anhydride, As^Og, into arsenic anhydride, AS2O., then 
add ammonium sulphate, and distil, on a sand bath, in a retort 
containing a few small pieces of quartz, or of platinum wire or 
foil (to prevent "bumping" — see p. 267). The arsenic anhydride 
remains in the retort (arsenous anhydride would be carried over 
with the sulphuric acid vajiors). The distillation frees the acid 
from other salts (such as NaHSO^ and PbS04) which are not 
volatile. Lead may be detected by adding to the concentrated 



SULPHATES. 293 

acid a few drops of hydrochloric acid, or a crystal of sodium ij 

chloride; the lead chloride precipitated gives a peculiar pearly j 

opalescence to the liquid. ;f 

Pure sulphuric acid, HgSO^, has sp. gr. 1.833. The best ''oil i 

of vitriol' ' of commerce, a colorless liquid of oily consistence, has 
sp. gr. 1.8263, and contains about 92.5 percent, of hydrogen sul- | 

phate. The latter is Acidum Sulphuricum, U. S. P., Acidum Sul- J 

phuricum Dilutum, B. P. (sp. gr. 1.067) contains about 10 percent, 
of hydrogen sulphate. Acidum Sulphuricum Aromaticum, U. S. P. i 

an acid diluted with alcohol and mixed with tincture of ginger j, 

and oil of cinnamon, also contains about 20 percent, of hydrogen | 

sulphate. Aromatic sulphuric acid may contain sulphovinic acid in 
varying quantity, dependent upon the internal and external 
temperature during and subsequent to preparation, the age of the 
sample, etc. There are some definite compounds of sulphuric acid 
with water; one of these (HgSO^, H2O) may be obtained in crys- 
tals. 

Sulphuric anhydride, SOg, occurs in white crystals which interact 
with water with great violence, and produce sulphuric acid. As 
well as by the direct union of sulphurous anhydride and oxygen, 
it may be made by distilling sulphuric acid with phosphoric anhy- 
dride : H^SO, 4- P2O5 = 2HPO3 + SO3. It unites with sulphuric 
acid to form "fuming sulphuric acid" or pyrosulphuric acid, HgSgO^, 
formerly made at Nordhausen, in Saxony, by distilling partially 
dried and oxidized ferrous sulphate. 

Note. — Sulphuric acid is a most valuable compound to all 
chemists and manufacturers of chemical substances. By its 
agency, direct or indirect, a very large number of chemical trans- 
formations are effected. 

Analytical Reaction of Sulphates. 

1. To a solution of a sulphate add solution of a barium 
salt; a white precipitate of barium sulphate, BaSO^, is pro- 
duced. Add nitric acid and boil ; the precipitate does not 
dissolve. 

This reaction is as highly characteristic of sulphates as it has 
been stated to be of barium salts (see p. 110). The only error 
likely to be made in its application is that of overlooking the fact 
that barium nitrate and chloride are less soluble in concentrated 
nitric (or hydrochloric) acid than in water. On adding the barium 
salt to an acid liquid, therefore, a white precipitate may be 
obtained, which is simply barium nitrate (or chloride). The 
appearance of such a precipitate differs considerably from that of 
the barium sulphate, but should any doubt exist, water may be 
added, which will dissolve the nitrate or chloride, but will not 
aff'ect the sulphate. 



294 THE ACID RADICALS. 

2. Mix a fragment of au insoluble sulphate {e.g. BaSO^) 
with potassium or sodium carbonate, or, better, with a mix- 
ture of both carbonates, and fuse in a small crucible. Digest 
the residue, when cold, in water, and filter ; the filtrate may 
be tested for the sulphuric radical. 

This is a convenient method of qualitatively analyzing insolu- 
ble sulphates, such as those of barium and lead. 

3. Mix a fragment of an insoluble sulphate with sodium 
carbonate on a piece of charcoal, taking care that some of the 
charcoal dust is included in the mixture. Heat the mixture 
in the blow-pipe flame until it fuses, and, when cold, add a 
drop of acid; hydrogen sulphide is evolved, recognizable by 
its odor. 

This is another process for the recognition of insoluble sulphates. 
Other preparations of sulphur, and sulphur itself, give a similar 
result. It is therefore rather a test for sulphur and its compounds 
than for sulphates only. 

Antidotes. — In cases of poisoning by sulphuric acid, solution of 
sodium carbonate (common washing soda), magnesia and water, 
etc., may be administered as antidotes. 

Thiosulphuric Acid, H^S^Og, and other Thiosulphates. 

The only thiosulphate of much interest in pharmacy is sodium 
thiosulphate, Na^SPg, bHp (Sodii Thiosulphas, U. S. P.). It 
was formerly known as sodium hyposulphite, and is used in photo- 
graphy under the name of "hypo." (True hyposulphites are now 
known, e.g. Na2S20^.) 

Thiosulphates may be regarded as sulphates in which one-fourth 
of the oxygen has been replaced by sulphur. Thiosulphuric acid 
has not been isolated. 

Preparation of sodium- thiosulphate. — Heat together gently, or set 
aside in a warm place, a mixture of solution of sodium sulphite 
(Na2S03) and a little powdered sulphur ; combination slowly takes 
place, and sodium thiosulphate is formed. The solution, filtered 
from excess of sulphur, readily yields crystals. (The solution of 
sodium sulphite may be made by saturating solution of sodium 
hydroxide with sulphurous anhydride.) Sodium thiosulphate is 
obtained on the manufacturing scale by the interaction of sodium 
sulphate with the calcium thiosulphate formed by the action of 
atmospheric oxygen and carbonic anhydride on the waste cal- 
cium sul})hide from the Leblanc soda process. 

Uses of sodium thiosulphate in quantitative analysis. — In the 
Pharmacopoeia, sodium thiosulphate is given as a reagent for the 



PERSULPHATES. 295 

quantitative determination of free iodine in volumetric analysis. 
To a few drops of iodine solution add cold starch mucilage ; a deep- 
blue color (starch iodide), is produced. To the product add solu- 
tion of sodium thiosulphate until the blue color just disappears. 
This reaction is sufficiently definite and delicate to admit of appli- 
cation for quantitative purposes. It depends on the combination 
of iodine with half of the sodium of the thiosulphate to form sodium 
iodide, while sodium tetrathionate, NagS^Og (from rerpa, tetra, four, 
and Qelov, theion, sulphur), is formed at the same time. 

2Na,S,03 + I2 = 2NaI + Na^S.Og 

Use of '^Hypo" in Photography. — Sodium thiosulphate is 
largely used in photography to dissolve silver chloride, bro- 
mide, or iodide off plates which have been exposed in the camera 
and developed. Prepare a little of silver chloride by adding 
a chloride (sodium chloride) to a few drops of solution of sil- 
ver nitrate. Collect the precipitated chloride on a filter, 
wash, and add a few^ drops of solution of sodium thiosulphate ; 
the silver salt dissolves, solution of sodium silver thiosulphate 
being formed. The solution of this thiosulphate has a re- 
markably sweet taste, sweeter than syrup if the solution is con- 
centrated. Sodium gold thiosulphate has been employed for 
giving a pleasant tint to photographic prints. 

Test — To solution of a thiosulphate add a few drops of dilute 
sulphuric or other acid and smell the mixture ; thiosulphuric 
acid is set free, but at once begins to decompose into sulphur- 
ous anhydride, recognizable by its odor, free sulphur, and 
water (H^S.Og =. SO, + S + H^). Another test for a 
thiosulphide in solution is its power of dissolving silver chloride 
with production of a more or less sweet liquid. 



Persulphuric Acid, H^S^Og, and other Persulphates. 

Persulphuric anhydride, S^., was obtained by Berthelot in 1887. 
It yields a solution in water which probably contains some persul- 
phuric acid but soon decomposes giving oxygen and sulphuric acid. 

Salts of persulphuric acid was first prepared by H. Marshall in 
1891, potassium persulphate, K,S.,Og, and ammonium persulphate, 
(NHJ^^Pg, being obtained by' the electrolysis of saturated solu- 
tions of potassium sulphate and of ammonium sulphate, respectively, 
in dilute sulphuric acid. Barium persulphate can be prepared by 
the interaction of barium hydroxide with a saturated solution of 
ammonium i)ersulphate and evaporation of the solution in vacuo. 

The persulphates are of some industrial importance as bleaching 
and general oxidizing agents, and in the latter capacity they serve 



296 TEE ACID RADICALS. 

a number of purposes in cliemical analysis. Their solutions dis- 
solve various metals, such as zinc, magnesium, aluminium, copper, 
etc., without the evolution of any gas, sulphates being formed': 
Zn + KgS.Og = ZnSO, + K^SO^. Potassium persulphate was 
put upon the market some time ago, under the name of ' 'anthion " 
as a hypo-eliminator in photography, a purpose for which it is 
however, quite unsuitable. It is sparingly soluble in water. Ammo- 
nium persulphate has also found useful application in photography 
as a ' 'reducer. ' ' Sodium persulphate is obtained by the action of 
sodium hydroxide on ammonium persulphate, or by the electroly- 
sis of a saturated solution of acid sodium sulphate ; under the name 
ypersodine" an aqueous solution of the salt has been introduced 
into medicine as an aperitive and eupeptic. 

Analytical Bead ions of Persulphates.— In presence of moisture 
persulphates gradually decompose with formation of sulphate and 
evolution of oxygen, ^K^SPg -f 2K^0 = 4KHS0, + 0^ ; con- 
sequently most solutions, unless freshly prepared from pure per- 
sulphate, give a white precipitate on the addition of barium nitrate; 
pure solutions give a precipitate of sulphate slowly, on boiling. 
— Hydrochloric acid is decomposed slowly in the cold but rapidly 
on w^arming, with evolution of chlorine, KgS^g + 2HC1 = 
2KHS0^ -f Clg. — Potassium iodide is similarly decomposed, 
with liberation of iodine. — Sulphuric acid, on warming, causes 
decomposition of oxygen and ozone. — Ferrous sulphate is con- 
verted into ferric sulphate, the solution becoming dark reddish 
brown when hot. K^S^Og + 2FeS0, = K^SO, -f Ye^{^0,)^.— 
In solutions which are not too acid, silver nitrate produces a more 
or less marked black precipitate of the silver salt (AgHSO^) of 
another sulphur acid (Caro'sacid, monopersulphuricacidjH.^SOg). 
The precipitate increases in quantity if sulf)huric acid liberated 
during its formation is neutralized by means of potassium hydroxide. 
Sulphur Oxyacids. — The formulae of the oxyacids of sulphur 
afford a series that is as useful as the series of compounds of nit- 
rogen and oxygen in illustrating Dalton's law of multiple propor- 
tions. 



Sulphurous Acid . . H2SO3 

Sulphuric Acid . . H.SO^ 

Thiosulphuric Acid . HgSgOg 

Hypsolphurous Acid . HgSp^ 

Persulphuric Acid, Il2S20g 
Monopersulphuric Acid, H2SO5. 



Dithionic Acid . . Il2S20g 

Trithionic Acid . . H2S3O, 

Tetrathionic Acid . . HgS^Op 

Pentathionic Acid . HjSgOg 



QUESTIOXS AXD EXERCISES. 

State the formula and molecular weight of sulphuric acid. — How is it 
related to other sulphates ? — Write a short article ou the manufacture of 



CARBONATES. 297 

sulphuric acid, giving equations. — How may nitrous compounds be detec- 
ted in, and eliminated from, sulphuric acid?— State the methods for 
detecting arsenic in sulphuric acid, and explain the process by which it 
may be removed. — Define sulphates, acid sulphates, and double sulphates. 
— What percentage of hydrogen sulphate is contained in oil of vitriol ? — 
By what process is sulphuric anhydride obtained from ordinary sulphuric 
acid ? — Explain the reactions which occur in testing for sulphates. — Calcu- 
late the weight of sulphuric acid, of 96.8 percent., necessary for the pro- 
duction of one ton of dry ammonium sulphate. Ans. 1718 lbs. — ^Name the 
antidotes in cases of poisoning by sulphuric acid. — Illustrate by an equa- 
tion the preparation of sodium thiosulphate. — Mention the characteristic 
reactions of sodium thiosulphate. — Give the names and formulae of ten 
acids, each containing hydrogen, sulphur, and oxygen, 



CARBONIC ACID [H^COg], AND OTHER CARBONATES. 

Occurrence and varieties of Carbon. — Carbon is a constituent of 
all living organisms, and the blackening which is observed when 
plant or animal tissues and the majority of the many products 
obtained from such tissues are sufficiently strongly heated, is due 
to the separation of carbon in a more or less pure form. Coke, 
charcoal, soot, lamp-black, etc., consist of amphorous carbon 
mixed with varying quantities of mineral or other impurities derived 
from the materials from which these substances have been formed. 
When coal or wood is subjected to dry distillation (see p. 131) in 
iron retorts for the preparation of coal-gas, coke, charcoal, etc., 
water and other volatile products (including marsh gas, carbonic 
anhydride, and carbonic oxide, all of which contain carbon) are 
given off in considerable quantity while the greater proportion of 
the carbon of the coal or wood remains in the retorts. 

Bone-black, or Animal (Charcoal, Carbo Animalis, U. S.P.), 
is the residue obtained on subjecting dried bones to a red heat 
without access of air. It is a mixture of about 9 parts of 
mineral with 1 of carbonaceous matter. The operation may 
be carried out on a small scale by heating a few fragments ojf 
bone in a covered porcelain crucible in a fume-cupboard until 
smoke and vapor are no longer evolved. The mineral matter 
may be removed and purified animal charcoal ( Carbo Ani- 
malis Perificatus, U. S. P.), obtained as follows : Boil 
powdered animal charcoal with a mixture of twice its weio-ht 
of hydrochloric acid and four times its own weight of water ; 
add boiling water and filter ; again boil the drained residue 
with half as much of the diluted acid as was previously em- 
ployed ; again filter ; wash the residual charcoal with distilled 
water until the washings give little or no turbidity with solu- 
tion of silver nitrate ; dry the product in a warm place. It 



298 THE ACID RADICALS. 

should not yield more than 10 percent, of moisture when dried 
at a high temperature, nor more than 4 percent, of ash when 
thoroughly incinerated. Thirty grains well shaken with 15 
ounces of distilled water containing 0.005 percent, of ordinary 
commercial caramel (see Index) should remove at least four- 
fifths of the color from the liquid. (Hodgkin.) 

Wood Charcoal ( Carbo Ligni, U . S. P. ), is a wood similarly 
ignited without access of air. On incineration it should yield not 
more than 7^ percent, of ash. 

Decolorizing power of Animal Charcoal. — Animal charcoal, in 
fragments is employed in decolorizing solutions of common brown 
sugar, for the production of white sugar. Its power, and the nearly 
equal power of an equivalent quantity (xo^h) of the purified variety, 
may be demonstrated on solution of litmus or logwood as well as 
on solution of caramel. 

Besides these amorphous varieties of carbon there are two crys- 
talline varieties ; namely plumbago or black-lead, the material 
employed in making the cores of the so-called ''lead" pencils, 
which crystallizes in hexagonal plates, and diamond which crys- 
tallizes in forms belonging to the cubic system. Diamond is the 
hardest substance known. When any form of carbon is burned 
in oxygen, carbonic anhydi-ide, CO,, results. 

Carbonates are very common in nature, calcium carbonate, 
CaCOg, being widely distributed as chalk, limestone, and marble. 
Hydrogen carbonate (true carbonic acid) is not known as a sepa- 
rate substance, but a solution of carbonic anhydride in water 
appears to contain some of this acid. Such a solution {see below) 
changes the color of blue litmus-paper, but the change is only 
temporaiy, as the carbonic acid decomposes into water and car- 
bonic anhydride when the paper is exposed to the air for a short 
time. 

Carbonic anhydride, CO2, is a product of the combustion of all 
carbonaceous matters, and of the respiration of animals and plants. 
It is a constant constituent of the atmosphere, in which it is 
present to the extent of about 8 parts in 10,000, and throughout 
which it is very equally distributed by diffusion {see p. 30). The 
process of carbon assimilation in the vegetable kingdom is depend- 
ent upon the presence in the air of this small proportion of 
carbonic anhydride, and it takes place by the aid of chlorophyll, 
the green coloring matter of plants, under the influence of direct 
sunlight. The accumulation of carbonic anhydride in confined 
air, so as to greatly exceed the proportion just mentioned, gives 
to such air (in crowded rooms, for example) depressing effects ; 4 
or 5 percent, rendering the atmosphere poisonous when taken into 
the blood from the lungs. Carbonic anhydride (or carbonic acid, 
which is present to some extent at least in all aqueous solutions 



CARBONATES. 299 

of carbonic anhydride) may, however, be taken into the stomach 
with beneficial sedative effects ; hence, probably, much of the 
value of such effervescing liquids as aerated water (often wrongly 
called soda-water), lemonade, solutions of the various granulated 
preparations and effervescing powders, and even potash-water and 
soda-water properly so-called. The gas liquefies on the applica- 
tion of sufficient pressure at temperatures below 31° C, and the 
liquid solidifies when still further cooled to —58° C, The relative 
weights of equal volumes of carbonic anhydride, air, and hydro- 
gen, are respectfully 21.89, 14.44, and 1. At ordinary tempera- 
tures, water dissolves about its own volume of carbonic anhydride, 
and the weight of the gas dissolved under increased pressure is 
proportional to the pressure. An average bottle of aerated water^ 
contains about five times the quantity of carbonic anhydride which 
the water could dissolve without artificial pressure, and when the 
cork or stopper is removed, about four-fifths of this quantity 
escapes, while the balance (about equal in volume to the volume 
of the water) remains dissolved. 

The carbonic anhydride used in the manufacture of sodium 
carbonate (the carbonate most frequently used in medicine and in 
the arts generally) is obtained by the decomposition of calcium 
carbonate (see p. 87). 

Carbonic Oxide, CO. — Heat in a test-tube two or three frag- 
ments of potassium ferrocyanide with eight or ten times their 
weight of sulphuric acid, and as soon as the gas begins to be 
evolved, remove the test-tube from the flame, as the action, when 
once set up, proceeds somewhat tumultuously. Ignite the car- 
bonic oxide at the mouth of the tube ; it burns with a pale-blue 
flame, the product of combustion being carbonic anhydride, COg. 
Carbonic oxide may also be obtained from oxalic acid (see p. 
304). 

Carbonic oxide is a direct poison. It is generated whenever 
coke, charcoal, or coal burns with an insufficient supply of air. 
Hence the danger of burning charcoal in braziers (otherwise than 
under chimneys) in the more or less closed apartments of ordinary 
dwellings. 

Phosgen. — Carbonic oxide unites with chlorine in sunlight to 
form phosgen (^w^, pAo.s, light, and yewau, gennao, I produce), 
COClg, a colorless liquid which interacts readily with water, 
forming hydrochloric acid and carbonic anhydride, CO + CI2 = 
COCI2 ; CbCl^ + H^O = 2HC1 + CO^. 



^Bottled aerated waters yield carbonic anhydride tuniultnously when 
new, and soon become "flat," but yield it less rapidly and more continu- 
ously when older, and then retain palate-sharpness hmo-er. Possibly 
this is due to a solution of true carbonic acid [H2CO3I being- loss unstable 
than a mere solution of the gas, CO2. 



300 THE ACID RADICALS. 

Analytical Reactions of Carbonates. 

1. To a fragment of marble iu a test-tube add dilute 
hydrochloric acid ; carbonic anhydride, CO^, is evolved, and 
may be conveyed into water or solutions of salts by the usual 
delivery-tube. 

This is the process usually adopted in preparing carbonic anhy- 
dride for experimental purposes. On the large scale, the gas is 
prepared from chalk or marble and sulphuric acid, frequent stir- 
ring promoting its liberation. 

2. Pass the gas into lime-water ; a white precipitate of 
calcium carbonate, CaCOg, is produced. Solution of lead 
subacetate may be used instead of lime-water, and is perhaps 
even a more delicate reagent. 

The evolution of an odorless gas on the addition of an acid to a 
salt, heat being applied to the mixture if necessary, and the form- 
ation of a white precipitate when the gas is passed into lime-water, 
afford sufficient evidence of the presence of a carbonate. The 
presence of carbonates in solutions of alkali-metal hydroxides 
may be detected by the addition of lime-water. Carbonates in 
presence of sulphites or thiosulphates may be detected by adding 
acid potassium tartrate, which decomposes carbonates with effer- 
vescence, but does not attack sulphites or thiosulphates ; or the 
substance under examination may first be mixed with excess of 
potassium dichromate, and dilute sulphuric or hydrochloric acid 
be then added. The evolution of sulphurous anhydride, from the 
decomposition of any sulphite or thiosulphate, is entirely pre- 
vented by the presence of the dichromate (which would immedi- 
ately oxidize it to sulphuric acid) while the evolution of carbonic 
anhydride is not interfered with. 

3. Blow air from the lungs through a glass tube into lime- 
water ; the presence of carbonic anhydride is at once indicated 
by the liquid becoming turbid. By passing a considerable 
quantity of ordinary air through lime-water, a similar effect is 
produced. A bottle containing lime-water soon becomes inter- 
nally coated with calcium carbonate owing to absorption of 
atmospheric carbonic anhydride. 

4. Fill a dry test-tube with carbonic anhydride, passing the 
gas, by means of a delivery-tube, to the bottom of the test- 
tube. Being rather more than one and a half times as heavy 
as air (sp. gr. 1.529), it displaces the latter. Prove the 
presence of the gas in the test-tube by pouring it slowly, as if 



k 



CARBONATES. 301 

a visible liquid, into another test-tube containing lime-water ; 

the characteristic turbidity is obtained on shaking up the 

lime-water with the air of the tube. In testing for carbonates L 

by bringing the evolved gas into contact with lime-water, the 

preparation and adaptation of a delivery-tube may often be 

avoided by pouring the gas from the generating-tube into that 

containing the lime-water, in the manner just indicated. 

5. Pass carbonic anhydride through lime-water until the 
precipitate at first formed is dissolved. The resulting liquid 
is a solution of calcium carbonate in carbonic acid water, or 
probably calcium bicarbonate, CaH2(C03)2. Boil the solu- 
tion ; carbonic anhydride escapes, and the carbonate is again 
precipitated. 

This experiment serves to show how calcium carbonate is kept 
in solution in ordinary well-waters, imparting to them the prop- 
erty of * 'hardness," and how the fur or stone-like deposit in tea- 
kettles and boilers is formed. It should here be stated that 
calcium sulphate also produces hardness, and that calcium 
carbonate and sulphate with small quantities of magnesium car- 
bonate and sulphate, constitute the hardening constituents of 
well-waters, a curd (calcium or magnesium oleate) being formed 
whenever soap is used with such waters. As the formation of 
this curd indicates the formation from the soap of insoluble sub- 
stances which are devoid of detergent properties, it is obviously 
important, in order to avoid waste of soap, that water as free as 
possible from these hardening constituents should be employed for 
washing purposes. The hardness produced by the calcium and 
magnesium carbonates is termed "temporary hardness," because 
removable by ebullition ; that produced by the sulphates "perma- 
nent hardness," because unaffected by ebullition. The addition 
of lime-water, or a mixture of lime and water, removes tempor- 
ary hardness, CaH,(C0,)2 + Ca(OH).^ = 2CaC03 + 2H2O, and 
sodium carbonate, "washing-soda," removes both temporary and 
permanent hardness, in the latter case sodium sulphate remaining 
in solution. Barium carbonate (powdered witherite) also decom- 
poses calcium and magnesium sulphates, barium sulphate being 
precipitated and calcium and magnesium carbonates formed; the 
latter and the carbonates originally present in the water may then 
be precipitated by ebullition or by the action of lime-water. But 
the poisonous character of barium salts prevents the use of barium 
carbonate to purify water for drinking purposes, as by accident 
or an unforeseen reaction a portion might become dissolved. 

6. Add a solution of potassium or sodium carbonate to a 
magnesium salt ; a white precipitate of a basic magnesium 



302 THE ACID RADICALS. 

carbonate is produced, but the precipitation is not complete. 
On boiling the substance formerly known as magnesia alba 
is precipitated (see p. 124). 

Thiocarbonates or Sulphocarbonaies resemble carbonates in com- 
position, but contain sulphur in place of oxygen. 

Thiocarboriic or Sulphocarbonic anhydride, CSg, commonly termed 
carbon disulphide or bisulphide {Carbonei Disulphidum, U. S. P.), 
is a highly volatile and inflammable liquid, easily made from its 
elements. Sp.gr. 1.256 to 1.257; boiling-point, 46° to 47° C. 
When pure it is almost odorless, but a commercial specimen, or 
the pure liquid which has been exposed to light for some time, 
possesses a disagreeable odor due to impurity. Impure specimens 
may be rendered almost odorless by digestion with lime and then 
with copper turnings, or by digesting and distilling with mercuric 
chloride. It often contains dissolved sulphur. It is slightly solu- 
ble in water (about 1 in 400) forming a useful antiseptic fluid. 
Carbon monosulphide, analogous to carbon monoxide (carbonic 
oxide), is said to have been obtained. 



QUESTIONS AND EXERCISES. 



Explain the action of hydrochloric acid on animal charcoal in the pro- 
cess of purification of the latter. — Name the chief natural carbonates. — 
What are the formulae of carbonic acid and carbonic anhydride? — Adduce 
evidence of the existence of true carbonic acid. — Carbonic anhydride is 
constantly exhaled from the lungs of animals ; why does it not accumu- 
late in the atmosphere ? — State the specific gravity of carbonic anhydride. 
— By what process may carbonic anhydride be obtained for experi- 
mental and manufacturing purposes? — Describe the action of carbonic 
anhydride on potassium or sodium carbonate. — How may carbonic anhy- 
dride be detected in expired air? — To what extent is carbonic anhydride 
heavier than air?— Calculate what quantity of chalk (90 percent, pure) 
will be required to furnish the carbonic anhydride necessary to convert 
one ton of potassium carbonate (containing 83 percent, of K2CO3) into 
bicarbonate, supposing no gas to be wasted. Ans., 1500 lbs. — Define "hard- 
ness" in water. — How may the presence of carbonates be demonstrated? 



OXALIC ACID, H^C,0^,2H^0, AND OTHER OXALATES. 

Sources. — Oxalates occur in nature in the juices of some plants, 
as wood-sorrel, rhubarb, the common dock, and certain lichens; 
but hydrogen oxalate and other oxalates are all made artificially. 
The carbon of many organic substances yields oxalic acid when 
those substances are boiled with nitric acid, and alkali-metal oxa- 
lates when they are roasted with a mixture of potassium and 
sodium hydroxides. 



OXALATES. 303 

Experimental process. — On the small scale, a mixture of nitric 
acid 10 parts, loaf-sugar 2 parts, and water 3 parts, quickly yields 
oxalic acid. Red fumes are at first evolved abundantly, and crys- 
tals are deposited on cooling. A more dilute nitric acid, kept 
warm, acts more slowly, but yields more oxalic acid. The follow- 
ing process is more economical. 

Manufacturing p7'ocess. — On the large scale, sawdust is roasted 
with caustic soda, the resulting sodium oxalate decomposed by 
means of slaked lime, with regeneration of caustic soda and forma- 
tion of calcium oxalate. The latter is digested with sulphuric 
acid, and the liberated oxalic acid is purified by recrystallization. 

Purified oxalic acid. — The acid made from sugar, recrystallized 
two or three times, is quite pure. Commercial oxalic acid should 
be mixed with insufficient water for complete solution, and the 
mixture occasionally shaken ; most of the impurities, remain undis- 
solved, and the saturated aqueous solution on evaporation yields 
crystals which are nearly pure. Aqueous solutions of oxalic acid 
slowly decompose under the influence of light and oxygen. 

Quantivalence. — The acid radical of the oxalates is bivalent 
(CgO/^. The formula of oxalic acid is frequently written (COOH).^, 
2H2O. Both normal oxalates (R\C.f)^ and acid oxalates 
(R^HCpj are known. 

Salt of sorrel is a crystalline salt intermediate in composition 
between oxalic acid and acid potassium oxalate, the crystals con- 
taining two molecules of water of crystallization (KHgCO^, H.fifi^, 

Analytical Reactions of Oxalates. 

1. To solution of an oxalate (e.g., ammonium oxalate) add 
solution of calcium chloride ; a white precipitate of calcium 
oxalate, CaC20^, is produced. Add to the precipitate excess 
of acetic acid ; it is insoluble. Add hydrochloric acid ; the 
precipitate dissolves. 

The formation of a white precipitate on adding a calcium or 
barium salt, insoluble in acetic but soluble in hydrochloric or 
nitric acid, is usually sufficient proof of the presence of an oxa- 
late. It should be noted, however, that in the presence of sul- 
phates, calcium chloride may produce a precipitate of calcium 
sulphate which is only slightly soluble in acetic, but is readily 
soluble in hydrochloric, acid. In the known presence of sulphates, 
oxalate may be tested for by the addition of calcium sulphate to a 
solution acidulated with acetic acid only. 

2. Heat a fragment of an alkali-metal oxalate (potassium 
oxalate, for example) in a test-tube ; decomposition occurs 



304 THE ACID RADICALS. 

(accompanied by only a slight darkening), carbonic oxide, 
CO, is liberated, and carbonate of the metal remains. Add 
dilute hydrochloric acid to the residue ; effervescence occurs. 

This is a ready test for most ordinary oxalates, soluble or insolu- 
ble, and is trustworthy if, on heating the substance, no charring 
occurs, or not more than gives a gray color to the residue. Organic 
metallic salts decompose when heated, and leave a residue of car- 
bonate, but, except in the case of oxalates, the residue is nearly 
always accompanied by much carbon. Insoluble oxalates and 
organic salts of such metals as lead and silver are, of course, liable 
to be reduced to oxide or even to metal by the action of heat. 
Such oxalates may be decomposed by boiling with solution of sodium 
carbonate, and the filtered liquid may be tested for oxalate by 
the calcium chloride test (or by means of calcium sulphate, in 
acetic acid solution). 

Other Analytical Reactions. — Silver nitrate gives, with oxa- 
lates, a white precipitate of silver oxalate, Ag.^C^O^. — Dry 
oxalates are decomposed when heated with concentrated sul- 
phuric acid, carbonic oxide and carbonic anhydride escaping. 
If enough oxalate be employed, the gas may be washed with 
a caustic alkali, which removes the carbonic anhydride, and 
the carbonic oxide may then be ignited ; it will be found to 
burn with a characteristic bluish flame. — Oxalates, when 
mixed with water, black manganese oxide (free from carbon- 
ates), and sulphuric acid, yield carbonic anhydride which may 
be indentified by means of lime-water in the usual manner. 
— Not only such insoluble oxalates as those of lead and 
silver above referred to, but any ordinary insoluble oxalate, 
such as that of calcium or magnesium, may be decomposed by 
prolonged ebullition with solution of sodium carbonate ; after 
filtration the oxalic acid radical will be found in the filtrate 
as soluble sodium oxalate. 

Antidote. — In cases of poisoning by oxalic acid or salt of sorrel, 
chalk and water may be administered as antidote (with the view 
of ijroducing insoluble calcium oxalate), emetics and the stomach- 
pumj), or stomach-siphon, being used as soon as possible. 



QUESTIOXS AND EXERCISES. 

How ux-e oxalates obtained ? — What is the quautivaleuce of the oxalic 
radical?— Give the formula of "salt of sorrel."— Mention the chief test for 
oxalic acid and other soluble oxalates.— By what reactions are insoluble 
oxalates recognized? — Xame the antidote for oxalic acid, and describe its 
action. 



TARTRATES. 



TARTARIC ACID, H,C,H^O^, AND OTHER TARTRATES. 

Sources. — Tartrates exist in the juices of many fruits ; but it is 
from that of the grape tliat our supplies are usually obtained. 
Grap-juice contains much acid potassium tartrate, KHC^H^O^, 
which is gradually deposited when the juice is fermented, as in 
making wine; for while acid potassium tartrate is not very solu- 
ble in water, it is still less so in spirituous liquids, and hence it crys- 
tallizes out as the sugar of the grape-juice is gradually converted 
into alcohol. It is found, mixed with calcium tartrate, lining the 
vessels in which wine is kept; and it is from this crude substance, 
termed argal or argol, also from the albuminoid yeasty matter or 
"lees" deposited at the same time, as well as from any tartrate 
that may remain in the marc left after the juice has heen pressed 
from the grapes, that, by rough recrystallization, '* tartar, " still 
containing 6 or 7 percent, or more of anhydrous calcium tartrate, 
CaC^H^Og, is obtained. From the tartar, tartaric acid and other 
tartrates are prepared. In old dried grapes (raisins) crystalline 
masses of tartar and of grape-sugar are frequently met with. 

Verjuice, that is, verd }mce or green juice, is an old name for the 
very sour juice of unripe green grapes and of crab apples. It con- 
tains tartaric, racemic, and malic acids. 

Cream of tartar, purified by crystallization {Potassii Bitartras, 
U. S. P. ), occurs as a gritty white powder, or slightly opaque rhom- 
bic crystals ; of a pleasant acid taste, soluble in 200 parts of cold 
and 16.7 of boiling water, insoluble in alcohol.^ 

Quantivalence. — The acid radical of the tartrates is bivalent 
(C^H^O/O, and both normal tartrates (R\QJlfi^ and acid tar- 
trates (R^HC^H^Og) are known. Potassium tartrate (K.^C^H^^)^, 
H^O, and Rochelle salt, potassium and sodium tartrate, the official 
Potassii et Sodii Tartras, are illustrations of normal tartrates, while 
cream of tartar, KHC^H^Op, is an example of an acid tartrate. 
Constitutional formula of tartaric acid : C2H2(OH)^(COOH)2. 



Tartaric Acid. 

Tartaric Acid [Acidum Tartaricum, U. S. P.), is obtained by 
boiling cream of tartar with water, adding chalk till effervesence 
ceases, and then calcium chloride so long as a precipitate is pro- 

1 A boiling solution of tartar yields a floating crust of minute crystals on 
cooling — ^just as milk j'ields a floating layer of cream; hence the term 
cream of tartar. " It is called tartar,''^ says Paracelsus, " because it produces 
oil, water, tincture, and salt, which burn the patient as tartarus does." 
Tartarus is Latin (Tdprapo^, Tartaros, Greek) for hell. The products of its 
destructive distillation are certainly somewhat irritating in taste and 
smell ; and the " salt " (potassium carbonate) that is left is diuretic and iu 
larger quantities powerfully corrosive. 

20 



306 THE ACID RADICALS. 

duced ; the two portions of calcium tartrate thus consecutively 
formed are thoroughly washed, treated with dilute sulphuric acid, 
the mixture boiled for a short time, the resulting calcium sulphate 
mostly separated by filtration, the filtrate concentrated by evapor- 
ation, any further calcium sulphate that may have deposited 
removed as before, and evaporation continued until the solution 
is sufliciently concentrated to crystallize on cooling. The calcium 
tartrate obtained from nine ounces of cream of tartar requires five 
ounces (by weight) of sulphuric acid for complete decomposition. 

SKHC^HPe + CaCOa = CaC,H,0, + K2C,H40, + Hp + CO^ 

Acid potassium Calcium Calcium Potassium Water Carbonic 

tartrate carbonate tartrate tartrate auhydride 

K^C.HP, + CaCl2 = CaC,H,0, + 2KC1 
Potassium Calcium Calcium Potassium 

tartrate chloride tartrate chloride 

CaC,H,Oe + H^SO, = CaSO, + H^C.Hp^ 

Calcium Sulphuric Calcium Tartaric 

tartrate acid sulphate acid 

Tartaric acid occurs in commerce in colorless crystals or in finely 
crystalline powder. It is readily soluble in water and in alcohol. 
One gramme dissolved in 8 Cc. of water forms Tartaric Acid Test 
Solution, U. S. P. Aqueous solution of tartaric acid is not stable. 

Parcels of tartaric acid often contain crystals of a physically 
isomeric modification [see Isomerism). It is termed paratartaric 
acid (Tvapa, para, beside) or racemic acid (racemus, a bunch of 
grapes), and is a combination of ordinary tartaric acid, whose solu- 
tion rotates a ray of polarized light to the right (dextrotartaric or 
right-rotating tartaric acid), with laevotartaric or left-rotating tar- 
taric acid, whose solution rotates a polarized ray to the left. ^ Race- 
mic acid is inactive in this respect (optically inactive), the opposite 
properties of its constituents neutralizing each other. Eacemic 
acid is less soluble in alcohol than tartaric acid. 

Potassium Tartrate. (See p. 78). 

Potassium and Sodium Tartrate. Rochelle Salt. 

(See p. 91). 

Tartar Emetic. (See p. 188). 

Compound Effervescing Powder, {Pulvis-Efferveecens Compositus, 
U. S. P.), ox Seidlitz Powder, consists of Rochelle salt (120 grains) 
with 40 grains of sodium bicarbonate (the mixture usually wrapped 

1 According to Van 't Hoff and Le Bell, all compounds that cause such 
rotation contain at least one atom of carbon with which four different 
atoms or radicals are united. Such carbon atoms are termed asymmetric. 



TARTRATES. 307 

in blue paper) and 34.7 grains of tartaric acid (wrapped in white 
paper). When administered, one powder is dissolved in a tumbler 
rather more than half full of water, the other added, and the mix- 
ture drunk during effervescence. 

Analytical Reactions of Tartrates. 

1. To a solution of any neutral tartrate, or of tartaric acid 
made neutral by addition of sodium hydroxide solution, add 
solution of calcium chloride ; a white precipitate of calcium 
tartrate, CaC^H^Og, is produced. Collect the precipitate on a 
filter, wash, place a small quantity in a test-tube, and add solu- 
tion of potassium hydroxide : on stirring the mixture the pre- 
cipitate dissolves. Heat the solution : the calcium tartrate is 
reprecipitated. 

In this reaction a moderate quantity of the calcium chloride solu- 
tion should be added at once, and the test should be performed 
without delay, otherwise the calcium tartrate will assume a crystal- 
line character and be with difficulty dissolved by the caustic pot- 
ash. The latter should be quite free from carbonate. 

The solubility of calcium tartrate in cold caustic potash solution 
enables the analyst to distinguish between tartrates and citrates, 
otherwise a difficult matter. Calcium citrate is not soluble, or only 
to a slight extent, in the alkali. The absence of much ammonium 
salt must be ensured, calcium citrate, as well as tartrate, being 
soluble in solutions of ammonium salts. 

2. Acidulate a solution of a tartrate with acetic acid, add 
potassium acetate, and well stir the mixture ; a crystalline 
precipitate of potassium bitartrate slowly separates. 

This reaction is not applicable in testing for very small quantities 
of tartrates, the acid potassium tartrate being not altogether insolu- 
ble. The precipitate being insoluble in alcohol, however, the 
addition of the latter renders the test much more delicate. 

3. To a neutral solution of a tartrate add solution of silver 
nitrate ; a white precipitate of silver tartrate, Ag.^C^H^O^, is 
produced. Boil the mixture ; the precipitate blackens owing 
to the reduction of the silver tartrate to metallic silver. Or, 
before boiling, add a drop, or less, of ammonia water ; a mirror 
will form on the tube — adhering well to the glass if the tube 
was thoroughly cleansed. When even an insoluble tartrate 
is placed in a dry tube with a few fragments of silver nitrate, 
and a drop, or less, of ammonia water is added, a mirror-like 



THE ACID RADICALS. 

character is imparted to each fragment of silver salt when the 
tube is gently rotated some inches above a Bunsen flame. 

Other Reactions. — Tartrates heated ^vith concentrated sul- 
phuric acid char immediately, or at least very rapidly. — Tar- 
taric acid and the soluble tartrates prevent the precipitation 
of ferric and other hydroxides on the addition of alkalies, solu- 
tions of double tartrates being formed (which on evaporation 
yield liquids that do not crystallize, but, when spread on sheets 
of glass, dry up to thin transparent plates or scales). Iron 
and Ammonium Tartrate {Ferri et Ammonii Tartras, U. S. P.) 
and Iron and Potassium Tartrate (Ferri et Potassii Tartras, 
U. S. P.) are preparations of this kind. — Metallic tartrates 
decompose when heated, carbon being set free and metallic 
carbonate (or metal in the case of easily reducible metals) 
formed, while the gaseous products possess a peculiar, more or 
less characteristic smell, resembling that of burnt sugar. 



QUESTIONS AND EXERCISES. 

State the origin of tartaric acid and other tartrates, and explain the 
deposition of argol, crude acid potassium tartrate, during the manufac- 
ture of Aviue. — Give the chemical formula, and the characters of "purified 
cream of tartar." — Mention the formula and quantivalence of the tartaric 
radical. — Write the formulae of a number of tartrates. — Give equations 
illustrating the production of tartaric acid from purified cream of tartar. 
— By what general process may normal or double tartrates be obtained 
from acid potassium tartrate ? — Give equations representing the reactions. 
— Enumerate the tests for tartrates, and describe the efiects of heat on 
metallic tartrates. 



CITRIC ACID, H,C.H.O., KO, AND OTHER CITRATES. 



■3-6 



Sources. — Citric acid {Acidum Citricum, U. S. P.) exists in the 
juice of the gooseberry, currant, cherry, strawberry, raspberry, and 
many other fruits, as w^ell as in other parts of plants. The pulp of 
the fruit of Tamarindus indica {Tamarindm, U. S. P.) contains 
from 1 to 12 percent, (in addition to 1.5 of tartaric acid, 0.5 of 
malic acid, and 3 percent, of acid potassium tartrate). But it is 
from the lemon or lime that the citric acid of commerce is usually 
obtained. For this purpose concentrated lemon-juice is exported 
from Sicily, concentrated bergamot-juice from the Calabrian coast 
of South Italy, and concentrated lime-juice from the West Indies. 

Citric acid may be prepared from lemon-juice by the following 
process : — The hot juice should be neutralized by the addition of 
powdered chalk, the resulting calcium citrate collected on a filter, 



CITRATES. 309 

washed with hot water till the liquor passes xioiii il colorless (by 
which not only the coloring-matter but the mucilage, sugar and 
other constituents of the juice are got rid of), then mixed with cold 
water, decomposed by means of sulphuric acid, the mixture b:»i^ed 
for half an hour, filtered, the solution evaporated to a density of 
1.21, set aside for 24 hours, then poured off from any deposit of 
crystalline calcium sulphate, farther concentrated and set aside to 
crystallize. If the quantity of calcium citrate decomposed is 
unknown, the sulphuric acid may be added until a little of the 
supernatant fluid gives, after a minute or two, a precipitate with 
solution of calcium chloride. The concentrated solution of citric 
acid generally crystallizes very slowly. Shaken violently, however, 
in a bottle with a granule or two of solid acid from a previous crys- 
tallization, it quickly yields its citric acid in a pulverulent form, 
and this drained and redissolved in a very small quantity of hot 
water yields crystals moderately quickly (Warington). 

2H3C,H50, + 3CaC03 = G2.,{C^B.p^\ + SH^ + 300^ 
Citric acid Calcium Calcium citrate Water Carbonic 

carbonate anhydride 

Ca3(C,H^0,), + 3H,S0, = SHsC.H^O, + 3CaS0, 
Calcium citrate Sulphuric acid Citric acid Calcium sulphate 

Citric acid is now manufactured by the citric fermentation of 
glucose, which takes place in presence of the fungi Citromijces 
Pfefferianus and C. glaber. 

The artificial production of citric acid has been accomplished by 
Grimaux and Adam, who, starting with glycerin, produce certain 
chloro- and cyano-derivatives and ultimately citric acid itself ; it 
has also been built up by starting with acetone. 

Citric acid itself is the only citric compound of much direct 
importance to the pharmacist. It usually occurs in colorless crys- 
tals soluble in . 4 of their weight of boiling and in . 54 of their weight 
of cold water, less soluble in alcohol and insoluble in ether. A 
solution of 30 to 40 grains in 1 ounce of water forms a substitute 
for lemon-juice. Syrupus Acidi aVHciis official. Citrates heated 
with concentrated sulphuric acid to about 215° F. (101.6° C.) 
evolve carbonic oxide, and at higher temperatures acetone and car- 
bonic anhydride. 

Action of heat on citric acid —Citric acid when slowly heated 
first loses its water of crystallization ; afterward (347° F., 'l75° C.) 
the elements of another molecule of water are evolved and a resi- 
due obtained from which either extracts actonic acid, YLf^.f)^, 
identical with the aconitic acid (and the acid first termed eguisefic) 
in various species of Aconium and Equisetum. 

Quant ivaleyice.— The acid radical of the citrates is trivalent 
(^6^50/^0- Three classes of citrates are known, in which one, 
two, or all three atoms respectively of the replaceable hydrogens 



:'^10 3'HE iCID RADICALS. 

•avoms 01 Lue acia, llgv^gll^O^, are replaced by equivalent propor- 
.ons of metallic radicals. Constitutional formula of citric acid, 
03H,(OH)(COOH)3. 

The official Lemon-juice (Limonis Succus, U. S. P.) is to be freshly 
expressed from the ripe fruit, to have a specific gravity of 1.030 to 
1.040, and to contain from 7 to 9 percent, of citric acid, (HgCgH^O^, 
HgO). The acidity may be ascertained by adding potassium hydrox- 
ide, V. s., till red litmus-paper is turned distinctly blue. Before 
applying this test to commercial specimens of lemon-juice, the 
absence of notable quantities of sulphuric, hydrochloric, acetic, 
tartaric, or other acid must be ensured by application of appropri- 
ate reagents. (See also " Lemon-juice " in Index). 

Lime-juice contains an average of 7. 84 percent, of citric acid, 
rarely rising to 10 percent, and very seldom falling to 7 percent. 
Containing but little sugar and mucilage, it requires no addition 
of alcohol to preserve it. Lemon-juice requires about 40 percent, 
of proof spirit to prevent fermentation (Conroy). 

Analytical Reactions of Citrates. 

1. To a dilute solution of any neutral citrate, or of citric 
acid carefully neutralized by addition of potassium hydroxide, 
add solution of calcium chloride and boil; a white precipitate 
of calcium citrate, Csi^^Cfifi^)^, is produced. Treat the 
precipitate as described in the case of calcium tartrate (p. 307) ; 
it is not perceptibly dissolved in the caustic potash. 

An approximate separation of citrate and tartrate can be effected 
by means of this reaction. Both radicals are precipitated as cal- 
cium salts, and the rapidly washed precipitate is mixed with potas- 
sium hydroxide solution, diluted, and filtered ; the filtrate contains 
the tartrate, which is shown to be present by the reprecipitation 
on boiling. The precipitate still on the filter is washed, dissolved 
in solution of ammonium chloride, and the solution boiled; the 
calcium citrate is reprecipitated. The presence of much sugar 
interferes with this reaction. A dilute solution of a citrate is not 
precipitated by calcium chloride until the liquid is heated: precip- 
itation from a concentrated solution, also, is not complete Avith- 
out ebullition of the mixture. This reaction is not thoroughly 
satisfactory, calcium citrate being slightly soluble in alkalies, in 
the solutions of salts produced in the reaction, and, to a very 
slight extent, even in cold water. It is readily soluble in acetic 
acid. 

2, To a neutral solution of a citrate add solution of silver 
nitrate; a white precipitate of silver citrate, Ag.fififi^, is 
produced. Boil the mixture; the precipitate does not blacken 
rapidly as silver tartrate does, but only after long boiling. 



CITRATES. 811 

Other Analytical Reactions. — Citric acid I'uims nv piculpi- 
tate corresponding to potassium bitartrate. — Lime-water, in 
excess, gives no precipitate with a dilute solution of citric acid 
or of a citrate unless the solution is boiled, calcium citrate 
being slightly soluble in cold but not in hot water; lime-water 
usually gives precipitates with tartrates in the cold. — Citrates 
do not char immediately when heated with concentrated sul- 
phuric acid. — Citric acid and citrates prevent the precipitation 
of iron by alkalies, soluble double compounds being formed. 
The official Iron and Ammonium Citrate (Ferri et Aynmonii 
Citras, U. S. P.) is a preparation of this kind. — Metallic 
citrates decompose when heated, carbonates being formed and 
carbon set free; the odor of the gaseous products is not so 
characteristic as in the case of tartrates. — According to Cail- 
letet a cold saturated solution of potassium dichromate turns 
a solution of tartaric acid dark-brown, carbonic anhydride 
being evolved, while a solution of citric acid only slowly 
becomes light-brown. 

Fusch's tests for the detection of tartaric acid in citric acid depends 
on the well-known difference in the action of sulphuric acid on 
tartaric acid and on citric acid. It consists in adding to 1 
gramme of powdered citric acid in a dry test-tube 10 grammes of 
pure concentrated (colorless) sulphuric acid, and keeping the part 
of the tube containing the mixture immersed in boiling water for 
an hour. The citric acid dissolves with evolution of gas and 
frothing to form a lemon-colored liquid, and if the sample be pure 
this color undergoes no change within half an hour ; but if as 
much as one-half percent, of tartaric acid be present, the lemon 
color becomes brownish within that time, and in an hour the 
mixture is red-brown. 

The presence of tartaric acid may also be detected by the 
following method: — Add 1 gramme of citric acid to 1 Cc. of a 10 
percent, solution of ammonium molybdate, and then a few drops 
of a very dilute solution of hydrogen peroxide ; if tartaric acid is 
present, a fine blue color appears : in its absence the color is 
yellow. (Crismer. ) 



QUESTIONS AND EXERCISES. 

What is the source of citric acid ? — Describe the preparation of citric 
acid, giving equations. — Illustrate by formula?, the various classes of 
tartrates and citrates. — State the average proportion of citric acid in 
lemon-juice. — What are tbe tests for citrates? — How are tartrates sepa- 
rated from citrates ? 



,n2 THE ACID RADICALS. 

PHOSPHORIC ACID, H3PO,, AND OTHER PHOSPHATES. 

Source. — The source of the ordinary phosi3hates and of phos- 
phorus itself (PAos/?Aor«<s U. S. P.) is the normal calcium phos- 
phate, Ca3(POj2- This is the chief constituent of the bones and 
teeth of animals, being derived from the plants on which they 
feed, plants again obtaining it from the soil. Compounds of 
phosphorus are also met with in the brain, nerves, muscles, blood, 
saliva, and, according to Kirkes, even in tissues so simple that 
one must assume that the compounds are necessary constituents 
of the substance of the primary cell. Phosphates are eliminated 
from the system both in the urine and in the faeces. 

Phosphorus is obtained from bones by the following processes : 
— The bones are calcined to remove all traces of animal matter. 
The resulting bone-earth is treated with hot and moderately con- 
centrated sulphuric acid, whereby phosphoric acid and calcium 
sulphate are produced : — 

Ca3(POj2 + 3H,S0, = 2H3PO, + 3CaS0, 

The acid fluid strained from the calcium sulphate and concen- 
trated, is mixed with charcoal, coke, or sawdust and dried in an 
iron pot. At this stage water escapes, and metaphosphoric acid 
remains : — HgPO^ = HPO3 + HgO. The mixture is then trans- 
ferred to a fireclay retort and strongly heated ; phosphorus vapor 
is evolved and is condensed under water while hydrogen and 
carbonic oxide escape. 

4HPO3 + 12c = P^ 4- 2H2 + 12C0 

The phosphorus is purified by melting under water containing 
sulphuric acid and potassium dichromate, and is filtered through 
canvas and cast into sticks. 

Properties. — Phosphorus is a translucent, wax-like solid (in 
sticks or cakes), which emits white fumes, which are luminous in 
the dark, when exposed to the air. Sp. gr. 1.82. It is soft and 
flexible at common temperatures, melts at 111.2° F. (44° C.) ignites 
in the air at a temperature a little above its melting-point, burns 
with a luminous flame and produces dense white fumes. It is 
insoluble in water, but soluble in ether, in boiling oil of turpen- 
tine, in carbon bisulphide, absolute alcohol, and chloroform. It 
is soluble in oil which has been previously heated for a short 
time to about 300° F. (148.8° C), to expel moisture. Pills con- 
taining it are official. [Piluke Fhosphori, U. S. P. ) 

Granulated or pulverulent phosphorus is obtained by placing a 
quantity of phosphorus under equal parts of alcohol and water in 
a bottle, standing the bottle in warm water until the phosjjhorus 
melts, then inserting the stopper (glass, not cork), and shaking 
the whole till cold. 



PHOSPHATES. 313 

Red or ^ ^ Amorphous' ^ Phosphorus. — Ordinary phosphorus when 
kept at a temperature of about 450° F. (232.2° C.) in an atmos- 
phere from which air is excluded, becomes red, opaque, and in- 
soluble in liquids in which ordinary phosphorus is soluble. The 
red modification of phosphorus obtained in this way undergoes 
oxidation extremely slowly, and only ignites when heated to near 
500° F. (260° C). Though long regarded as amorphous and 
still known as amorphous phosphorus, its structure is really crys- 
talline. It is used in the manufacture of several varieties of 
matches, and it has the advantage of not emitting the poisonous 
fumes given off by ordinary phosphorus. 

Quantivalence. — Phosphorus is a quinquivalent element, as seen 
in the pentachloride, PCI., and oxychloride, POCl.^ ; but it often 
exhibits trivalent activity, as seen in the trichloride, PCI3, and 
trihydride, PH.^. 

Molecula formula. — The vapor density of phosphorus corre- 
sponds to the molecular formula, P^. Phosphorus in the state of 
vapor thus differs from oxygen, hydrogen, chlorine, etc., by 
having four atoms in its molecule, whilst these elements have 
only two. 

Phosphoric Acid. 

The chief use of phosphorus in pharmacy is for the pro- 
duction of Diluted Phosphoric Acid. Phosphorus is boiled 
with nitric acid and water until it disappears. The solution, 
evaporated to a small volume to remove nitrous compounds 
and until the product has a sp. gr. of 1,707, contains 85 per- 
cent, of phosphoric acid, HgPO^, and is the Acidum Phos- 
phoricum U. S. P. The latter, diluted so as to contain 10 
percent, of phosphoric acid constitutes the Acidum Phosphori- 
cum Dilutum, U. S. P., a colorless sour liquid of sp. gr. 1.057. 
If the necessary appliances are at hand, specimens may be 
prepared by boiling together 103 grains of phosphorus, 1} 
fluidounces of the official nitric acid, and 2 ounces of water 
in a flask attached to a vertical condenser (or some such 
arrangement whereby the condensed products are returned to 
the flask) until the phosphorus has disappeared, 

3P, + 20H]SrO3 + 8H,0 = 12H,P0, + 20NO 

Phosphorus Nitric acid Water Phosphoric acid Nitric oxide 

The liquid remaining in the flask is then transferred to a 
dish (preferably of platinum), evaporated down to about half 
an ounce, and then diluted with the necessary quantity of 
distilled water. 



314 THE ACID RADICALS. 

The use of tlie water in the earlier part of the process is to 
moderate the reaction. Hot concentrated nitric acid oxidizes 
phosphorus with almost explosive rapidity, hence the acid must be 
diluted in the first instance, and the dilution must be maintained 
to prevent the acid from becoming too concentrated by loss of 
water. Time is saved by using concentrated acid, but in that 
case constant supervision is necessary in order that water may be 
added, or the temperature otherwise reduced, should the action 
become too violent. Deficiency of nitric acid must also be 
avoided, or some phosphorous acid, H3PO3, will be formed. 

Markoe, also to economize time, modified the process by add- 
ing for every ounce of phosphorus 4 or 5 grains of iodine and, 
drop by drop, 25 or 30 drops of bromine. The iodine and 
bromine unite with the phosphorus readily, or even with violence 
that would be explosive if not controlled by the presence of the 
cold fluids (farther cooled, if necessary, by immersing the vessel 
in cold water). In the course of the reaction it may be assumed 
that phosphorus iodide and bromide are first formed. These in 
the presence of water immediately yield hydriodic and hydro- 
bromic acids (HI, HBr) and phosphoric acid. The nitric acid 
attacks the hydriodic and hydrobromic acids, yielding the lower 
oxides of nitrogen (which escape as gas), water, and free iodine 
and bromine. The latter unite with more phosphorus, and the 
reactions are repeated. This carrying power of a small quantity 
of iodine or bromine or both would perhaps be indefinitely pro- 
longed if no vapor of these elements or of hydriodic and hydro- 
bromic acids escaped with the gases. The phosphorus having 
disappeared, excess of nitric acid is mostly got rid of by dropping 
in clean rags or paper (nitric oxide, carbonic anhydride, and 
water being formed) and' the last portions, by adding oxalic acid 
(which even more readily yields similar products). Evaporation 
to a syrupy consistence finally removes all traces of iodine, bro- 
mine, oxalic acid, and moisture. The product is then diluted to 
any required extent. 

Experimental process. — A flask, into the neck of which a funnel 
is inserted, while a second funnel is inverted so that its mouth 
rests within the mouth of the first, is an efi&cient and convenient 
arrangement of heating and condensing apparatus for this pro- 
cess, especially if the operation be conducted slowly. {See Fig. 39.) 

Solution of phosphoric acid evaporated to a sp. gr., at 25.5° C, 
of 1.850 yields a mass of prismatic crystals, H^PO^, especially if 
a crystal or two of the acid from a previous preparation be dropped 
into the fluid (Cooper). Further evaporated, it leaves a residue 
which melts at a low red heat, y\e\dmg pyrophosphoric acid, H^Ffi^, 
and finally, mefaphosphoric acid, HPO3 {Glacial Phosphoric Acid). 
(Compare p. 333.) 

A commercial variety of phosphoric acid, containing no large 



PHOSPHATES. 



315 



Fig. 39. 



amount of impurity, is prepared by throughly digesting a mixture 
of bone-ash, sulphuric acid, and water; filtering, concentrating, 
precipitating calcium by means of concentrated sulphuric acid; 
and heating until sulphuric acid vapors no 
longer escape. It is also prepared by burn- 
ing phosphorus so as to obtain phosphoric 
anhydride, dissolving the latter in water, 
and boiling- with a little nitric acid to ox- 
idize any lower acids of phosphorus and to 
cause any meta- or pyro-phosphoric acid to 
take up the elements of water and form 
ordinary or orthophosphoric acid. 

Prepared from bones, phosphoric acid is 
apt to develop fungoid deposits (Jensen). 
Prepared from phosphorus, it occasionally 
contains arsenic in the form of arsenic acid. 
The latter is detected and removed, to- 
gether with any traces of platinum or lead, 
by passing hydrogen sulphide for some 
time through the warmed acid. 

Quantivalence. — The acid radical of the ordinary phosphates, or 
orihophosp hates, is trivalent (PO/^^). By the replacement of all 
or of a part of the replaceable hydrogen of orthophosphoric acid, 
H3PO4, trimetallic phosphates (M^gPO^), dimetallic acid phos- 
phates (M^^HPOJ, or monometallic acid phosphates (M^K^FO^), 
can be obtained. The phosphates met with in nature or used in 
pharmacy are all orthophosphates. 

Crude dry calcium phosphate ground with sulphuric acid yields 
the very largely used artificial manure termed ''superphosphate." 
It contains acid calcium phosphate, CaH4(POj2> 2H.^0, and cal- 
cium sulphate, CaSO^, 2H2O. 

The rarer pyrophosphates and metaphosphates, as well as the 
phosphites and hypophosphites, will be mentioned subsequently. 




Analytical Reactions of Orthophosphates. 

1. To an aqueous solution of a phosphate (e.g., Na.,HPOJ 
add solution of magnesium sulphate or chloride with which 
ammonium chloride and ammonia have been mixed (''mag- 
nesia mixture"); a white crystalline precipitate of ammonium 
magnesium phosphate, NH^MgPO^, is produced. 



Ammonium chloride is added to prevent the precipitation of 
magnesium hydroxide. Arsenates, which have close analogy with 
phosphates, give, with magnesia mixture, a precipitate of ana- 
logous composition. 



316 THE ACID RADICALS. 

2. To an aqueous solution of a phosphate add solution of 
silver nitrate ; light yellow silver phosphate, AgyPO^, is pre- 
cipitated — completely, if the mixture be neither acid nor alka- 
line. To a portion of the precipitate add ammonia water ; it 
dissolves. To another portion add nitric acid ; it dissolves. 
By the first part of this reaction phosphates may be dis- 
tinguished from their close allies, the arsenates, silver arsen- 
ate being brown. 

3. To a solution (in a few drops of acid) of a phosphate 
insoluble in water (^e.g., CagfPOJJ add an alkali-metal 
acetate (easily made by adding excess of acetic acid to sodium 
hydroxide or to ammonia water in a test-tube), and then a 
drop or two of solution of ferric chloride ; a yellowish white 
precipitate of ferric phosphate, FePO^, is produced, insoluble 
in acetic acid. Too much ferric chloride must not be added, 
or ferric acetate will be produced, in which the ferric phos- 
phate is to some extent soluble. 

To remove the ivhole of the phosphoric radical from the solu- 
tion add ferric chloride so long as a precipitate is produced, 
and boil ; ferric phosphate and oxyacetate are precipitated. 

To obtain confirmatory evidence of the presence of phosphate 
in this precipitate (and to separate the phosphoric radical as 
a phosphate of more characteristic appearance), collect the 
precipitate on a filter, wash, drop some ammonia water on it, 
then ammonium hydrosulphide, and finally wash with water; 
black ferrous sulphide remains on the filter, while ammonium 
phosphate is present in the filtrate. To the filtrate add mag- 
nesia mixture and stir well ; a granular precipitate of ammo- 
nium magnesium phosphate appears. 

4. Dissolve a little calcium phosphate (or any other phos- 
phate) in dilute nitric acid, add solution of ammonium molyb- 
date, ^ and heat gently ; yellow precipitate is produced. This 
precipitate contains what is somewhat indefinitely termed phos- 
pho-molybdic acid — a compound of molybdic acid and phos- 
phoric acid (about 4 percent, of HgPO^) with ammonia (nearly 
7 percent). 

^Molybdenum much resembles lead, hence the name of the metal, from 
jutoAviSSos, molubdos. lead. Ammonium molybdate. (XHi^oMoOi, is obtained 
by roasting the native molybdenum sulphide, M0S2. so as to convert it 
into molybdic oxide or anhydride, M0O3, mixing the latter with water, 
adding ammonia, evaporating and crystallizing. Molybdates having the 
formula M2M0O+; MHM0O4; MHM0O4, H2M0O4 (M=l univalent atom 
of any metal) have been obtained. Commercial ammonium molybdate 
is commonly the intermediate salt. 



PHOSPHATES. 317 

According to von Juptner tartaric acid, even in large excess, 
does not prevent the complete precipitation of phosphoric acid by 
molybdate solution. The addition of tartaric acid to the molyb- 
date solution or to the phosphate is therefore to be recommended, 
to prevent the contamination of the yellow precipitate with ferric 
compounds. 

Note. — The foregoing two reactions are useful in the analysis of 
bone-earth, of other earthy phosphates, iron phosphate, and all 
phosphates insoluble in water. Only arsenates give similar appear- 
ances ; but the acid solution of these may be decomposed by agita- 
tion with sulphurous acid, ebullition, and subsequent treatment 
with hydrogen sulphide — yellow arsenous sulphide, As.^Sg, being 
then precipitated. 

Other Analytical Reactions of Phosphates. — Solutions of 
barium and calcium salts give, with aqueous solutions of phos- 
phates, white precipitates ofthe respective phosphates, BaHPO^, 
or Bag (POJ2, and CaHPO,, or CagCPO,)^, all of which are 
soluble in acetic and the stronger acids. 



QUESTIONS AND EXERCISES. 

State the direct and indirect sources of phosphorus. — Give equations 
explanatory of the isolation of phosphorus from its compounds. — Enumer- 
ate the properties of phosphorus. — Mention some solvents of phosphorus. 
— How are the two chief varieties of phosphoric acid made ? Describe 
the precautions to be observed in making this acid.— What are the 

strengths of the ofla.cial acids? — Write formulae illustrative of all classes JJ(f| 

of orthophosphates. — What is the composition of farmers' "superphos- 
phate," and how is it prepared ? — Mention the chief test for soluble and 
insoluble phosphates. — By what reactions may phosphates be distinguished 
from arsenates? 



Vanadium V, 50.8, is a very rare element, and is here men- 
tioned only because of its exceedingly interesting relatiim- 
ship to nitrogen, phosphorus, arsenic, and antimony; along 
with which it forms a series of five closely allied elements. 
Discovered, but not isolated, by Sefstrom, and its compounds 
investigated by Berzelius, it was obtained in the free state and 
fully studied by Roscoe. 

The subjoined forraulse illustrate the resemblance in com- 
position between some of the compounds of vanadium and 
those of nitrogen and phosphorus : — 



m 



318 



THE ACID RADICALS. 



N,0„ N,0„ N,03, NO, N,0. V,0„ V,0„ Yfi,, VO, V,0. 



Orthophosphates . 
Pyrophosphates . 
Metaphosphates . 


R'3P0, Orthovanadates . ^\\0, 
^\^.0, Pyrovanadates . R',V 
RTO3 Metavanadates . R'VOg 




Isomorphous Minerals. 


Apatite 
Pyromorphite 
Mimetesite 
Vanadiuite 


. 3Ca3(POJ„ CaF, 
. 3Pb3(PO,)„ PbCl, 
. 3Pb3(AsOJ„ PbCl, 
. 3Pb3(V03),, PbCl, 



BORIC ACID, H3BO3, AND OTHER BORATES. 

The element boron, like carbon, occurs in the amorphous, graphi- 
toidal, and crystalline conditions. It is a trivalent element yield- 
ing halogen compounds, such as the chloride, BCL, and fluoride, 
BFg. Its atomic weight is 10. 9. 

The composition of crystallized boric acid (also called boracic 
acid), is expressed by the formula H3BO3 ; but at a temperature 
of 212° F. (100° C.) this compound loses the elements of water and 
yields metaboric acid, HBO2, which, by further loss of water at 
higher temperatures, becomes boric anhydride, BgOg. Metaboric 
acid exists in the jets of steam {fumaroles or suffioni) that issue from 
the earth in some districts of Tuscany, and it collects in the water of 
the lagoni (lagoons or little lakes) formed at the orifices of the steam 
channels. This acid liquid, evaporated by the aid of the waste 
natural steam, and neutralized by addition of sodium carbonate, 
yields borax. This salt is usually regarded as sodium tetraborate 
pyroborate, NajB^^, lOH^O, {Sodii Boras, U. S. P.), analogous 
in a sense to potassium dichromate, K2Cr20^. Native borax or thi- 
cal, and other borates, are also found in Thibet, Nevada, Peru, 
Chili, and, abundantly, in California in the Colorado district. 
Californian borax is represented as forming large portions of the 
crystalline bed of a dried-up lake. Borax is also made on a large 
scale by boiling native calcium borate with sodium carbonate. It 
is sometimes termed sodium biborate. It occurs in transparent 
colorless crystals, sometimes slightly efiioresced, or a white odor- 
less powder, with a weak alkaline reaction ; insoluble in alcohol 
(90 percent.), soluble in 25 times its weight of cold, and in half 
its weight of boiling water. 

Fused borax readily dissolves metallic oxides, as will have been 
noticed already in testing for cobalt and manganese (compare 
experiment 3, p. 140, and experiment 3, p. 142). Hence, besides 
its use in medicine, borax is employed as a flux in refining and 



BORATES. 319 

other metallurgic, and in ceramic, operations ; it is also an ingre- 
dient in starch glazes. Glyceritum Boroglycerini, U. S. P., is 
obtained by adding boric acid to glycerin heated to a temperature 
not exceeding 150° C. Borax honey formed of 2 parts of borax 
to 16 of honey, is a very old antiseptic for the mouths of infants 
troubled by the growth called ' 'thrush. ' ' 

Quatitivalence. — The acid radical of the borates is trivalent 
(BOg^^^) ; that of the metaborates univalent (BO/). 

Experiment 1. — To a hot concentrated solution of borax 
add a few drops of sulphuric acid and set aside ; on cooling, 
crystalline scales of boric acid, H^BOg (Acidum Boricum, 
U. S. P.), are obtained. The acid may be purified by collect- 
ing on a filter, slightly washing, drying, digesting in hot alco- 
hol, filtering, and setting aside ; pure boric acid is deposited. 
The acid may also be crystallized from water. 

Boric acid occurs in colorless, pearly, lamellar crystals or irregu- 
lar masses of crystals ; unctuous to the touch ; taste faintly bitter, 
leaving a sweetish after-flavor in the mouth. Soluble in 18 parts 
of water, in 4.6 of glycerin, in 15.3 of alcohol at 25° C, and in 3 
of boiling water. It changes the color of litmus to wine-red in the 
cold, a hot saturated solution giving a bright red color ; turmeric 
paper, moistened with an aqueous solution, even when slightly 
acidulated with hydrochloric acid, becomes brownish- red on gently 
drying, and this color changes to a greenish-black if solution of 
potassium hydroxide be added. The solution in alcohol burns 
with a flame tinged with green, especially when the solution is 
acidulated with sulphuric acid. Boric acid liquefies when warmed, 
and on careful heating loses 43.6 percent, of its weight, the pro- 
duct solidifying on cooling, m a brittle glass-like mass. 

Boric acid is a very weak acid and only slowly decomposes car- 
bonates : a solution of borax possesses a strongly alkaline reaction. 

Boric acid is extensively used as an antiseptic in the preserva- 
tion of foods, especially in the production of ' 'mild-cured' ' bacon 
and ham, etc. 

Experiment 2. — Mix together 1 part of boric acid, 4 parts 
of acid potassium tartrate, and 10 to 20 of water ; evaporate 
to a syrupy consistence, spread on plates and set aside for dry 
scales to form. The resulting substance is far more readily 
soluble in water than either of its constituents, and is known 
as potassium boro-tartrate, or soluble cream of tartar. The 
Prussian tartarus boraxatus differs from the foregoing Frencli 
variety in containing 1 part of bora.v to 8 of acid pota^^s'uin 
tartrate. 



320 THE ACID RADICALS. 

Analytical Reactions of Borates. 

1. Dip a piece of turmeric paper (paper soaked in tincture 
of turmeric tubers and dried) into a solution of boric acid ; it 
is colored brown-red, as by alkalies. 

The usual mode of applying this test is as follows : — Add to a 
solution of any borate a few drops of hydrochloric acid, immerse 
half of a slip of turmeric paper in the liquid, then dry the paper 
over a Bunsen flame to develop the brown color. (Concentrated 
hydrochloric acid or ferric chloride would produce a somewhat 
similar change of color. ) Place a drop of sodium hydroxide solu- 
tion on the browmed turmeric paper : a dark green color is pro- 
duced. 

2. To a fragment of a borate, pyroborate, or metaborate 
(borax may be used) in a small dish or watch-glass, add a 
drop of concentrated sulphuric acid and then a little alcohol ; 
warm the mixture and set fire to the alcohol ; the resulting 
flame is tinged green at its edges by the volatilized metaboric 
acid. 

The liquid should be well stirred while burning. Salts of cop- 
per and some metallic chlorides produce a somewhat similar color. 
The flame-test may also be applied to a small quantity of a mix- 
ture of the borate with sulj^huric acid on a platinum wire. Gly- 
cerin may be used instead of sulphuric acid (lies), the reaction 
with borax being, according to Dunstan, the formation of glyceryl 
borate, C3H5BO3, water, and sodium metaborate ; the glyceryl bor- 
ate and water interacting immediately to form boric acid and gly- 
cerin. If the borax and the glycerin are both anhydrous no boric 
acid is formed as the water resulting from the decomposition is 
immediately volatilized by the heat. 

Other Analytical Reactions. — In a moderately concentrated 
solution of borax, a barium salt produces a white precipitate 
of barium metaborate, Ba(B02)2, soluble in acids and certain 
salts. Silver nitrate also afforcls a white precipitate of silver 
metaborate, AgBOg, soluble in nitric acid and in ammonia. 
Calcium chloride, if the solution is not too dilute, gives a 
white precipitate of calcium metaborate, Ca(B02)2. 



QUESTIONS AND EXERCISES. 



Illustrate the relations of vanadkim to nitrogen and to phosphorus by 
formulfe of compounds of each element. — Describe the preparation of 
borax. — Give the formulae of boric acid metaboric acid, and borax. — Men- 
tion the tests for borates or metaborates. 



BENZOATES. 



321 



The foregoing acids and salts comprise those which are 
commonly employed in ordinary medical or pharmaceutical 
operations. There are, however, many others which are occasion- 
ally used. The chief of these will now he shortly noticed ; they 
are arranged in alphabetical order to facilitate reference. 



SALTS OF RARER ACID RADICALS. 

Benzoic Acid, HC^H^O^, and other Benzoates. — 

Slowly heat a fragment of benzoin (Gum Benjamin) {Benzo- 
inum, U. S. P.)^ ill a test-tube ; benzoic acid (Acidum Benzo- 
icum, U. S. P.) rises in vapor and condenses in small, white, 
feathery plates and needles on the cool sides of the tube. If 
the benzoin is first mixed with twice its weight of sand or 
roughly powdered pumice-stone, and the heat very cautiously 
applied the product will be less likely to be burnt, and a larger 
quantity will be yielded. By repeated sublimation 10 to 15 
percent, may be obtained. 

A more economical process is to boil the benzoin with one- 
fourth its weight of calcium hydroxide, filter, concentrate ; 
decompose the dissolved calcium benzoate by adding hydro- 
chloric acid ; collect the precipitated benzoic acid, press 
between filter-paper, dry, and sublime in a tube or other 
vessel. 



2HC,HA + Ca(OH), 

Benzoic acid Calcium 

(impure) hydroxide 



Ca(C,H,0,), + 2Ufi 



Calcium 
benzoate 



Water 



Ca(C,H,0,), 

Calcium 
benzoate 



2HC1 = CaCL + 2HaH,0, 



Hydrochloric 
acid 



Calcium 
chloride 



Benzoic acid 

(pure) 



There is always associated with the product a minute quantity 
of a mixture of volatile oils of agreeable odor, suggesting that of 
hay, and yielding, according to Jacobsen, methyl benzoate, 
guaiacol (methoxy catechol), catechol, acetylguaiacol, benzyl ben- 
zoate, benzophenone, and benzoylguaiacol. 

Benzoic acid is also prepared on a large scale artificially from 
naphthalene, one of the crystalline by-products in the distillation 
of coal for gas. The naphthalene is oxidized by nitric acid to 
naphthalic or phthalic acid : — 



CioHc 



, + 80 = 

Naphthalene Oxygen 



Phthalic acid 



^■ 



Oxalic acid 



1 Sumatra benzoin (excluding wood) is soluble in ether, and the dis- 
solved substance yields 0.01 percent, of ash. 
21 



322 THE ACID RADICALS. 

The phthalic acid is neutralized by adding lime, and the 
calcium phthalate is heated with calcium hydroxide for several 
hours in a covered vessel at a temperature of about 640° F. 
(337.8° C). Calcium benzoate and carbonate are formed, and 
benzoic acid is set free by the action of hydrochloric acid on the 
mixture. 



JCaCgHp, 


+ 


Ca(OH), = 


= QK^M,0,\ 


+ 


2CaC03 


Calcium 




Calcium" 


Calcium 




Calcium 


phthalate 




hydroxide 


benzoate 




carbonate 



The crystalline deposit formed when oil of bitter almonds 
(benzoic aldehyde or benzaldehyde) is exposed to the air is ben- 
zoic acid. 

2CeH5COH -f O2 = 2CeH,C00H or 2HC.H.O2 
Benzaldehyde Oxygen Benzoic acid 

Pure sublimed benzoic acid is also obtained from hippuric acid 
(p. 325). 

Jacobsen has prepared benzoic acid from benzotrichloride 
(trichloromethylbenzene, C^ H.CCI3, one of the trichlorotoluenes) 
by heating with glacial acetic acid and zinc chloride. This acid, 
if not very highly purified, may give a green color to the flame 
when heated on platinum wire with a little copper oxide. In 
artificial benzoic acid the fragrant volatile oil characteristic of the 
acid from benzoin is absent. 

Properties. — Benzoic acid is slightly soluble in cold water, 
more so in hot, and readily soluble in alcohol (90 percent.). 
It melts at 250.5° F. (121.4° C.) and boils at 462° F. 
(238.8° C), volatilizing with only a slight residue. Heated 
with lime it yields benzene. It dissolves in cold sulphuric 
acid without decomposition, and is deposited again on dilu- 
tion ; the traces of odoriferous and other substances present in 
the acid obtained from benzoin only slightly color the fluid, 
even on warming gently. 

OflBlcial benzoates. — To a little benzoic acid add a few 
drops of ammonia water or of sodium carbonate solution ; the 
acid readily dissolves, forming the corresponding benzoate 
(Ammonii benzoas, U. S. P., NH^C^H.O^, or Sodii Benzoas, 
U. S. P., NaC^H.O^). AYith ammonia water the reaction 
is : — 

HC^H.O, + NH, = NH^aH.O, 

Benzoic acid Ammonia Ammonium benzoate 

On evaporating the solution, which is kept slightly alkaline 
throughout the evaporation by the addition of ammonia. 



CACOBYLATES, ETC 323 

crystals of ammonium benzoate are deposited. Benzoic acid 
also interacts with other alkaline liquids, forming benzoates. 
Lithium Benzoate {Lithii Benzoas) is official. 

Test for benzoates.— To a solution of a benzoate add a 
drop or two of sulphuric or hydrochloric acid ; a white crys- 
talline precipitate of benzoic acid separates. To another 
portion of the solution, carefully made neutral if necessary, 
add a drop or two of neutral solution of ferric chloride ; a 
reddish precipitate of ferric benzoate results. 

Cacodylic Acid (CHg)2AsO.OH. — This is a crystalline acid 
which is formed on exposure to air of cacodyl oxide, (CH3)^As20 
(Cadet's fuming liquid), an exceedingly poisonous and evil-smell- 
ing liquid produced by heating a mixture of arsenous anhydride 
and potassium acetate. Sodium cacodylate, (CHy)2As02Na, SHgO, 
ferric cacodylate, [(CH3)2AsO,j3Fe, and some other salts are now 
used in medicine. 

A salt somewhat analogous to sodium cacodylate, corresponding 
to the acidCH3AsO(OH)2 (methyl-arsenic acid), and rei3resented 
by the formula CH3AsO(OISra)2, 5H2O, has been introduced into 
medicine under the name arrhenal. This salt has been called 
sodium methy arsenate, a name which is quite inappropriate as 
the salt is not an arsenate. 

Carminic Acid, Cj-H^gOj^. — This is the coloring principle 
(about 10 percent.) of the dried female cochineal insect, Coccus 
Cacti, {Coccus, U. S. P.). The carmine of trade, when unadul- 
terated [see P. J., 1859-60, p. 546) is carminic acid associated 
with 2 or 3 percent, of alumina and lime, or, occasionally, of tin 
oxide or albumen. It should be wholly soluble in ammomia 
water, giving a clear, rich purple liquid. Carmine with French 
chalk, or starch, constitutes face rouge or animal rouge. 

Merrick tests the relative value of several samples of cochineal 
or carmine by observing how much solution of potassium perman- 
ganate is required to change the color of a decoction to a faint 
pink. The silvery coating of cochineal is a wax, coccerin. 

Cetraeic Acid, H2C,gHi^0g, is the bitter principle of Iceland 
moss. In the lichen it is associated with much starch. A fatty 
acid, lichenstearic acid, is also present. 

CiNNAMic Acid, CgH^COOH, — Benzoic acid is distinguished 
from an allied acid, cinnamic acid (occurring in Balsams of Peru 
and Tolu, in Storax, and sometimes in Benzoin), by not yielding 
benzaldehyde, C^H^COH (oil of bitter almonds), when distilled 
with a mixture of potassium dichromate and sulphuric acid, or 
when triturated with half its weight of potassium permanganate. 
Old hard balsam of tolu yields cinnamic acid on boiling with lime 
and water and precipitating by the addition of hydrochloric acid. 
Jacobsen makes cinnamic acid artificially by the prolonged inter- 



324 THE ACID RADICALS. 

action of glacial acetic acid and benzodichloride in the presence 
of zinc chloride. 

Cyanic Acid, HCNO, and other Cyanates. — The reducing 
action of potassium cyanide, KCX (or ferrocyanide, K^FeCgXg) on 
many metallic oxides, is due to the readiness with which it takes 
up oxygen and forms cyanate, KCXO. 

Experiment. — Fuse a few grains of potassium cyanide in a 
small porcelain crucible and add powdered lead oxide ; a 
globule of metallic lead is at once formed, excess of the oxide 
converting the whole of the potassium cyanide into potassium 
cyanate :— KCN + PbO = KCNO -f Pb. 

Potassium cyanate, KCNO, or better, lead cyanate. Pb(CX0)2, 
treated with ammonium sulphate, yields ammonium cyanate, 
XH^CXO ; and solution of ammonium cyanate, when evaporated 
to dryness, leaves a residue of urea, 00X2^4; ^^^ most important 
constituent of urine, and the chief form in which the waste 
nitrogen is eliminated from the animal system. The process will 
be more fiilly described subsequently in connection with urea. 

Embelic Acid, HCgH^gOg, appears to be the active principle 
of the vermifuge fruit of Emhelia Ribes and Embelia Robusta — 
Warden. 

Formic Acid, HCHOo. The red ant {Foi^mica rufa) and 
several other insects, when irritated, eject a strongly acid, acrid 
liquid, which contains formic acid ; the acid is also contained in 
the leaves of the stinging-nettle. 

Preparation. — Formic acid may be prepared artificially by 
heating equal weights of oxalic acid and glvcerin to a tem- 
perature of from 212° to 220° F. (100° to 104.4° C.) for 
fifteen hours, and then distilling the mixture with a consider- 
able volume of water. The formic acid, mixed with water, 
slowly passes over, glycerin being regenerated. The dilute 
acid may be obtained in a concentrated form by neutralizing 
with lead carbonate, filtering, evaporating to a small volume, 
collecting the deposited crystalline lead formate, drying, 
decomposing in a current of dry hydrogen sulphide, at 212° F. 
(100° C), and rectifving the resulting syrupv acid from dry 
lead formate. It should be fluid at 48° F. (8.^9° C.) and boil 
at 212° F. (100° C). The following are the chief reactions :— 

C3H/OH)3 + H,C,0, = C3HpHC,0, + 2H3O 

Glycerin Oxalic acid Glyceryl hydroxyoxalate Water 

CgH.OHC.O, -L 2H,0 = C3H.(OH)3 + HCHO, + CO, 

Glyceryl Water Glycerin Formic Carbonic 

hydroxyoxalate acid anhydride 



FORMATES, ETC. 325 

Formic Acid may be instructively though not economically pre- 
pared by the oxidation of methyl alcohol (wood-spirit), just as 
acetic acid and valerianic acid are obtained from ethyl alcohol 
and amyl alcohol respectively — 

CH3OH -f 20 = HCOOH -h H,0 
Methyl alcohol Oxygen Formic acid Water 

Tests. — Formic acid does not char when heated alone or with 
sulphuric acid, but splits up into carbonic oxide and water. It 
is recognized by this property and by its reducing action on salts 
of gold, platinum, mercury, and silver. It is solid below 32° F. 
(0° C). 

Gallic Acid. — See Tannic Acid. 

Hemidesmic Acid. — The supposed active principle of hemi- 
desmus root. 

Hippumc Acid, HCgHgNOg, is a constituent of human urine 
(much increased on taking benzoic acid), but is prepared from 
the urine of the horse (hence the name, from 'iTZTvog, hippos, a 
horse), or better, from that of the cow. To such urine add a little 
milk of lime, boil for a few minutes, remove precipitated phosphates 
by filtration, drop in hydrochloric acid until the liquid, after well 
stirring, is exactly neutral to test-paper, concentrate to about one- 
eighth the original volume, and add excess of concentrated hydro- 
chloric acid; impure hippuric acid is deposited. From a solu- 
tion of the impure acid in hot water chlorine removes the color, 
and the liquid deposits crystals of pure hippuric acid on cooling. 

Tests. — To a solution of a hippurate add neutral solution of 
ferric chloride; a brown precipitate of ferric hippurate results. 
Soluble silver and mercurous salts give white precipitates. Heat 
hippuric acid in a test-tube; it chars, benzoic acid sublimes, and 
vapors of characteristic odor are evolved; they contain, among 
other products, hydrocyanic acid and a substance smelling some- 
what like Tonka bean. The crystalline form of hippuric acid is 
characteristic; it will be described in connection with the subject 
of urine. 



QUESTIONS AND EXEECISES. 

Give the preparation, composition, properties, and tests of benzoic acid, 
employing equations. — What is the nature of carmine ? — Name the bitter 
principle of Iceland "moss." — How is potassium cyanate prepared, how 
converted into an ammonium salt, and what are the relations of the 
latter to urea. — Give the formula of cyanic acid, ammonium cyanate. 
and urea. — What is the formula of formic acid? — Describe the artificial 
production of formic acid, — What is the relation of formic acid to wood- 
spirit ? — State the sources, characters, and tests of hippuric acid. 



Hydroferrocyanic Acid, H^FeCj.N^,, or H^Fe(CN),., axd 
OTHER Ferrocyanides. —The ferrocyanide of most interest is 



326 THE ACID RADICALS. 

Potassium Ferrocyanide, Potassium Ferrocyanidum, U. S. P., 
'yellow pmssiate of potash," K_^Fe(CN)g, SH^, the formation 
of which was alluded to in connection with hydrocyanic acid 
{see p. 266). It cannot be regarded as simply a double salt of 
potassium cyanide with ferrous cyanide (4KCN, Fe(CN)2), its 
chemical properties being entirely different from those of either 
of these substances ; moreover unlike potassium cyanide, it is not 
poisonous. Most of the reactions point to the conclusion that in 
it iron and cyanogen are intimately united to form the quadriva- 
lent radical appropriately termed ferrocyanogen (FeCgXg)^^^^ A 
solution of 10 grammes of potassium ferrocyanide in sufficient 
water to measure 100 Cc. is the official Potassium Ferrocyanide 
Test Solution. 

Tests — Many of the ferrocyauides are insoluble, and are 
therefore precipitated when solution of potassium ferrocyanide 
is added to the salts of the various metals. The precipitates 
produced in solutions of iron and of cupric salts, being of 
characteristic color, are adopted as tests for the presence of 
these metals or of ferrocyanogen, as the case may be. To a 
solution of potassium ferrocyanide add a ferric salt ; a dark 
blue precipitate of ferric ferrocyanide, Fe^— (FeCgKg)3"", 
Prussian blue, is produced. To another portion add solution 
of a cupric salt ; a reddish-brown precipitate of cupric ferro- 
cyanide, Cu2Fe(CN)g results. 

Note. — The ferrocyanogen in potassium feiTOcyanide is broken 
up when the salt is heated with sulphuric acid, carbonic oxide 
being evolved if the acid is concentrated (that is, ordinary oil of 
vitriol — H,,SO^ with 2 or 3 percent, of water), and hydrocyanic 
acid if dilute: — 

K.FeCgNg, SHp + SH^O + 8H,S0, = 4KHS0, + FeSO, 
+ 3(NH,)2SO,"+ 6C0 

2K,FeCgNg + eH^SO, = FeK^FeCgNg -f 6KHS0, 
+ 6HCN 

Hydroferricyanic Acid, HgFeCgNg, or H3Fe(CN)g, and 
OTHER Ferricyanides. — Pass chlorine slowly through a solu- 
tion of potassium ferrocyanide until the liquid, after frequent 
shaking, ceases to give a blue precipitate when a minute por- 
tion is taken out on the end of a glass rod and brought into 
contact with a drop of dilute solution of a ferric salt ; it now 
contains Potassium Ferricyanide K3Fe(CN)g, "red prussiate 
of potash," as it is called from the color of its crystals. Excess 



FLUORIDES, .327 

of chlorine must be carefully avoided, as cyanogen chloride 
and other compounds are then formed. Such a result does 
not ensue if bromine be used instead of chlorine, but this pro- 
cess is less economical. 

2K,Fe(CN), + Cl^ = 2KC1 + 2K3Fe(CN), 

N'ote. — The removal of one-fourth of the potassium from the 
ferrocyanide is here accompanied by the conversion of the quad- 
rivalent radical ferrocyanogen (FeCgN^)^^^^, into the radical /erri- 
cyanogen (FeCgNg)^^^, which is trivalent. Besides by the action 
of chlorine, the conversion of potassium ferrocyanide into ferri- 
cyanide can be effected by the action of one or other of a variety 
of oxidizing agents. 

Tests. — To a solution of potassium ferricyanide add solu- 
tion of ferrous sulphate ; a dark-blue precipitate is produced. 
This precipitate is ferrous ferricyanide (TurnbuU's blue), 
Fe3"(FeCA);"- 



2K3Fe(CN), + 3FeS0, 


= 3K,S0. + Fe,(FeCA). 


Potassium Ferrous 


Potassium TurnbuU's blue 


ferricyanide sulphate 


sulphate 



A solution of 1 part of potassium ferricyanide in about 10 of 
water forms the official Potassium Ferricyanide Test Solution. 

Hydrofluoric Acid, HF, and other Fluorides. — 
Hydrofluoric acid is chiefly used for etching glass. The 
operation, performed on the small scale, also constitutes the 
best test for fluorine, the acid radical of the fluorides. 

Experiment and Test. — Coat the convex side of a watch glass 
(preferably one made of hard glass) with a layer of beeswax, 
by first heating the glass and then rubbing the wax over it. 
When the wax is cold, write through it with the point of a 
pin (or other instrument which is not hard enough to scratch 
the glass) so as to lay bare some portions of glass. Place a 
few grains of powdered fluor-spar (calcium fluoride, CaF.^, the 
commonest natural fluoride) in a small lead basin (or platinum 
crucible), add a few drops of sulphuric acid, cover the basin 
with the prepared glass, waxed side downward, and very 
gently warm the bottom of the basin in a fume-cupboard in 
such a way as not to melt the wax. After a few minutes 
remove the glass, wash the waxed side by pouring water over 
it, scrape off* most of the wax, then warm the glass and wipe 
off'the remainder ; the glass will be found to be etched at the 
places that were laid bare by the removal of the wax. The 
hydrofluoric acid liberated by the action of sulphuric acid on 



328- THE ACID RADICALS. 

the fluor-spar has eaten into or etched (from the German 
cdzeii, to corrode) the glass. 

The calcium fluoride and sulphuric acid yield hydrofluoric acid, 
thus :— CaF2 -f H^SO^ = CaSO, + 2HF. The hydrofluoric acid 
gas and the silica of the glass then yield silicic and flurosilicic acids 
and water, thus : — 

12HF + SSiO^ = H.SiO, + SH^SiF^ -f 2H,0 

Hydrofluoric Silica Silicic Fluosilicic "Water 

acid acid acid 

The silica being removed from the glass, leaves furrows or etched 
portions. 

The aqueous solution of hydrofluoric acid, used by etchers, and 
commonly termed simply hydrofluoric acid, or ''fluoric" acid, is 
prepared in leaden stills and receivers, and kept in leaden or gutta- 
percha bottles. Hydrofluoric acid rapidly attacks any substance 
of which bottles and basins are usually made except lead and 
gutta-percha. It is also without action on platinum and fluor- 
spar. It quickly cauterizes the skin, producing a painful, slow- 
healing sore. A mixture of hydrofluoric acid and ammonium 
fluoride, known as "white acid," is also used for etching glass. 

Experiments by Meslans show that anhydrous hydrogen fluor- 
ide has no action on absolute alcohol below 266° F. (130° C). 
Above that temperature interaction takes place ; and at 410° to 
428° F. (210° to 220° C. ) about 33 percent, of the gas is esterified 
in three hours, and gaseous ethyl fluoride may be collected. 

Quantivahnce. — Fluorine, like chlorine, bromine, and iodine, 
is univalent (F^). 

Fluorine has been isolated by electrolyzing hydrofluoric acid. It 
is a greenish-yellow gas with an irritating odor. It combines 
with great readiness with all elements except oxygen. By cooling 
and compressing the gas, Moissan and Dewar have obtained fluo- 
rine as a pale-yellowish liquid. 

Hypophosphorous Acid, HgPO^ or HPH.O^^ and other 
Hypophosphites. — Boil together in a fume-cupboard, two or 
three grains of phosphorus, three or four grains of calcium 
hydroxide, and about a quarter of an ounce of water, until 
hydrogen phosphides are no longer evolved. The volatile 
products of the interaction are trihydrogen phosphide (or 
phosphuretted hydrogen), PH^, and a small quantity of the 
vapor of a liquid phosphide, P2H^. The vapor of the latter 
ignites spontaneously in contact with air, and imparts to the 
gaseous mixture the property of spontaneous inflammability. 
The calcium hydroxide must not be in great excess, or the 
hypophosphite produced by the interaction will be converted 



HYPOPHOSPHITES. 329 

into phosphate as fast as formed. The mixture, filtered, and 
excess of lime removed by means of carbonic anhydride, yields 
a solution of calcium hypophosphite, Ca(PH202)2 (Calcii 
Hypophosphis, U. S. P.). The salt may be obtained in crys- 
tals by evaporation and slow cooling. 

2P, + 6HP + 3Ca(0H), = 3Ca(PHA)2 + 2PH3 

Trihydrogen phosphide or phosphuretted hydrogen, PH^. — The 
above reaction is the one by which phosphuretted hydrogen is 
usually prepared. If the gas is to be collected, the phosphorus 
and water may first be boiled in a flask until ajet of spontaneously 
inflammable phosphorus vapor escapes with steam, from the end 
of the attached delivery-tube. Hot concentrated solution of potas- 
sium hydroxide or sodium hydroxide is next very gradually poured 
into the flask through a funnel-tube previously fitted into the cork, 
the liquid being kept boiling. Potassium or sodium hypophosphite 
is formed in solution, while phosphuretted hydrogen is evolved, and 
if the delivery-tube dip under water may be collected, or allowed to 
slowly pass up through the water, bubble by bubble, so as to burst 
into flame spontaneously and form vortex rings of white smoke 
which arise one after the other into the air and are characteristic 
of the experiment. A solid hydrogen phosphide, P4H2, is known. 

Sodium Hypophosphite, ISTaPHgOg, H2O {Sodii Hypophosphis, 
U. S. P. ) is made by the interaction of solutions of calcium hypo- 
phosphite and sodium carbonate, filtering and evaporating to dry- 
ness. CalPH^O^), + Na^COg = maFUfi^ + CaCOg. It is a 
white, granular, deliquescent substance. When heated, the water 
is first evolved, then hydrogen and hydrogen phosphide, and a 
mixture of sodium pyrophosphate and metaphosphate remains. 
5NaPH,02 = Na^P.O, + NaPOg + 2PH3 4 1U.^. (Rammelsberg. ) 

Hypophosphorous Acid, hydrogen hypophosphite {Aeidum Hypo- 
phosphorosum, U. S. P. ), may be prepared by decomposing the 
calcium salt by means of oxalic acid, or better, the barium salt 
by means of sulphuric acid. 

Aeidum Hypophosphorosum Dilutum is also oflicial. 

Ferri Hypophosphis, Fe(PH202)3, Mangani Hypophosphis, 
Mn (PH202)2, and Fotassii Hypophosphis, KPH2O2, are included 
in the Pharmacopoeia. 

Quinine hypophosphite, is prepared by dissolving quinine in 
hypophosphorous acid, or by decomposing quinine sulphate by 
means of barium hypophosphite. The latter is obtained on boil- 
ing excess of pure barium hydroxide with ammonium hypophos- 
phite until all the ammonia has been evolved. The ammonium 
salt is formed on bringing calcium hypophosphite and ammonium 
oxalate together in presence of a little ammonia. 

The hypophosphites are often used in medicine in the form of 
syrups {Syrupus Hypophospkitum, U. S. P. ; Syrupus Hypophos- 



330 THE ACID RADICALS, 

phitum Composifus, U. S. P.). The term hypophosi)hite is used in 
connection with these salts on account of their containing a smaller 
proportion [vTrd, hupo, under) of oxygen than the phosphites (a 
class of salts which, in turn, contain less oxygen than the phos- 
phates). The prefix hypo has similar significance in such words 
as hyposulphite and hypochlorite. 

Tests. — To a solution of calcium or sodium hypophosphite 
add solution of barium chloride, calcium chloride, or lead 
acetate ; in neither case is a precipitate obtained, whereas 
soluble phosphates and phosphites yield white precipitates 
(of barium, calcium, or lead phosphate or phosphite). To 
other portions of a hypophosphite solution add solutions of 
silver nitrate and mercuric chloride ; precipitates of metallic 
silver in the one case and of mercurous chloride and then 
of metallic mercury in the other are produced. (Similar 
reactions are produced by phosphites.) To another small 
portion add zinc and dilute sulphuric acid ; hydrogen and 
hydrogen phosphide are evolved (as from phosphites). To a 
solution of calcium hypophosphite add sufficient oxalic acid to 
remove the calcium ; filter; to the solution of hypophosphorous 
acid so obtained add solution of cupric sulphate and slowly 
warm the mixture ; a brown precipitate of cuprous hydride, 
Cu^H,, is produced : heat to the boiling-point ; hydrogen is 
evolved and metallic copper is set free. Add a solution of a 
hypophosphite to a mixture of aqueous solution of ammonium 
molybdate with solution of sulphurous acid ; a blue precipi- 
tate results, or in dilute solutions, a blue color which deepens 
on standing. Heat a small quantity of a solid hypophosphite 
on the end of a spatula in a flame, and note the odor of phos- 
phuretted hydrogen and the combustion of this gas. The salt 
breaks up into pyrophosphate, some metaphosphate, hydrogen, 
hydrogen phosphide, and water, the oflScial calcium hypophos- 
phite yielding about 80 percent, of residue. 

7Ca(PH,0,), =3CXP,0, +Ca(P03), + 6PH3 -f H,0 + 4H, 

Five grains of calcium hypophosphite, if of good quality, 
will almost decolorize a solution of not less than twelve grains 
of potassium permanganate, on boiling the mixture for about 
ten minutes. Five grains of sodium hypophosphite should 
almost decolorize not less than eleven and a half grains of 
permanganate under similar conditions. 



LACTATES. 331 

Potassium permanganate, in acid solution, is also reduced 
by the solution of a phosphite but not by that of an ortho-, 
meta-, or pyro-phosphate. 



QUESTIONS AND EXEECISES. 



Give the formula of potassium ferrocyauide. — Enumerate the tests for 
ferrocyanogen. — What are the respective reactions of potassium ferro- 
cyauide with coucentrated and dilute sulphuric acid ? — Write equations 
illustrative of the changes eflFected in potassium ferrocyauide during its 
conversion into ferricyanide, — By what reactions may the presence of a 
ferricyanide in a solution be demonstrated ? — State the difference between 
Prussian blue and Turnbull's blue.— Describe thesource, mode of prepara- 
tion, chief use of, and test for hydrofluoric acid. — What compounds are 
produced by boiling phosphorus in solution of alkalies? — Give equations. 
— How is trihydrogen phosphide prepared ? 



Lactic Acid, HCgHgOg, and other Lactates. — Lactic 
acid occurs in willow bark (Dott). When milk turns sour, 
some of its sugar has become converted by the bacillus acidi 
lactici, fed by the nitrogenous matter, into lactic acid (lac, 
lactis). Other saccharine and amylaceous substances also 
yield lactic acid by fermentation. Neither hydrogen lactate 
(lactic acid) nor other lactates are much used in Great Britain. 

Preparation. — Calcium lactate and lactic acid may be 
prepared as follows : — Mix together eight parts of sugar, one 
of cheese, three of chalk, and fifty of water, and set aside in 
a warm place (about 80° F.) for two or three weeks ; a mass 
of small crystals of calcium lactate results. Remove these, 
recrystallize from hot water, decompose by means of sulphuric 
acid (avoiding excess), digest in alcohol, filter off* the calcium 
sulphate, evaporate the clear solution to a syrup ; this residue 
is ordinary lactic acid (Acidmn Lacticum, U. S. P.), sp. gr. 
1.206. 

A syrup of calcium lactophosphate is official {Si/nipus Calcii 
Lactophosphatis, U. S. P.). 

Test. — No single reaction of lactic acid is sufficiently distinctive 
to be regarded as a test. The crystalline form of calcium lactate, 
as seen under the microscope, is characteristic. The production 
of this salt, and the isolation of the syrupy acid itself, are the only 
means of identification, short of quantitative analysis, on Avhioh 
reliance can be placed. Lactic acid is soluble in water, alcohol, 



332 THE ACID RADICALS. 

and ether, but almost insoluble in chloroform. It is only slightly 
colored by cold sulphuric acid. Warmed with potassium perman- 
ganate, it gives the odor of aldehyde. 

A variety of lactic acid has been obtained from the juice of flesh ; 
it is termed sarcolactic acid (from oap^, oapKo-, sarx, sarcos, flesh). 
Unlike lactic acid, it yields a precipitate with solution of cupric 
sulphate. 

Malic Acid, C^HgO,, and other Malaxes (from malum, an 
apple). — Thejuices of unripe apples, gooseberries, currants, straw- 
berries, grapes, and of rhubarb-stalks, etc., contain malic acid 
and potassium malate. When isolated, malic acid forms deliques- 
cent prismatic crystals. 

Tests. — Calcium malate, CaC^H^Oj, is soluble in water, hence the 
aqueous solution of malic acid or other malate is not precipitated 
by lime-water or calcium chloride ; but, on adding alcohol, a white 
precipitate is produced, owing to the insolubility of calcium mal- 
ate in that liquid. Malates are precipitated by lead salts ; on 
warming the precipitate of lead malate with acetic acid it dissolves, 
separating out in acicular crystals on cooling. If the mixture be 
heated in absence of the acid, the precipitate agglutinates and fuses. 
Hot concentrated sulphuric acid chars malic acid far less readily 
than it does nearly all other organic acids. 

Asparagin (C^HgiS'203, HgO). — This proximate principle of plants 
occurs in many vegetable juices, and doubtless plays a very impor- 
tant part in their nutrition. It is deposited in crystals when the 
fresh juices of asparagus, marsh-mallow, etc., are rapidly evapor- 
ated. It is noticed here because malic acid is readily obtained 
from it by oxidation, nitrogen being eliminated. When its solu- 
tion is long boiled it is converted into ammonium aspartate, 
NH^C^HpNO^. Decomposed by aid of ferments, asparagin, absorb- 
ing hydrogen, yields ammonium succinate, (XH^)2C^H^0^. 

Meconic Acid, H^C.H^O., SH^O.— Opium contains mecouic 
acid (from /irjy.wv, mekdn, a poppy) partially combined with 
morphine. To concentrated infusion of opium, nearly neutral- 
ized with ammonia, add solution of calcium chloride ; crude 
calcium meconate is precipitated. Wash the precipitate, place 
it in a small quantity of hot water ; add a little hydrochloric 
acid; the clear liquid (filtered, if necessary) deposits scales of 
impure meconic acid on cooling. 

Tests. — To a solution of meconic acid or other meconate (or 
to infusion of opium) add a neutral solution of ferric chloride ; 
a red solution of ferric meconate is produced. To a portion 
of the mixture add solution of corrosive sublimate ; the red 
color is not destroyed : to another portion add hydrochloric 
acid ; the color is discharged. (These reagents act on ferric 



METAPHOSPHATES. 333 

thiocyanate, which is of similar tint, with exactly the opposite 
results. ) To another portion add a drop of a dilute acid, and 
boil ; the color is not discharged. (A solution of ferric ace- 
tate, which is of similar color, is decomposed on boiling, giving 
a colorless fluid and a red precipitate — ferric oxyacetate.) 

The normal potassium, sodium, and ammonium meconates are 
soluble in water, the acid meconates very slightly soluble ; the bar- 
ium, calcium, lead, copper, and silver meconates are insoluble in 
water, but soluble in acetic acid. 

Metaphosphoric Acid, HPO^ and other Metaphos- 
PHATES. — Prepare phosphoric anhydride, PgOg, by burning a 
small piece of phosphorus in a porcelain crucible placed on a 
plate and covered by an inverted test-glass, large beaker, or 
some such vessel. After waiting a few minutes for the phos- 
phoric anhydride to fall, pour a little water on the plate and 
filter the liquid ; the product is a solution of metaphosphoric 
acid : Pp, -f HP = 2HPO3. 

Tests. — To a solution of metaphosphoric acid add silver 
ammonio-nitrate, or to a neutral metaphosphate add solution 
of silver nitrate ; a white precipitate of silver metaphosphate, 
AgPOg, is obtained. This reaction sufliciently distinguishes 
metaphosphates from the ordinary phosphates or orthophos- 
phates (from 6pd6^^ orthos, straight), as the common phosphates 
may, for distinction, be termed (which give, it will be remem- 
bered, a yellow precipitate with silver nitrate): Another set 
of salts shortly to be considered, the pyrophosphates, also give 
a white precipitate with silver nitrate. (To the solution of 
metaphosphoric acid obtained as above or by the action of 
acetic acid on a metaphosphate, add an aqueous solution of 
white of egg ; coagulation of the albumen ensues. Neither 
orthophosphoric nor pyrophosphoric acid coagulates albumen. 
Boil the aqueous solution of metaphosphoric acid for some 
time ; on testing the solution, the acid will be found to have 
been converted into orthophosphoric acid : — 

HPO3 + H^ = H3PO, (orthophosphoric acid). 

The ordinary medicinal phosphoric acid is made from phos- 
phorus and nitric acid, the liquid being evaporated to a syru})y 
consistence (or treated as described on p. 315) to remove the Inst 
traces of nitric acid. It may contain pyrophosphoric and meta- 
phosphoric acids if the temperature employed be high enough to 
remove the elements of water : — 



334 THE ACID RADICALS. 

2H3PO,-H20 = H.Pp, (pyropliosphoric acid). 
H3PO4-H2O = HPO3 (metaphosphoric acid). 
On redilution the metaphosphoric acid only slowly reabsorbs 
water. If, therefore, on testing the diluted solution metaphos- 
phoric acid be found to be present, the solution should be boiled 
until conversion into orthophosphoric acid is complete. 

Nitrous Acid, HNOg, and other Nitrites. — Strongly 
heat a fragment of potassium or sodium nitrate on a piece of 
platinum foil ; oxygen is evolved, and impure potassium or 
sodium nitrate remains. 

Tests. — Dissolve the residue in water, add a few drops of 
dilute sulphuric acid, then some dilute solution of potassium 
iodide, and, lastly, some starch mucilage ; the deep-blue "starch 
iodide" is produced. 2HI + 2HN0, = 2Hp + 2N0 -f- I,. 
Repeat this experiment, using potassium nitrate instead of 
nitrite ; no blue color is produced. To a solution of a nitrite 
add solution of ferrous sulphate ; a brown coloration is pro- 
duced. Dissolve a small quantity of a nitrite in concentrated 
sulphuric acid, and add a few particles of cuprous oxide ; an 
intense violet purple color is produced. 

Tests for Nitrites in Water. — The liberation of iodine from potas- 
sium iodide in acid solution by nitrites and not by nitrates is a 
reaction of considerable value in searching for nitrites in ordinary 
drinking waters, the occurrence of such salts, except in very deep- 
seated springs being held to indicate the presence of nitrogenous 
organic matter in a state of oxidation or decay. The sulphuric 
acid used in the operation must be pure, and the potassium iodide 
free from iodate. If much organic matter is present, however, 
the nitric acid liberated by the sulphuric acid may be reduced 
to nitrous acid. It is perhaps best, therefore, to add acetic acid, 
and distil over 10 or 20 percent, of the water, and apply the test 
to this distillate (Fresenius). Very dilute solutions of nitrous acid 
may thus be distilled without the slightest decomposition. 

Sodium Nitrite, NaN02 {Sodii Nitris, U. S. P.). This salt 
yields ruddy nitrous fumes on the addition of sulphuric acid. 
When dissolved in water and tested in a nitrometer, with potas- 
sium iodide and dilute sulphuric acid, it should liberate a quan- 
tity of nitric oxide, corresponding to not less than 90 percent, of 
sodium nitrite. 

Other nitrates used in medicine are nitrites of organic radicals. 
Ethyl nitrite, C^H.NOj, or nitrous ether, is the most important 
constituent of Spiritus ^theris Nitrosi, V. S. P. Amyl nitrite, 
C. H^^NO,, is also otlicial [Amylis Nitris, U. S. P.). 

Ammonium nitrite, on being heated, yields pure nitrogen : — 



PHOSPHOROUS ACID. 335 

Determination of nitrous acid in commercial sulphuric acid 
(Lunge and SwoflPs method). 1 Cc. of Griess's reagent is put 
into each of a pair of Nesslerizing tubes and mixed with 40 Cc. 
of water and 5 grammes of sodium acetate. To the contents of 
the first tube 1 Cc. of the suspected acid is added, and to the 
other, without delay, 1 Cc. of a standard nitrite solution prepared 
by dissolving 0.0493 gramme of pure sodium nitrite in 100 Cc. of 
water and diluting 10 Cc. of this to 100 Cc. with pure sulphuric 
acid. The reddish colors may be compared after any convenient 
time, but it is best to wait five minutes. Griess' s reagent may be 
prepared as follows : — 0. 1 gramme of white a-naphthylamine is 
boiled for fifteen minutes with 100 Cc. of water and mixed with 
5 Cc. of glacial acetic acid. The solution is then mixed with 1 
gramme of sulphanilic acid dissolved in 100 Cc. of water, and the 
mixture preserved in a well-corked bottle. If it should become 
too red, it may be decolorized by shaking it with zinc dust. 

Note. — a-Naphthylamine, Cj^H^NHg, is obtained when a-naph- 
thol is heated for some time either with saturated aqueous ammo- 
nia, or with ammonium chloride and caustic alkali under pressure, 
or by the reduction of nitro-naphthalene. Sulphanilic acid, 
CgH^, SO3H.NH2, is prepared by heating a mixture of aniline and 
sulphuric acid containing some pyrosulphuric acid to a tempera- 
ture of 180° C. for several hours, and pouring into water, when 
the acid is precipitated in a crystalline form. 

Ophelic Acid, C^^^Jd^^. — This is one of the principles to 
which the herb Swertia chirayita, or Chiretta ( Chirata, 
U. S. P.), owes its bitterness. It is an amorphous yellow 
substance. Another is Chiratin, C^^'H.^fi-^^, decomposable by 
hydrochloric acid into Chiratogenin, C^fi^fi.^, and ophelic 
acid (Hohn). 

Phosphorous -Acid, H3PO3 or H^PHO.^. — A solution con- 
taining this acid in small quantity could be obtained by 
permitting the heavy white fumes which fall from a stick of 
moist phosphorus on exposure to the air to dissolve in some 
water placed at the bottom of a wide-mouthed bottle. Or 
phosphorous oxide, P^Og, may first be obtained by gently 
heating phosphorus in a tube, through which a slow current 
of air is drawn, condensing the fumes in a U-tube surrounded 
by a freezing mixture, and then decomposing the oxide by 
the action of water :— P,Og + 6Hp = 4H3PO,. Or chlor- 
ine is passed through phosphorus melted under water : — 
PCI3 + 3H.p == H3PO3 -f 3HC1. Having collected some 
phosphorous acid, apply the various tests already alluded to 
under Hypophosphoroiis Acid, first carefully neutralizing the 
phosphorous acid with a caustic alkali. 



336 THE ACID RADICALS. 

The soluble phosphites are prepared by neutralizing phos- 
phorous acid with the appropriate alkalies, and the insoluble 
phosphites by double decomposition. 

Associated with phosphorous acid prepared as above stated 
there is said to be an acid of the formula H2PO3, termed hypophos- 
phoric acid. 

Pyrogallic Acid. — See Tannic Acid. 

Pyrophosphoric Acid, H^P20^, and other Pyrophos- 
phates. — Heat ordinary sodium phosphate, Na2HP0^, 
I2H2O, in a crucible ; water of crystallization is first evolved, 
and anhydrous phosphate, Na^HPO^, remains. Further heat 
to redness ; water is again evolved and a new salt is obtained : 
— 2Na2HPO, =: H^O + Na.P^O,. The latter is termed 
sodium pyrophosphate, in allusion to its origin (ttD/?, pur, 
fire). From its solution in water it may be obtained in 
prismatic crystals, Na^P^O^, lOH^O. Phosphoric acid itself 
is similarly affected by heat, yielding pyrophosphoric acid : — 
2H3PO^ =: H2O 4- 11^1*2^7' though metaphosphoric acid is 
also formed. Other pyrophosphates are produced similarly, 
or by double decomposition and precipitation, or by neutraliz- 
ing pyrophosphoric acid with an oxide, hydroxide, or carbon- 
ate. Ferri Pyrophosphas Solubilis, and Sodii Pyrophosphas, 
Na.P^O,, IOH2O, are official. 

Tests. — To a solution of a pyrophosphate add solution of 
silver nitrate ; a dense white precipitate of silver pyrophos- 
phate, Ag^P20^, is produced, differing much in appearance 
from the white gelatinous silver metaphosphate or the yellow 
orthophosphate. To pyrophosphoric acid, or to a pyrophos- 
phate mixed with acetic acid, add an aqueous solution of 
albumen (white of egg) ; no precipitate is formed. Metaphos- 
phoric acid, it will be remembered, gives a white precipitate 
with albumen. Both pyro- and meta-phosphoric acids give 
precipitates on adding Tincture of Ferric Chloride. 

ACIDS OF PHOSPHORUS. 

The following acids of phosphorus have now been 
described : — 

Orthophosphoric acid, H^PO^ 
Pyrophosphoric acid, H^PgO^ 
Metaphosphoric acid, HPO^ 
Phosphorous acid,, H3P6 
Hypophosphorous acid, HgPOj 



SILICATES. 337 

The three phosphoric acids (ortho-, pyro-, and meta-) corre- 
spond to the higher oxide of phosphorus, PgO^, while phosphor- 
ous acid corresponds to the lower oxide, P^Og. Pyrophosphoric 
and metaphosphoric acids may be obtained from the ordinary or 
orthophosphoric acid by the removal of water. Hypophosphorous 
acid corresponds to a still lower (hypothetical) oxide of phos- 
phorus than P^Og. Although three hydrogen atoms are repre- 
sented in the formulae of both phosphorous and hypophosphorous 
acids, the acids behave as dibasic and as monobasic respectively. 



QUESTIONS AND EXEECISES. 
What are the sources of lactic acid ? — How is lactic acid usually pre- 
pared? — Name some of the plants in which malic acid is found. — Whence 
is meconic acid derived? — By what process may meconic acid be isolated? 
— Which is the best test for the meconic radical? — How may meconates 
be distinguished from thiocyanates ? — By what ready method may meta- 
phosphoric acid be obtained for experimental purposes ? — Name the tests 
for metaphosphates. — How may meta- or pyrophosphoric acid be con- 
verted into orthophosphoric acid ? — Describe the preparation of phosphor- 
ous acid. — How are the pyrophosphates prepared? — Give formulae 
illustrative of metaphosphates, pyrophosphates, orthophosphates, phos- 
phites, and hypophosphites. — Mention the tests by which meta-, pyro-, 
and orthophosphates are analytically distinguished. — How are hypo- 
phosphates and phosphites detected ? 



Silicic Acid, H^SiO^, and other Silicates. — Silicates of 
various kinds are among the commonest of minerals. The 
various days are more or less impure aluminium silicates ; the 
volcanic substance termed pumice-stone is a porous aluminium, 
alkali-metal, and alkaline-earth-metal silicate ; the varieties of 
felspar as a rule contain aluminium and alkali-metal silicates or 
aluminium and alkaline-earth-metal silicates ; meerschaum is an 
acid magnesium silicate ; the ordinary sandstones are chiefly silica ; 
sand., flint, quartz, agate, chalcedony, and opal are silicic anhydride 
or silica, SiOg. Tripoli powder, a polishing powder now found in 
many other countries than Tripoli, and consisting of infusorial 
skeletons, is nearly pure silica. Bath brick is a silico-calcareous 
deposit found in the estuary at Bridgwater, England, and other 
places. Tourmalines, plates of which, cut parallel to the axis of 
a crystal, are used as polarizers or analyzers in microscopy, are all 
aluminium silicates with varying proportions of iron, copper, 
manganese, or other silicates. Asbestos or amianth is a fibrous 
calcium and magnesium silicate, the length of the fibres varying 
from less than one inch to five feet. A single silk-like fibre can 
easily be fused, but even in very small mas'^es, asbestos is infusible 
in the Bunsen flame, and is incombustible. It is also a bad con- 
ductor of heat. It is largely used in packing piston rods and 
22 



338 THE ACID RADICALS. 

joints, and for steam apparatus generally ; as a covering for boilers 
to, prevent loss of heat by radiation ; and for so lining ceilings, 
floors, and other partitions as to render rooms, etc., fireproof. 
Artificial acid insoluble silicates are familiar in the form of glass 
and earthenware. Common window-glass (crown glass) is usually 
calcium, sodium, and aluminium silicate ; French glass, calcium 
and sodium silicate ; Bohemian glass, chiefly potassium and 
calcium silicate ; flint or crystal-glass for ornamental, table, and 
optical purposes, is mainly potassium and lead silicate. Earthen- 
ware is mostly aluminium silicate (clay), with more or less of the 
easily fusible silicates, namely, those of calcium, sodium, and 
potassium, and in the commoner forms, iron silicate. The 
various kinds of porcelain (China, Sevres, Meissen, Berlin, 
English), Wedgwood-ivare, and stoneware are varieties of earthen- 
ware. Kaolin, or China clay, which is disintegrated felspar, is 
the clay which yields the finest translucent porcelain. When 
powdered and freed from gritty particles by elutriation, it is 
official {Kaolinum, IT. S. P.). Crucibles, bricks, and tiles are 
made from different varieties of clay. Fireclay contains excess of 
silica and very small proportions of the fusible silicates, hence its 
refractory character. Mortar, if old, contains a little calcium 
silicate, but its binding action is due to the soft slaked lime 
penetrating the minute cavities on the surfaces of adjacent bricks 
and stones, and then becoming converted into an interlacing or 
''keying" mass of hard particles of calcium carbonate. The 
admixed sand which mortar contains, renders the mass porous and 
so far promotes absorption of carbonic anhydride from the atmos- 
phere, but its proportion should not much exceed two measures 
to one measure of lime, or, by weight, three of sand to one of 
good lime. Portland, R-oman, and other "hydraulic" cements are 
calcium silicates with more or less aluminium silicate. Fuller's 
earth {fullones, cleansers of cloth) is chiefly silica, but contains 
combined calcium, magnesium, aluminium, and iron, with a 
small quantity of potassium. Like the Arab's tfol, another earth 
containing gelatinous silica. Fuller' s earth is a powerful absorbent 
of oils and fats. 

Experiment. — Mix a few grains of powdered flint or sand 
with about five or six times its weight of sodium carbonate 
and an equal quantity of potassium carbonate, and fuse a 
little of the mixture on platinum foil in the blow-pipe flame ; 
the product is a soluble alkali-metal silicate, a soluble glass or 
water glass. Boil the foil in water, for a few minutes ; filter ; 
to a portion of the filtrate add excess of hydrochloric acid, 
evaporate the solution to dryness, and again boil the residue 
in dilute acid ; silicon oxide, silicic anhydride, or silica, SiOg, 
remains as a light, flaky, insoluble powder. 



SILICATES, 339 

The foregoing operation constitutes the test for silicates. By 
fiision with alkali the silicate is decomposed, and a soluble alkali- 
metal silicate formed. On addition of acid, silicic acid, H^SiO^, 
is set free, but remains dissolved if the solution is not too concen- 
trated. The heat subsequently applied eliminates water and con- 
verts the silicic acid into silica, SiOg, which is insoluble in water 
or hydrochloric acid. 

The soluble glass, water glass, or glass liquor of trade may be 
prepared by fusion, as above ; or by boiling up infusorial earth 
with solution of sodium hydroxide in closed vessels under a pres- 
sure of 7 or 8 atmospheres (the proportions of sodium hydroxide, 
silica, and water in the latter case being about 1, 2, and 5 respect- 
ively). 

By the addition of hydrochloric acid to soluble glass, and the 
removal of the resulting alkali-metal chloride and excess of hydro- 
chloric acid by dialysis (a process to be subsequently described), a 
pure aqueous solution of silicic acid may be obtained ; it readily 
changes into a gelatinous mass of silicic acid. Possibly some of 
the natural crystallized varieties of silica may have been obtained 
from the silicic acid contained in such an aqueous solution, nearly 
all natural waters yielding a small quantity of silica when evapo- 
rated to dryness with hydrochloric acid. 

A variety of silicic acid, HgSiOg, sometimes termed dibasic to 
distinguish it from the tetrabasic acid, H^SiO^, results when the 
aqueous solution of the latter is evaporated in vacuo. Various 
natural silicates correspond to this acid. 

Silicon hydride, or siliciuretted hydrogen, SiH^, is a spontaneously 
inflammable gas formed on treating magnesium silicide with hydro- 
chloric acid. It is the analogue of marsh gas or methane, CH^. 
A liquid silicon chloride, SiCl^, analogous to carbon tetrachloride, 
CCl^, and a gaseous fluoride, SiF^ are also known. The latter is 
formed when sulphuric acid acts on a mixture of a fluoride with 
silica or a silicate. It interacts with water with the production of 
silicic and fluosilicic acids (see p. 328). A carbon silicide, CSi, 
known as carborundum, is formed when carbon and silicon are 
heated together in an electric farnace. 

Many other analogies are traceable between the elements silicon 
and carbon, especially among their organic compounds. 

Succinic Acid, H^C Jip^. —Amber {Succinum) is a resin usually 
occurring in association with coal and lignite. From the fact that 
fragments of coniferous fruit are frequently found in amber, and 
impressions of bark on its surface, it is considered to have been 
an exudation from a species of Pinus now probably extinct. Heated 
in a retort, amber yields, first, a sour aqueous liquid containing 
acetic acid and succinic acid ; secondly, a volatile liquid known as 
oil of amber, resembling the oil yielded by most resinous substances 
under similar circumstances ; and, thirdly, a pitchy residue allied 
to asphalt. The succinic acid is a normal constituent of the amber, 



340 THE ACID RADICALS, 

the acetic acid is produced during distillation. Succinic acid has 
also been found in wormwood, in several jDine-resins, and in certain 
animal fluids, such as those of hydatid cysts and hydrocele. It is 
a product of the vital activity of various micro-organisms, and can 
be formed by these from carbohydrates, from substances allied to 
carbohydrates, and from albumin. It may be obtained artificially 
from butyric or stearic acid by oxidation ; and from tartaric and 
malic acids by reduction. 

Both normal and acid succinates, W^Q^f)^ and R^HC^H^O^, are 
known. A potassium hydrogen succinate, KHC^Hp^, H^C^H^O^, 
H^O, analogous to salt of sorrel, also exists. Soluble succinates 
give a bulky brown precipitate with neutral ferric chlorine (some- 
what less voluminous than ferric benzoate) ; a white precipitate 
with lead acetate, soluble in excess of either reagent ; with silver 
nitrate a white precipitate after a time ; with barium chloride no 
precipitate at first, but a white precipitate of barium succinate on 
the addition of ammonia and alcohol. Succinates are distinguished 
from benzoates by the last named reaction, and not by yielding a 
precipitate on the addition of acids [see p. 323). 

Tannic Acid, Gallotannic Acid, or Tannin. Digallio 
acid, Cj^HjjjOg, SHgO. — This is a very common astringent constit- 
uent of plants, but is contained in largest quantity in galls (excres- 
cences on the oak, formed by the puncture and deposited ova of an 
insect). English galls contain from 14 to 28 percent, and Aleppo 
galls {Galla, U. S. P.) 25 to 65 percent, of tannic acid (Acidum 
Tannicum, U. S. P.). 

Myrobalans, the dried immature fruits of Terminalia Chebula, 
the ''Chebulic myrobalans" of commerce, may be used in India 
and the Eastern Colonies instead of galls. The best contain about 
30 percent, of tannin. 

Gallotannic acid. . . C,H,(0H)3C0. 0. CeH2(OH)2COOH 

Gallic acid (p. 343)...C,H2(OH)3COOH 

Preparation. — Expose powdered galls (about an ounce is 
sufficient for the experiment) to a damp atmosphere for two 
or three days, and afterward add sufficient ether to form a 
soft paste. Let this stand in a well-closed vessel for twenty- 
four hours, then having quickly enveloped it in a linen cloth, 
submit it to strong pressure, so as to separate the liquid portion 
which contains the bulk of the tannic acid in solution. Reduce 
the pressed cake to powder, mix it with sufficient ether (to 
which one-sixteenth of its bulk of water has been added) to 
form again a soft paste, and press this as before. Mix the 
expressed liquids, and expose the mixture first to spontaneous 
evaporation and next to gentle heat until it has acquired the 
consistence of a soft extract ; then place it on earthen plates or 



TANNATE8. 341 

dishes, and dry it in a hot-air chamber at a temperature not 
exceeding 212° F. (100° C). 

The resulting tannic acid is a light brownish powder con- 
sisting of thin glistening scales, with a characteristic odor, a 
strongly astringent taste, and an acid reaction; readily soluble 
in water, and alcohol (90 percent.), very sparingly soluble in 
pure ether though soluble in the ethereal fluid used in the 
foregoing process (a mixture of ether, water, and alcohol — 
the latter contained as impurity in the ether.) 

The official preparations of tannic acid are Glyceritum Acidi 
Tannici, Ungiientum Acidi Taimici, and Trochisci Acidi 
Tannici. Tannic Acid Test Solution contains 1 part of Tan- 
nic acid in 1 part of alcohol and sufficient water to measure 
10 parts. 



Reactions of Tannic Acid. 

1. To an aqueous solution of tannic acid add aqueous solu- 
tion of gelatin ; a yellowish-white fiocculent compound of the 
two substances is precipitated. 

The above reaction also serves to explain the chemical principle 
involved in tanning — the operation of converting skin into leather. 
In this process the skin is soaked in infusion of oak -bark, the tan- 
nic acid of which, uniting with the gelatinous tissues of the skin, 
yields a compound very well represented by the above precipitate. 
The outer bark of the oak contains little or no tannic acid, and is 
commonly shaved off from the pieces of bark which are large 
enough to handle ; useless coloring matter is thus also rejected. 
Other infusions and extracts besides that of oak-bark (chiefly cate- 
chu, sumach, and valonia) are largely used by tanners ; if used 
alone, these act too quickly, and give a harsh, hard, less durable 
leather. The tannic acid of these preparations is slightly different 
from that of oak-bark. 

2. To an aqueous solution of tannic acid add a neutral solu- 
tion of a ferric salt ; dark bluish-black ferric tannate is slowly 
precipitated. This is an excellent test for the presence of 
tannic acid in vegetable infusions. The precipitate is the 
basis of nearly all black writing-ink. Ferrous salts give at 
first only a slight reaction with tannic acid ; but the liquid 
gradually darkens : characters written with a liquid of this 
kind, of proper strength, become quite black in a few hours, 
and are very permanent. 



342 THE ACID RADICALS. 

3. To an aqueous solution of tannic acid add solution of 
tartar-emetic ; antimony tannate is precipitated. This reaction 
and that with gelatin are useful in the quantitative determina- 
tion of tannic acid in various substances, the separation of the 
gelatin tannate being much promoted by previously adding 
some heavy neutral powder, such as barium sulphate, and 
well stirring while adding the gelatin. 

The variety of tannic acid which occurs in oak-bark is said to 
be a glucoside; that is, like many other substances, it yields glu- 
cose (grape-sugar) when boiled with dilute sulphuric or hydro- 
chloric acid, the other product being gallic acid. 

Gambir U. S. P., an extract of ourouparia Gambir ; as well as 
the true (or black) Catechu, Gutch, or Terra Japonica, an extract 
from Acacia Catechu and A. Sumah; the original African (Gambian) 
Kino, termed by the Mandingo natives Kano, from Fferocarpus 
erinaceus, but not now in commerce ; East Indian Kino {Kino, 
U. S. P.), from the Pterocarpus rnarsupium ; also Bengal or Butea 
Kino, from the Falas or Dhak tree, Butea frondosa; Botany Bay 
or Australian Kinos from various species of Eucalyptus or Blue 
Gum trees and some other vegetable products — contain a variety 
of tannic acid (rnirnotannic acid), which gives a greenish precipi- 
tate with neutral solutions of ferric salts. According to Paul and 
Kingzett this acid yields, when decomposed, unfermentable sugar, 
and an acid different from ordinary gallic acid. Catechu and 
Gambler also contain catechuic acid or catechin, CgiHjoOj,, a com- 
pound occurring in minute colorless acicular crystals and, like 
mimotannic acid, affording a green precipitate with ferric salts. 

The rind of the fruit of the pomegranate {Punica granatum) 
[Granatum, U. S. P.) contains tannic acid. The astringency of 
Pomegranate-root Bark is due to a tannic acid (its anthehnintic 
properties probably to a resinoid matter, or possibly to what 
Tanret states to be a liquid alkaloid). A tannic acid also prob- 
ably gives the astringency to logwood {Hcematoxylon U. S. P.). 
Rhatany-Yooi^Sirk {Krameria, U. S. P.) contains about 20 percent, 
of tannic acid, its active astringent principle ; rhubarb-root about 
9 percent. Bearberry leaves ( Uvce Ursi, U. S. P. ) owe most of 
their therapeutic jDower to about 35 percent, of tannic acid. (The 
cause of their influence on the kidneys is not yet traced.) They 
also contain arbutin, a crystalline glucoside. Larch Bark, the 
inner bark of Finus Larix or Larix Europoea, contains, according 
to Stenhouse, a considerable amount of a tannic acid giving olive- 
green precipitates with ferric salts, and larixin and larixinic add, 
C^j^Hj^Og, a somewhat bitter substance. Areca nuts or Betel nuts, 
from the Areca Palm [Areca Catechu), besides the alkaloid arekane 
(Bombelon), contain a very active alkaloid, arecoline, CgH^^NOg 
(Jahns), said to be the vermifugal principle; arecaine, an inert 



TANNATES. 343 

alkaloid (Jahns), and according to Fliickiger and Hiii.Mi4.xj, tiuuut 
16 percent, of 'tannic matter." Betel is also the name given to 
the leaves of Piper Betle. It contains volatile oils (Kemp), one 
constituent of which, chavkol (Eykman), appears to be character- 
istic. A mixture of the nuts and leaves with a little lime, known- 
shortly, as ''Betel," is universally used as a stimulating and exhila- 
rating masticatory by the natives in the East, meeting, apparently, 
some widespread physiological demand. The leaves of Pan (Hind. ) 
are also used in various other ways as a common household drug. 
The extract of the fruit of Gab or Diospyros embryopteris is a power- 
ful astringent containing tannic acid. The rhizome of Geranium 
raaculatum, Spotted Cranesbill, or Alum-root, and the leaves and 
stalks of Sumac, Sumach or Shumac {Bhus, various species) contain 
both tannic and gallic acids. The fruit of sumach {Bhus glabra, 
U. S. P. ) contains tannic and malic acids. Poison Ivy or Poison 
Oak contains poisonous toxicodendric acid especially in spring. 
The principal constituent of the root-bark of high blackberry 
{Bubus, U. S. P.) is tannic acid. Acacice Cortex, Acacia Bark or 
Babool, resembles oak-bark in containing tannic acid. 

Gallic Acid, C^'Rfi^,ILJd (p. 340) (Acidum Gallicum,, 
U. S. P.), occurs in small quantity in oak-galls and other vege- 
table substances, but is always prepared from tannic acid. 
Gallic acid forms slender acicular, fawn-colored crystals, solu- 
ble in 100 parts of cold or 3 of boiling water, freely soluble 
in alcohol, sparingly in ether. 

Boil one part of coarsely powdered galls with four fluid parts 
of dilute sulphuric acid for half an hour ; strain through calico 
while hot; collect the crystals that are deposited on cooling, 
and purify these by treatment with animal charcoal and by 
repeated crystallization. 

Tests. — To an aqueous solution of gallic acid add a neutral 
solution of a ferric salt ; a bluish-black precipitate of ferric 
gallate is produced, similar in appearance to ferric taunate. 
Ferrous salts are also blackened by gallic acid. To more of 
the solution add an aqueous solution of gelatin; no precipi- 
tate is formed. By the latter test gallic acid is distinguished 
from tannic acid. 

Pyrogallic acid or pyrogallol U. S. P., CpH3(OH)3. — This sub- 
stance sublimes in light feathery crystals when gallic acid is heated. 
Or it may be formed by heating gallic acid with 3 or 4 times its 
weight of glycerin to a temperature of 190° or 200° C. for a short 
time, until carbonic anhydride is no longer evolved. Longer heat- 
ing at a lower temperature is not equally effective, and below 
100° C. probably no pyrogallol is produced (Thorpe). To an 



THE ACID RADICALS. 

u4ucOUd solution add a neutral solution of a ferric salt; a red color 
is produced. To another portion add a ferrous salt ; a deep-blue 
color results. 

Test for the three acids, taniiie, gallic, and pyrogallic. — To 
three separate small quantities of milk of lime in test-tubes 
add, respectively, tannic, gallic, and pyrogallic acids ; the first 
slowly turns brown, the second more rapidly, while the pyro- 
gallic mixture at once assumes a beautiful purplish-red color 
changing to brown. These reactions are characteristic ; they 
are accompanied by absorption of oxygen from the air. 

Use of Pyrogallolin Gas-analysis. — A mixture of pyrogallol and 
solution of potassium hydroxide absorbs oxygen with such rapidity 
and completeness that concentrated solutions of each, passed up 
successively by means of a pipette into a graduated tube con- 
taining air or other gas, over mercury, form an excellent means 
of determining free oxygen. The value of this method may be 
proved roughly by pouring a small quantity of each solution into 
a bottle, immediately and firmly closing its mouth with a cork, 
thoroughly shaking the bottle, and then removing the cork under 
water: the water rushes in and occupies about one-fifth of the 
previous volume of air, indicating that the atmosphere contains 
one-fifth of its bulk of oxygen. The small quantity of carbonic 
anhydride present in the air is also absorbed by the alkaline 
liquid; in delicate experiments this should first be removed by 
means of the caustic alkali and the pyrogallol then be added. 

Thiocyanic Acid, HSCN, and other Thiocyanates. — 
Boil together sulphur and solution of potassium cyanide ; solu- 
tion of potassium thiocyanate, KSCN, is formed. Warm the 
liquid, add hydrochloric acid until it faintly reddens litmus- 
paper, and filter ; any potassium sulphide is thus decomposed, 
and the solution may then be used for the following reactions. 
The salt readily crystallizes. 

Tests. — To a small portion of the solution add ferric chlo- 
ride ; a deep blood-red solution containing ferric thiocyanate is 
formed. (Solutions of pure ferrous salts are not colored by 
thiocyanates. ) To a portion of the red liquid add a little 
hydrochloric acid ; the color is not discharged (ferric mecon- 
ate, a salt of similar tint, is decolorized by hydrochloric acid). 
In the acid liquid place a fragment or two of zinc ; hydrogen 
sulphide is evolved, and the red color disappears. 

To another portion of the ferric thiocyanate add solution 
of mercuric chloride ; the color is at once discharged. (Ferric 



THIOCYANATES. 

meconate is unaffected by mercuric chloride.) The reac^.^xx 
with ferric salts is the best test for the presence of a thio- 
cyanate ; and indirectly is also a good test for the presence of 
hydrocyanic acid or other cyanide (see p. 269). Red ferric 
acetate solution is decomposed by ebullition. Neither the 
ferric acetate nor the meconate yields its color to ether ; but, 
on shaking ferric thiocyanate solution with ether, the latter 
takes up the thiocyanate and becomes of a purple color. 

To a solution of a thiocyanate add solution of mercuric 
nitrate ; mercuric thiocyanate is precipitated as a white 
powder. 

Pharaoh's Serpents. — Mercuric thiocyanate, thoroughly washed 
and made up into little cones, forms the toy termed Pharaoh's 
serpent. It readily burns when ignited, the chief product being 
a light solid matter (melon, CgH^Ng, and melam, CgHgN^J, which 
issues from the cone in a snake-like coil of extraordinary length. 
The other products are mercuric sulphide (of which part remains 
in the residue and part is volatilized), nitrogen, sulphurous anhy- 
dride, carbonic anhydride, and vapor of metallic mercury. 

The thiocyanic radical (SON) is termed thiocyanogen. The 
thiocyanates were formerly called sulphocyanides. Saliva contains 
thiocyanates. 

Uric Acid, CgH^N^Og, and other Urates. — Acidulate 
a few ounces of human urine with hydrochloric acid and set 
aside for twenty -four hours ; a few minute crystals of uric acid 
will be found adhering to the sides and bottom of the vessel 
and floating on the surface of the liquid. 

Microscopical Test. — Place some of the floating particles on 
a slip of glass, and examine them under a powerful lens or a 
microscope ; the chief portion will be found in the form of 
more or less square, yellowish, semi-transparent crystals, two 
of the sides of which are even, and two very jagged ; but other 
forms are common. 

Chemical Test. — Collect more of the deposit, place in a 
watch-glass or small white evaporating-dish, remove adherent 
moisture by means of filter-paper, add a drop or two of con- 
centrated nitric acid, and evaporate to dryness ; the residue 
will be red. When the dish is cold, add a drop of ammonia 
water ; a purplish-crimson color results. The color is deepened 
on the addition of a drop of solution of potassium hydroxide. 

Notes. — Uric acid (or lithic acid) and sodium, potassium, cal- 
cium, and annnonium urates (or lithates) are common constituents 



G t8 THE ACID RADICALS. 

of animal excretions. Human urine contains about one part of 
urate (usually sodium urate) in 1000. When more than this 
is present, the urate is often deposited as a sediment in the excreted 
urine, either at once, or after standing a short time. Uric acid 
or other urate is also occasionally deposited before leaving the 
bladder, and, slowly accumulating there, forms a common variety 
of urinary calculus. — Some urates are not definitely crystalline ; 
but, when treated with dilute nitric acid or a drop of solution of 
potassium hydroxide and then a drop or two of acetic acid, micro- 
scopic crystals of uric acid are usually formed. — All urates yield 
the crimson color when treated as above described. This color is 
due to a definite substance, murexid, CgHgXgOg, (from murex, a 
shell-fish of similar tint, from which the ancient and highly valued 
purple dye seems to have been prepared), and the test is known 
as the murexid test. The formation of murexid is due to the 
action of ammonia on alloxan, CJl^fi^, 4H^0, and other white 
crystalline products of the oxidation of uric acid by nitric acid. 
Murexid is a good dye ; it may be prepared from guano (the excre- 
ment of sea-fowl), which contains a large quantity of ammonium 
urate. — The excrement of the serpent is almost pure ammonium 
urate. 

Uric acid and the urates w411 again be alluded to in connection 
with the subject of morbid urine. 

Constitution of Uric Acid. — The physiological and pathological 
importance of uric acid has obtained for it great attention from 
chemists. For accounts of what has been done in recent years 
toward elucidating its constitution, students of organic chemistry 
may consult the Pharmaceutical Journal, 3rd Series, vol. xiv., 
p. 771 ; vol. XV,, pp. 119 and 411 ; and vol. xviii., p. 69. 

Valeric Acid or Valerianic Acid, HCHgO^, and 
OTHER Valerates. — In a test-tube place a few drops of amyl 
alcohol (fusel-oil, which is impure amyl alcohol, may be used) 
with a little dilute sulphuric acid aud a grain or two of potas- 
sium dichromate, cork the tube, set aside for a few hours, and 
then heat the mixture ; valeric acid of characteristic valerian- 
like odor, is evolved. 

Valeric acid occurs in valerian-root in association with the essen- 
tial oil from which it is apparently derived {see p. 471), but is 
usually prepared artificially, by the foregoing process, from amyl 
alcohol, to which it bears the same relation that acetic acid does 
to common alcohol : — 

C,H,OH + 20 = HC2H3O2 + HP 
C5H11OH + 20 - HC.HgO, + H,0 

Sodium Valerate, NaC.HgOg, is prepared from the valeric acid 
and amyl valerate obtained on distilling a mixture of amyl alcohol, 



VALERATES. 347 

sulphuric acid, potassium dichromate, and water. Tiie mixture 
should stand for several hours before heat is applied. 

C.H^.OH + 20 = HC5H9O, + H,0 

Amyl alcohol Oxygen Valeric acid Water 

2C H OH + ^ 20 = C,H„C,H,0, + 2H,0 
Amyl alcohol Oxygen Amyl valerate Water 

The distillate is saturated with sodium hydroxide, which not 
only yields sodium valerate with the free valeric acid, but also 
decomposes the amyl valerate produced at the same time, more 
sodium valerate being formed and some amyl alcohol set free, 
according to the following equations : — 

HC5H9O2 + NaOH = NaC.HgO^ + H^O 

Valeric acid sodium hydroxide Sodium valerate Water 

aH^^C.H.O^ + NaOH -= NaC^H^O^ + C^H^OH 

Amyl valerate sodium hydroxide Sodium valerate Amyl alcohol 

From the solution of sodium valerate (which should be made neu- 
tral to test-paper by careful addition of sodium hydroxide solution) 
the solid white salt is obtained by evaporation to dryness and cau- 
tious fusion of the residue. The mass obtained on cooling should 
be broken up and kept in a well-closed bottle. It should be entirely 
soluble in alcohol. 

Other Valerates, as zinc valerate, Zn{C^Ilfi^)^ {Zinci Valeras, 
U. S. P.), and ferric valerate, Fe{C^'Rfi^)^, may be made by the 
interaction of sodium or other valerate and the sulphate or other 
salt of the metal the valerate of which is desired, the new valerate 
either precipitating or crystallizing out. A hot solution of zinc 
sulphate (5f parts) and sodium valerate (5 parts) in water (40 parts) 
gives a crop of crystals of zinc valerate on cooling. Ammonii 
Valeras, U. S. P., in white lamellar crystals, results when dry 
ammonia gas is passed into valeric acid. 

Tests. — Heated with dilute sulphuric acid valerates of the 
metals give a highly characteristic smell (valeric acid). 

Note. — Of the four possible varieties of valerates, the foregoing 
are the ordinary or iso-valerates, the constitutional formula for the 
acid being (CH^), = CH — CH^ — COOH. See the Acetic Series 
of Acids in the Section on Organic Chemistry. 

The amyl alcohol (C^Hj^OH) from which valerates are prepared 
may contain the next lower member of the homologous series of 
alcohols, butyl alcohol, C^HgOH. This alcohol, during the oxi- 
dation, will be converted into butyric acid, HG^H.O.,, the next 
lower homologue of valeric acid, HCr^H.jOj, and hence the various 
valerates may be contaminated by some biityratcs. These are 
detected by distillation with dilute sulphuric acid and addition of 



348 THE ACID RADICALS. 

solution of cupric acetate to tlie distillate, which at once becomes 
ir; i'Md if butyric acid be present. In this reaction valeric acid and 
d butja-ic acid are produced by interaction of the valerate and 
butyrate and the sulphuric acid, and they distill over on the appli- 
cation of heat. On the addition of cupric acetate, Cu(C.^H302)2, 
cupric butyrate, Cu(CiH.02)2, is formed, and, being almost 
insoluble in water, is at once precipitated, or remains suspended, 
giving a bluish white opalescent liquid. Cupric valerate, 
Cu(C-H902)2, is also formed after some time, but is far more soluble 
than the butyrate, and only slowly collects in the form of greenish 
oily drops, which gradually pass into greenish-blue hydrous crys- 
talline cupric valerate (Larocque and Huralt). 



QUESTIONS AND EXERCISES. 

Mention a test for nitrites in potable waters. —Which nitrates are 
official? — Give the names of some natural and artificial silicates. — ''What 
is soluble glass" ? — Distinguish between silica and silicic acid. — How are 
silicates detected ? — What is the quauti valence of silicon ? — Mention the 
sources, formulae, and analytical reactions of succinates. — State the mode 
of manufacture of and tests for thiocyanates. — What proportion of tannic 
acid is contained in galls? — Describe the process for the preparation of 
tannic acid. — Explain the chemistry of "tanning." — Enumerate the tests 
for tannic acid. — What is the formula for tannic acid? — Mention official 
substances other than galls whose astringency is due to tannic acid. — 
How is gallic acid prepared ? — By what reaction is gallic acid distinguished 
from tannic acid ? — Mention the characteristic properties of pyrogallic 
acid. — Explain the murexid test for uric acid. — Describe the artificial 
preparation of valeric acid and other valerates, giving equations. — What 
is the formula of valeric acid ? — How are butyrates detected in presence 
of valerates ? 



DETECTION OF THE ACID RADICALS OF 
SALTS SOLUBLE IN WATER. 

In examining a salt soluble in water, and concerning which no 
general information is obtainable, search must first be made for 
the metallic radical by the appropriate methods (see pp. 338, 342, 
etc.). The metal having been detected, consideration of the 
character of its salts will indicate which acid radicals may be, and 
which cannot be, present. Thus, for instance, if the substance 
under examination is freely soluble in water and lead is found, 
only the nitric and acetic radicals need be sought, none other of 
the lead salts than nitrate or acetate being freely soluble in water. 
Moreover the salt is more likely to be lead acetate than nitrate, 
for two reasons: the former is more soluble than the latter, and 
is by far the commoner salt of the two. Medical and pharmaceuti- 
cal students have probably, in dispensing, already learnt much 



ANALYTICAL DETECTION OF ACID RADICALS. 349 

concerning the solubility of salts, and whether a salt is rarely- 
employed or is in common use. And although but little depend- 
ence can be placed on the chances of a salt being present or absent 
according to its rarity, still the point may have its proper weight. 
If, in a mixture of salts, ammonium, potassium, and magnesium 
have been found associated with the sulphuric, nitric, and hydro- 
chloric radicals, and we are asked how we suppose these bodies may 
have existed in the mixture, we are much more likely to be correct 
if we suggest that sal-ammoniac, nitre, and Epsom salt were 
originally mixed together, than if we suppose any other possible 
combination. Such appeals to experience regarding the solubility 
or rarity of salts cannot be made by any one unacquainted, or 
insufficiently acquainted, with the characters of salts; in such 
cases the relation of a salt to water and acids can be ascertained 
by referring to the following Table (p. 351) of the solubility or 
insolubility of about five hundred of the common and rarer salts 
met with in chemical operations. 

The alternative course to the above (namely, to ascertain which 
acid radicals are present in a mixture, and then to appeal to 
experience to tell which metallic radicals may be and which can- 
not be present) is impracticable; for acid radicals cannot be sepa- 
rated out, one after the other, from one and the same quantity of 
substance by a similarly simple treatment to that already given for 
metallic radicals. Indeed such a separation of acid radicals could 
scarcely be accomplished at all, or only by a vast amount of labor. 
The metallic radicals must therefore be detected first. 

Even when the metallic radicals have been found, the acid radi- 
cals which may be present must be sought for singly, the chief 
additional aid which can be brought in being the action of sul- 
phuric acid, a barium salt, a calcium salt, silver nitrate, and ferric 
chloride on separate small portions of the solution under examina- 
tion, as detailed in the second of the following Tables. 

Qualitative Analysis. 

Before commencing the analysis of an aqueous solution of a 
salt or salts, the metallic radicals in which are known, ascer- 
tain which acid radicals may be, or, -what comes to the same 
thing, which cannot be present. To this end, consult the 
following Table (p. 351) of the solubility of salts in water. 
Look for the name of the metal of the salt in the vertical 
column ; the letters S and I indicate which salts are soluble 
and which insoluble in water, an asterisk attached to the S 
meaning that the salt is slightly soluble. 

Some of the salts marked as insoluble in water are soluble in 
aqueous solutions of soluble salts, a few forming soluble double 



350 THE ACID RADICALS, 

salts. To characterize salts as soluble, slightly soluble, or insolu- 
l>le, only roughly indicates their relation to water: on the one 
Ti'i^^d, very few salts are absolutely insoluble in water; on the other, 
' aere is a limit to the solubility of every salt. 

If only one, two, or perhaps three given acid radicals can he 
preserit in the solution, test directly for it or them according to 
the reactions given in the previous pages. If several may he 
present pour small portions of the solution, rendered neutral 
if necessary by addition of ammonia, into five test-tubes, and 
add respectively sulphuric acid, barium nitrate or chloride, 
calcium chloride, silver nitrate, and ferric chloride ; then con- 
sult the Table on p. 352, in order to interpret correctly the 
effects these reagents may have produced. 

Eemarks on the Table, p. 352. 

The first point of value to be noticed in connection with this 
Table, is one of a negative character; namely, if either of the 
reagents gives no reaction, it is self-evident that the salts which it 
decomposes with production of a precipitate must be absent. Then, 
again, if the action of one of the reagents indicates the absence of 
certain acid radicals, those radicals cannot be among those precipi- 
tated by the other reagent; thus, if the action of sulphuric acid 
points to the absence of sulphides, sulphites, carbonates, cyanides, 
and acetates, these salts may be struck out of the other lists, and 
the examination of subsequent precipitates is so far simplified. 
Or, if the barium precipitate is soluble in hydrochloric acid and 
the calcium precipitate in acetic acid, neither sulphates nor oxa- 
lates can be present. Observing these and other points of difference, 
which will be seen on careful and thoughtful reflection, and 
remembering the facts suggested by a knowledge of what metallic 
radicles are present, one acid radical after another may be struck 
off as absent or present, leaving only one or two as the objects 
of special expeiament. Among the chief difiiculties to be encoun- 
tered will be the separation from each other of chlorides, bromides, 
iodides, and cyanides, or of tartrates from citrates, and confirmatory 
tests of the presence of certain compounds. These may all be sur- 
mounted on referring back to the reactions of the various radi- 
cals as described under their hydrogen salts, the acids. 

In rendering a solution neutral, for the application of the various 
group-tests, the necessary employment of any large amount of acid 
or of alkali must be noted, the presence of alkaline hydroxides or 
of free acids, respectively, being thereby indicated. The presence 
of free acid is usually indicated by the ahundant effervescence 
which results on the addition of a carbonate. 

Sulphuric acid, the first group-reagent, may itself yield by 
reduction, especially when heated with certain solid substances, 



QUALITATIVE ANALYSIS. 



351 






5 5 ^-2 S III P'^^^ 



-•§oB 



S ^ ff C3 



*= • .^ : e. I c ^ B o § t3 



1-^ 






a2a!a2QCOQ02GO-^GCa!Q00202(X!->5a2QDQDGCiXlCCQDGOa5QDQCijO 



Ml— 11— I^^SQOl— iQDl— IHHI— II— IHHMI— (Ml— ItHMI— IM M*>> ->»M I— (CO M 



•^t— (Ml— (COI— iCO-oi— IMhH->S|— (W<'t— II— IMM^M-^-^si— IMCOl 



HHM-^*^C0MG0->»MMI— (I— (I— (I— (•■>»(— l*<'l— II— IMh- II— (I— II— I'^CCM 



QDaJOQQCr/JMOQQCQOMCOCOiKGOGCGOaDCOGOQCCDaQQOQDfKQDDD 



zci-i^-^'ZCi^m-oWi-^-o^mm-owwmzcimznwwza-^zcm 



Arsenate. 



Carbonate. 



Chloride. 



Citrate. 



qqmi-ii— iCCMGD^^sMMCOODOOM-o-oOOOD-^i-iGO-^i-ii-it-iGCi-i Chromate. 





1— (OQ'-C'-c>ijOl— iGO-<it— l-^COi— I'-oMMI— l--tol— II— 11— iCO-hO'-oQD'-oGO-c 


Cyanide. 


#■ 


-^0CMMCO-<.GOi-ll-|.>5l-(KHM;5_l-IMI-IM(-IMqQ|-|l-lGOMQCM 


Hydroxide. 




QDJMOiasOQMCOQCCOMI-lGOCOOpMGCQDMQOaSCCCCMCOl-iCC-^ 


Iodide. 




muimmmuimmuimifiuimm.^uiminuiuiuiuiuim^wui 


Nitrate. 




MMMa!02MCC.^MMI-IMMM->sCCQpMI-lQ0MI-ll-ll-lG0Q0M 


Oxalate. 




MC»MM^MGOMMMMMMMMM^MMM^MMC»M..M 


Oxide. 




MMMI-lCKl-iaJ^HHI-ll-ll-ll-IMMI-lhrlMI-IMI-ll-ll-ll-IMCCM 


Phosphate. 




iXir-iUiuimmuimmmiriuimy^'<>iJiTjixriUiuiwmuiy-i^xfim 


Sulphate. 




MGDMMCOmGOI-II-II-I I-*I-I -cl-ll-ll-ll-IMI-ll-iq2MI-lQ0l-lC0l-l 


Sulphide. 




0rjMl-l-^CCl-lC002C0-^->sC0C0l-l-oG0.-oi-iC0C0C0C0(-iMMC0M 


Sulphite.. 




&Qq2OQ.^O0MGO.<.QOMMQOa!M-->5GO(X!COCOGCCOCOl-IMMCOCO 


Tartrate. 



II 



THE ACID RADICALS. 



a < 

H 



^"^ s 



<1 H 

Eh 
O < 
H p^ 

O 
H pa 

pq 






^ ft 



S is 

.2 2 

o ft 



ft 

^ ft 



O 09 
^ W 

ftg 



II ^1 

^ 2, an 



5-5 1 -S -^ 



"S 5fi rt ^ cs ^i 



-r C3 O -ph 

=« iJ fl ^ 

O O Ph 



^ a. 



<D ^ 






"B "B ^ ^ 



Q W M 



l^.€? 



-2s -"t; <u Qj 
•-H ja t^ -H 



p, p. 









c3 



2QCCCCOOHP-(0 









o >, 



^^-3^ s S^o >-^ 



^13 



O U 

-p .ti 

P-( O 






^ aS o.t5 5g a g >^ S-S ^S Co ^ 
a 2 a|S £-32 0x2 = 29^.5 






o 2 s 5« o 






3 

^5 a' 






2 5 rC) :s « ^ jTrrt a ° 




o2 3 tSX c3f3.-SO 






J2XI 



^2 



a ^'- 






o o oj 



ja c3 



5&:^ 



QUALITATIVE ANALYSIS. 353 

sulphurous acid or hydrogen sulphide {see pp. 288 and 290); hence 
the production of these from a diluted solution should alone be 
regarded as evidence of the presence of a sulphide or sulphite. 

Calcium chloride does not precipitate citrates readily or com- 
pletely in the cold: therefore the mixture should be filtered and 
the filtrate boiled; calcium citYate then separates. Calcium tar- 
trate is soluble in solution of ammonium chloride when quite 
freshly precipitated, but not after it has become crystalline. 
From their solutions in ammonium chloride, calcium tartrate is 
mostly precipitated by ammonia, and calcium citrate on boiling. 

The rarer acid radicals will be very seldom met with. The 
presence of benzoates, hippurates (which give benzoic acid), hypo- 
chlorites, thiosulp hates, nitrites, and valerates will be indicated 
during the treatment with sulphuric acid. Ferrocyanides, Jerri- 
cyanides, meconates, succinates, thiocyanates, tannates, and gallates 
are among the salts whose presence is indicated by ferric chloride; 
formates, hypophosphites, malates, and others are indicated by silver 
nitrate. Urates char when heated, giving an odor resembling 
that of burnt feathers. 

In actual practice the analyst nearly always has some clue to 
the nature of rarer substances placed in his hands. 

If chromium and arsenic have been detected among the metallic 
radicals, these elements may be present in the form of chromates 
arsenates, and arsenitcs, yielding with barium chloride yellow 
barium chromate and white barium arsenate and arsenite, and with 
silver nitrate red silver chromate, brown silver arsenate, and yellow 
silver arsenite. 



QUESTIONS AND EXERCISES. 
In analyzing an aqueous solution of salts, for which radicals would you 
first search, the metallic or the acid, and why? — In an aqueous solution 
there have been found magnesium (Mg) and potassium (K), with the 
sulphuric radical (SO4), and iodine (I) ; state which salts were probably 
dissolved originally in the water, and mention the considerations which 
giiide you to the conclusions. — Give a sketch of the methods by which 
you would examine a neutral or only faintly acid aqueous liquid for the 
acid radicals which might be present. In what stages of the examination 
would the following salts be detected? a. Carbonates and Sulphates. 
h. Oxalates, c. Tartrates and Nitrates, d. Acetates and Sulphites., 
e. Bromides and Cyanides. /. Borates. g. Iodides and Phosphates. 
h. Chlorates, Oxalates, and Acetates, i. Chlorides and Iodides, j. Sul- 
phites, fc. Sulphides, Carbonates, and Nitrates. I. Citrates and Sul- 
phates. — Silver nitrate gives no precipitate in a given aqueous solution ; 
what acid radicals may be present? — Barium chloride gives no precipi- 
tate in a given neutral solution, but silver nitrate gives a white precipi- 
tate; what acid radicals are indicated? — Ferric chloride produces a 
deep-red color in a solution, calcium chloride yielding no precipitate ; 
what salts may be present, and how may they be distinguished from each 
other? — Fei-ric chloride gives a black precipitate in a solution in which 
sulphuric acid develops no odor ; to what is the eftect due ? 

23 



354 QUALITATIVE ANALYSIS. 

ANALYSIS OF SALTS. 
SINGLE OR MIXED, SOLUBLE OR INSOLUBLE. 

Thus far, most of the substances which have been considered, 
especially those of pharmaceutical interest, have been regarded as 
definite compounds, and as having certain well-defined radicals 
termed metallic and acid respectively: moreover attention has been 
designedly restricted to those definite compounds which are 
soluble in water. But there still are numerous substances having 
no definite or known composition; and of those having definite 
composition there are many having no definitely ascertained 
radicals. Again, of those having definite composition, and whose 
constitution has been in part or entirely elucidated, there are 
many insoluble in water. 

Chemical substances of whose composition or constitution little 
or nothing is at present known, are chiefly of animal and vegetable 
origin ; they are not of immediate importance, and may be omitted 
from consideration here. 

Of substances which are definite in composition, but whose 
parts or radicals are unknown or imperfectly known, there are 
only a few (such as the alkaloids, amylaceous and saccharine 
matters, the glucosides, and the albuminoid, resinoid, and animal 
and vegetable coloring matters) which have any considerable 
amount of medical or pharmaceutical interest ; these will be 
noticed subsequently. 

Definite compounds most frequently present themselves ; and 
of these by far the larger proportion (namely, the salts soluble in 
water) have already been studied. There remain, however, many 
salts which are insoluble in water, but which must be brought 
into a state of solution before they can be effectively examined. 
The next subject of laboratory work is, therefore, the analysis of 
substances which may or may not be soluble in water. This will 
involve no other analytical schemes than those which have been 
given, and will in only one or two cases increase the difficulty of 
the analysis of a precipitate produced by a group-reagent ; but it 
will give roundness, completeness, and a practical bearing to the 
student's analytical knowledge. Such laboratory work will at the 
same time bring into notice the methods by which substances 
insoluble in water are manipulated for pharmaceutical purposes, 
or are made available for use as food for plants, or as food or 
medicine for man and animals generally. 

Preliminary Examination of Solid {chiefly mineral) Salts. 

Before attempting to dissolve a salt for analysis, its appearance 
and other physical properties should be noted, and the influence 
of heat and concentrated sulphuric acid should be ascertained. 
Unless the operator knows how to interpret what is thus observed, 



QUALITATIVE ANALYSIS. 355 

and to what extent he can place confidence in his observations, 
he should omit the preliminary examination altogether, except 
when he is able to follow it out under the guidance of a judicious 
teacher; for it is impracticable here to do more than hint at the 
results which may be obtained by such an examination, or so to 
adapt descriptions as to prevent a student allowing unnecessary 
w^eight to attach to preconceived ideas. 

Whatever be the course pursued, short memoranda describing 
results should invariably be entered in the note-book. 

1. Examine the physical characters of the salt in various 
ways, but only rarely and cautiously, by the palate, on 
account of the danger of so doing. 

If the salt is, to the eye, white, little more than traces of 
distinctly colored substances can be present; if colored, the tint 
may indicate the nature of the substance or of one of its constit- 
uents, supppsing that the student is already acquainted with the 
colors characteristic of certain salts. Closer observation, aided 
perhaps by a lens, may reveal the presence, in a pulverulent 
mixture, of small crystals or pieces of a single substance; these 
should be picked out by means of a needle or forceps and examined 
separately. In a powder or roughly pulverized mixture of sub- 
stances, the process of sifting (through such sieves as muslin of 
different degrees of fineness) often mechanically separates sub- 
stances, and thus greatly facilitates analysis. The substances 
may present an undoubted metallic appearance, in which case 
only the metals existing under ordinary atmospheric conditions 
need, as a rule, be sought for. Peculiarity in smell reveals the 
presence of ammonia, hydrocyanic acid, hydrogen sulphide, etc. 
Between the fingers a substance is, perhaps, hard, soft, or gritty, 
and from such a character useful inferences may be drawn. Or 
the substance may be heavy, like the salts of barium or lead, or 
light, like the magnesium carbonates and oxides ; or it may be 
one of the pharmaceutically well-known class of ''scale" pre- 
parations. 

2. Place a grain or two of the salt in a dry test-tube or in 
a piece of glass tubing closed at one end, and heat it, at first 
gently, then more strongly, and finally, if necessary, in the 
blowpipe-flame. 

Gases or vapors of characteristic appearance or odor may be 
evolved, such as iodine, nitrous fumes, sulphurous anhydride, 
hydrocyanic acid, or ammonia. Much steam given off by a dry 
substance indicates either hydroxides or salts containing water of 
crystallization. (A small quantity of interstitial moisture often 
causes heated crystalline substances to decrepitate — irom decrepo, 



III 



356 QUALITATIVE ANALYSIS. 

I crackle — that is, break up with slight explosive violence, owing 
to the expansive force of the steam suddenly generated.) A 
sublimate may result, , due to salts of ammonium, mercury, or 
arsenic, to oxalic or benzoic acid, or to sulphur free or as a sul- 
phide — a salt wholly volatile containing such substances only. 
The compound may blacken, pointing to the presence of organic 
matter — Avhich, in ordinary salts, will probably be in the form of 
acetates, tartrates, and citrates, or as common salts of the alkaloids 
morphine, quinine, strychnine, or as starch, sugar, salicin ; or it 
may be in other definite or indefinite forms common in pharmacy, 
and for which tests will be given in subsequent pages. If no 
charring occurs, the important fact is established that organic 
matter is not likely to be present — except perhaps cyanides, 
formates, or oxalates, which do not char. The residue may 
change color fi'om the presence or development of zinc oxide, iron 
oxide, etc., or melt from the presence of a fusible salt and absence 
of any large proportion of infusible salt, or be imaltered, showing 
the absence of any large amount of such substances. 

3. Place a grain or two of the salt in a test-tube, add a 
drop or two of concentrated sulphuric acid, cautiously smell- 
ing any gas that may be evolved ; afterward slowly heat the 
mixture, noticing the eflfect, and stopping the experiment 
when any sulphuric fumes begin to escape. 

Iodine, bromine, and nitrous or chlorine-like fumes will reveal 
themselves by their color, indicating the presence of iodides, 
iodates, bromides, bromates, nitrates, and chlorates. The evolu- 
tion of a colorless gas, fuming on coming into contact with air 
and having an irritating odor, points to chlorides, fluorides, or 
nitrates. Gaseous products having a greenish color and odor of 
chlorine indicate chlorates, hypochlorites, or chlorides mixed with 
other substances. Slight sharp explosions betoken chlorates. 
Evolution of colorless gas may proceed from cyanides, acetates, 
sulphides, sulphites, carbonates, or oxalates. Charring will be 
due to citrates, tartrates, or other organic matter. If none of 
these effects is produced, most of the above-named substances are 
absent or only present in minute proportion. The substances 
apparently unaffected by the treatment are metallic oxides, 
borates, sulphates, and phosphates. 

4. Expose some of the substance to the blow-pipe flame on 
platinum wire, with or without a bead of borax or of micro- 
cosmic salt^ (sodium, ammonium, hydrogen phosphate, 
NaNH^HPO^, 411,0 ) ; on platinum foil, or in a porcelain 
crucible, or on a crucible lid, with or without sodium carbon- 

' So called because formerly obtained from the urine of man, who was 
called the microcosmos or little world. 



SOLID SUBSTANCES. 357 

ate ; or on charcoal, alone or in conjunction with sodium car- 
bonate, potassium cyanide, or cobalt nitrate. This experiment 
will sometimes yield important information, especially to one 
who has devoted much attention to reactions producible by the 
blow-pipe flame. The medical or pharmaceutical student, 
however, will seldom have time to work out this subject to an 
extent sufficient to make it a trustworthy guide in analysis. 

Methods of Dissolving and Arialyzing Single or Mixed 
Solid Suhstances. 

Saving submitted the substance to preliminary examination, 
proceed to dissolve and analyze by the following methods. These 
operatio7is consist in treating the well-powdered substance con- 
secutively with cold or hot ivater, hydrochloric acid, nitric acid, 
nitro-hydrochloric acid, or fusing alkali-metal carbonates and 
dissolving the product in water and acid. The resulting liquids 
are analyzed in the manner already described, or by slightly 
modified processes as detailed in the following paragraphs. 

Solution in Water. — Boil about a grain of the salt presented 
for analysis in about a third of a test-tubeful of water. If it 
dissolves, prepare a solution of about 20 or 30 grains in 
half an ounce or more of water, and proceed with the analy- 
sis in the usual way, testing first for the metallic radical 
or radicals by the proper group-reagents (HCl, H^S, NH^SH, 
(NHJ^C03,(NHJ^HP0J, p. 242, and then for the acid 
radical or radicals, directly or by the aid of the prescribed 
reagents (H^SO,, BaCl,, CaCl,, AgNO,, FeCl3), p. 352. 

If the salt is not wholly dissolved by the water, ascertain 
whether or not any has entered into solution, by filtering, if 
necessary, and cautiously evaporating a drop or two of the 
clear liquid to dryness on platinum foil ; the presence or 
absence of a residue gives the information sought for. If any- 
thing is dissolved, prepare a sufficient quantity of solution for 
analysis and proceed as usual, reserving the insoluble portion 
of the mixture, after thoroughly exhausting with water, for 
subsequent treatment with acids. 

Solution in Hydrochloric Acid. — If the salt is insoluble in 
water, digest about a grain of it (or of the insoluble portion 
of a mixed salt) in a few drops of hydrochloric acid, adding 
water and boiling if necessary. If the salt wholly dissolves, 
prepare a sufficient quantity of the liquid, noticing whether 
or not any effervescence (due to the presence of sulphides, 
sulphites, carbonates, or cyanides) occurs, and proceed with 



358 



QUALITATIVE ANALYSIS. 



the analysis as before, except that the first step, the addition 
of hydr^ chloric acid, may be omitted. 

The ajialysis of this solution will in most respects be simpler 
than that of an aqueous solution inasmuch as the majority of salts 
(all those soluble in water) will be absent. This acid solution 
will, in short, only contain : — chlorides produced by the action of 
the hydrochloric acid on sulphides, sulphites, carbonates, cyanides, 
oxides, and hydroxides ; and certain borates, oxalates, phosphates, 
sulphates, tartrates, and citrates (possibly silicates and fluorides), 
which are insoluble in water, but soluble in acids without 
apparent decomposition. Sulphides, sulphites, carbonates, and 
cyanides will have revealed themselves by the occurrence of effer- 
vescence during solution; and the presence of oxides and hydroxides 
may (p. 361) be inferred by the absence of compatible acid radicals. 
The borates, oxalates, phosphates, tartrates, and citrates alluded of 
will be reprecipitated in the systematic analysis as soon as the acid to 
the solution is neutralized ; that is, will come down as such when 
ammonia and ammonium hydrosulphide are added in the usual 
course. Of these precipitates, only the calcium oxalate and the cal- 
cium and magnesium phosphates need occupy attention now, for ba- 
rium oxalate and phosphates seldom or never occur, and the borates, 
tartrates, and citrates met with in medicine or general analysis, are 
all soluble in water. These phosphates and, oxalates, then, will be 
precipitated in the course of analysis along with iron, their presence 
not interferring with the detection of any other metal. If, from the 
unusually light color of the ferric precipitate, phosphates and oxal- 
ates are suspected, it is treated according to the following Table : — 

Precipitate of Phosphates, Oxalates, Ferric 
Hydroxide, etc. 
Dissolve in HCl, add citric acid, then NH^OH, and filter ; 
then follow the Table below. 



Filtrate 

Fe 

Add HCl and 

K,Fe(CN)e 

Blue ppt. 



Precipitate 
Ca3_(P04),, CaCA, Mg^CPOJ, 
Boil in acetic acid, and fiker. 



Insoluble 

CaC,0,i 

White 

(CaF., may 

occur here) 



Filtrate 

Ca,(POJ„ Mg3(P0J, 
Add (NHJ2C2O4, stir, filter. 



Precipitate 

white 
indicating 

Ca3(P0J, 



Filtrate 

add XH.OH. 

White ppt. 

MgNH.PO, 



* Most oxalates, after ignition, effervesce on the addition of acid ; fluor- 
ides may be detected by the " etching " test. 



SOLID SUBSTANCES. 359 

In analyzing phosphates and oxalates, advantage is also 
frequently taken of the facts that the phosphoric radical is wholly 
removed from solution of phosphates in acid by the. "edition of 
an alkali-metal acetate and ferric chloride, and subsequent ebul- 
lition, as described under "Phosphoric Acid" (p. 316), and that 
dry oxalates are converted into carbonates by ignitiion as mentioned 
under "Oxalic Acid" (p. 304). 

Certain arsenates and arsenites, insoluble in water but soluble 
in hydrochloric acid, may accompany the above phosphates and 
oxalates if from any cause hydrogen sulphide has not previously 
been passed through the solution, or has only been passed for an 
insufficient length of time. 

If the substance insoluble in water does not wholly dissolve 
in hydrochloric acid, ascertain if any has entered into solution, 
by filtering, if necessary, and evaporating a drop of the clear 
liquid to dryness on platinum foil; the presence or absence of a 
residue gives the information sought for. If anything is dis- 
solved, prepare a sufficient quantity of solution for analysis, 
and proceed as usual, reserving the insoluble portion of the 
mixture, after thoroughly exhausting with hydrochloric acid 
and well washing with water, for the following treatment by 
nitric acid. 

Solution in Nitric Acid. — If the salt is insoluble in water 
and hydrochloric acid, boil it, (or that part of it which is 
insoluble in these menstrua) in a few drops of nitric acid. If 
it wholly dissolves, remove excess of acid by evaporation, 
dilute with water, and proceed with the analysis. 

This nitric acid solution can contain only a few substances; for 
nearly all salts soluble in nitric acid are also soluble in hydrochloric 
acid and, therefore will have been removed previously. Some of 
the metals, however (Ag, Cu, Hg, Pb, Bi), as well as amalgams 
and alloys, unaffected or scarcely affected by hydrochloric acid, 
are readily attacked and dissolved by liitric acid. Many of the 
sulphides, also, insoluble in hydrochloric acid, are dissolved by 
nitric acid, usually with separation of sulphur. Calomel is con- 
verted, by long boiling with nitric acid, into mercuric chloride 
and nitrate. The nitrates here produced are soluble in water. 

The nitric acid solution, as well as the hydrochloric acid and 
aqueous solutions, should be examined separately. Apparently, 
time would be saved by mixing the three solutions together and 
making one analysis. But the object of the analyst is to separate 
every radical from every other ; and when this has been partially 
accomplished by solvents, it would be unwise to again mix and 
separate a second time. Moreover, solvents often do what the 
chemical reagents cannot do — namely, separate salts from each 



;00 QUALITATIVE ANALYSIS. 

•: : '! r This is important, inasmuch as the end to be attained as far 
as possible in analysis is not only an enumeration of the radicals 
present, but a knowledge of the actual condition in which they 
are present; the analyst must state, when this is possible, of what 
salts a given mixture was originally formed — how the metallic and 
acid radicals were originally distributed. In attempting this, 
much must be left to theoretical considerations, and it is often 
impossible to arrive at certainly accurate conclusions ; but a pro- 
cess by which the salts themselves are separated is of practical 
assistance, hence the chief advantage of analyzing separately the 
solutions resulting from the action of water and acids on a solid 
substance. 

Solution in Nitro-hydrochloric Acid. — If the salt or any 
part of a mixture of salts is insoluble in water, hydrochloric 
acid, and nitric acid, digest it iu nitro-hydrochloric acid, 
warming, or even boiling gently, if necessary ; evaporate to 
remove excess of acid, dilute, and proceed as before. 

Mercuric sulphide and substances only slowly attacked by 
hydrochloric or nitric acid, as, for example, calomel and ignited 
ferric oxide, are sufficiently altered by the free chlorine of aqua 
regia to become soluble. 

Analysis of Insoluble Substances. 

If the substance is insoluble in water and acids, it is one 
or more of the following substances : — Sand and certain sili- 
cates, such as pipeclay and other clays; fluor-spar ; cryolite, 
NagAlFg ; barium, strontium, and possibly calcium sulphates ; 
tinstone ; antimonic oxide ; glass ; felspar (aluminium and 
alkali-metal silicates) ; silver chloride, bromide, or iodide ; 
lead sulphate. It may also be or contain carbon or carbon- 
aceous matter, in which case it is black and combustible,, 
burning entirely or partially away when heated in the air — 
or it may be or contain sulphur, in which case sulphurous 
anhydride is evolved, detected by its odor, when the substance 
is heated in air. A drop of solution of ammonium hydrosul- 
phide added to a little of the powder will at once indicate the 
presence or absence of salts of such metals as lead and silver. 
For the other substances, proceed according to the following 
(Bloxam's) method: — 

Four or five grains of the dry substance are intimately 
mixed with twice the quantity of dried sodium carbonate, and 
this mixture is well rubbed in a mortar with five times its 
weight of deflagrating flux (1 of finely powdered charcoal to 



INSOLUBLE SUBSTANCES. 361 

6 of nitre). The resulting powder is placed in a thin porce- 
lain dish, or crucible, or clean iron tray, and a lighted match 
applied to the centre of the heap. Deflagration ensues, and 
decomposition of the various substances occurs, the acid 
radicals going to the alkali-metals to form salts soluble in 
water, the metallic radicals being simultaneously converted 
into carbonates or oxides. The mass is boiled in water for a 
few minutes, the mixture filtered, and the residue well washed. 
The filtrate may then be examined for acid radicals and 
aluminium, tin, etc., and the residue be dissolved in dilute 
hydrochloric acid and analyzed by the ordinary method. 

The only substance which resists this treatment is chrome 
iron-ore. 

To detect alkali in felspar, glass, or cryolite, Bloxam recom- 
mends deflagration of the powdered mineral with one part of sul- 
phur and six of barium nitrate. The mass is boiled in water, the 
mixture filtered, ammonium hydroxide and carbonate added to 
remove barium, the mixture again filtered, and the filtrate 
evaporated and examined for alkali-metals by the usual process. 

Hydroxides and Oxides. 

If no acid radical can be detected in a substance, or if the 
quantity found is obviously insufiicient to saturate the quantity 
of metallic radical present, the occurrence of oxides or hydroxides, 
or both, may be suspected. Confirmation of their presence will 
be found in the general rather than in any special behavior of the 
substances. Some hydroxides yield water when heated — in a dry 
test-tube held nearly horizontally in the flame, so that moisture 
may condense on the cool part of the tube. Some oxides yield 
oxygen — detected by heating in a test-tube, and inserting the 
incandescent end of a strip of wood. Soluble hydroxides cause 
abundant evolution of ammonia when heated with solution of 
ammonium chloride.' Soluble hydroxides also give characteristic 
precipitates with the various metallic solutions. Hydroxides and 
oxides insoluble in water, not only neutralize much nitric acid, or 
acetic acid, but are thereby converted into salts soluble in ^svater. 
Most oxides and hydroxides have a characteristic appearance. In 
short, some one or more properties of an oxide or a hydroxide 
will generally betray its presence to the student who not only has 
knowledge respecting chemical substances, but has cultivated the 
faculties of observation and perception. 

'Eed litmus-paper placed over the mouth of a test-tube iu which ammo- 
nium chloride solution alone is being boiled turns blue, but phenol- 
■pthalein paper is not affected. 



362 QUALITATIVE ANALYSIS. 

Fractional Operations. 

Not only is the common process of sifting (p. 355) through 
sieves of varying degrees of fineness a useful fractional operation 
or separatory adjunct in analytical as in other work, but also 
fractional elutriation (p. 134), fractional solution of a mixed mass 
by lixiviation (p. 89) of the substance with successive small quan- 
tities of solvents, and fractional jorec«piifa^io;i with filtration after 
each addition of successive small quantities of a precipitant are 
often valuable aids. Fractional distillation {see p. 420) is often 
very useful, fractional sublimation (p. 96) and fractional crystalli- 
zation (p. 82) occasionally, fractional fusion less often. 



QUESTIONS AND EXEECISES. 



Describe the preliminary treatment to which a salt may be subjected 
prior to systematic analysis. — Mention substances which might be recog- 
nized by smell.— Mention some salts which are heavy, and some which are 
light. — Name some substances recognizable by their color. — What infer- 
ence may be drawn from the appearance of steam when dry substances 
are heated?— Why do certain crystals decrepitate?— If a powder sublimes 
on being heated, to what classes of compounds may it belong ? — When 
heat causes charring, what conclusion is drawn ? — No change occurring 
by heat, what substances cannot be present? — Give examples of salts 
which are identified by their behavior with concentrated sulphuric acid, 
and by their comportment in the blow-pipe flame, with or without borax 
or microcosmic salt. — What are the solvents usually employed in endeav- 
oring to obtain a substance in a state of solution, and what is the order 
of their application?— Name a few salts which may be present in an 
aqueous solution. — Menti<m some common compounds insoluble in water, 
but soluble in hydrochloric acid.— What substances are only attacked by 
nitric acid or nitro-hydrochloric acid ? — At what stage of analysis do 
arsenites and arsenates show themselves ? — Sketch a method for the com- 
plete analysis of a liquid suspected to be an aqueous solution of neutral 
salts. — How can alkaline-eartb-metal phosphates and oxalates and ferric 
hydroxides be separated from each other ?^B[ow would you proceed to 
analyze an alloy ? — By what process may substances insoluble in water or 
acids be analyzed ? — How would you qualitatively analyze glass? 



RECAPITULATORY AND OTHER NOTES ON SALTS. 

The molecules of a salt contain radicals which may be either 
elementaiy or compound (pp. 52, 64). 

Each radical has a definite exchangeable value, but this value 
may differ in the case of different radicals (p. 62). 

The relation to each other of the radicals in organic substances 
or salts, is apparently much more complex than the relation to 
each other of the radicals in inorganic or mineral salts. 

Berthollefs Laws. — ''When we cause two salts to react by 
means of a solvent, if, in the course of double decomposition, a 



THEORY OF SOLUTION. 



363 



new salt can be produced less soluble than those which we have 
mixed, this salt will be produced." "When we apply dry heat 
to two salts, if, by double decomposition, a new salt can be pro- 
duced more volatile than the salts previously mixed, this salt will 
be produced." 



THEORY OF SOLUTION. 



The phenomena of electrolysis have given rise to a new theory 
of solution. Formerly a salt was supposed to consist of a basic 
oxide combined with an acid oxide ; thus ** sulphate of soda " (as 
the salt now known as sodium sulphate was called) was regarded 
as Na20,S03. When a solution of sodium sulphate is electrolyzed 
{see p. 67), sodium hydroxides is formed at the negative, and sul- 
phuric acid at the positive electrode ; these substances were sup- 
posed to be produced by the union of the sodium oxide with water 
at the negative electrode and of the sulphuric anhydride with water 
at the positive electrode. To account for such phenomena a new 
theory has, however, been brought forward, according to which, 
a salt — e. g, , sodium sulphate — when dissolved in water splits up 
into an electro-positive and an electro-negative part, but these 
are now supposed to be, not the basic oxide and the acid oxide, 
but the metallic or basic radical and the acid radical. Sodium 
atoms or ions constitute the positive part, sulphate radicals or 
sulphations (SOJ the negative part ; when an electrical current is 
passed through the solution the former lose their charges of posi- 
tive electricity at the negative electrode and then act on the water, 
forming sodium hydroxide and liberating hydrogen; the sulpha- 
tions similarly lose their charges of negative electricity and then 
decompose the water at the positive electrode, forming sulphuric 
acid and liberating oxygen. When Arrhenius brought forward this 
view, a new theory of solution was much needed, for it had been 
found by careful measurements that the thermal change involved 
in the act of solution could not be entirely accounted for by the 
physical change of state. Arrhenius assumed that a salt on pass- 
ing into solution undergoes more or less complete separation into 
its ions (ionization), and that its ions act independently of each 
other, not only in electrolytic, but also in chemical processes. In 
general, we find chemical activity, in the sense of readiness to 
undergo double decomposition, to go hand in hand with electrical 
conductivity, and his explanation is that the real carriers of the 
electricity are the free ions, which, by virtue of their freedom, are 
chemically active, since they have not to be separated from each 
other before they interact 

This hypothesis of the existence of free ions in solution has 
thrown much light on the general behavior of salt sohitions, and 
has rendered possible an explanation of many hitherto inexplic- 
able phenomena. 



364 



THE PERIODIC LAW. 



THE PERIODIC LAW. 

When the elements are arranged in the order of their atomic 
weights, it is found that, starting with lithium, the chemical proper- 
ties of each successive element differ in many cases only to a rela- 
tively small degree from those of the element immediately preced- 
ing. This holds for a ''period" of (at first) seven elements, and 
then the eighth element shows a sharp change of properties 'from 
those of the seventh and a striking resemblance to those of the 
first ; the ninth resembles the second, the tenth resembles the third, 
and so on. The first two periods consist of seven elements each ; 
the subsequent ones, which are more or less complete, of seventeen 
each. In the following Table the periods are arranged in perpen- 
dicular columns, whereby kindred elements are to a large extent 
brought side by side in the same horizontal lines :— 

• Table of the Elements, arranged to illustrate the Periodic Law. 



... 






K 38.86 Eb 84.8 


Cs 131.fi 


... 


... 






Ca 39.8 Sr 86.94 


Ba 


136.4 


... 


... 






Sc 43.8 Yt 88.3 


La 


137.9 Yb 171.7 


... 






Ti 47.7 Zr 89.9 


Ce 139.2 


... Th 230.8 


... 






V 50.8 Cb 93.9 






Ta 181.6 


... 






Cr 51.7 Mo 95.3 






W 182.6 U 236.7 


... 






Mn54.6 








... 






Fe 55.5 Eu 100.9 






Os 189.6 .*."! 








M 58.3 Eh 102.2 






Ir 191.5 


... 






Co 58.56 Pd 105.7 






Ft 193.3 


Li 6.98 


Na 22.88 


Cu 63.1 Ag 107.12 






Au 195.7 


Gl 9.03 


Mg 


24.18 


Zn 64.9 Cd 111.6 






Hg 198.5 


B 10.9 


Al 


26.9 


Ga 69.5 In 113.1 






Tl 202.6 


C 11.91 Si 


28.2 


Ge 71.9 Sn 118.1 






Pb 205.35 ... 


N 13.93 


P 


30.80 As 74.4 Sb 119.3 






Bi 206.9 


15.88 


S 


31.82 


Se 78.6 I 125.9 






... 


F 18.9 


CI 


35.19 


Br 79.36 Te 126.6 






... 



It will be noticed that there are gaps in the Table suggesting 
elements yet to be discovered, or indicating uncertainty as to the 
con-ect position of a number of known elements ; also that there 
are irregularities suggesting the desirability of reconsidering some 
of the present atomic weights. Other difiiculties also occur, but 
still the regularities are so striking as to show clearly that the 
properties of the elements are in some way dependent on their 
atomic weights. 

The nature of some of the progressive relations to each other of 
the members of the first two periods are illustrated by the formulae 
of certain of their compounds when placed side by side. Where 
blanks occur, either no compound at all, or no illustrative com- 
pound, is known. 



THE PEBIODIO LAW. 



365 



Compounds with oxygen : 

GIO 
MgO 



Li^O 
NaaO 



B2O3 

Al,03 



CO, 
SiO., 






so„ — 



Compounds with hydrogen : — 

— — — CH, 

— — — SiH, 



NH3 

ph: 



OH, 
SH2 



FH 
CIH 



Compounds with chlorine :- 



LiCl 
NaCl 



GICI3 
MgCI, 



BCI3 

AlCL 



CCl, 
SiCL 



NCI3 
POL 



OCL 
SCI 



The compounds formulated above are not the whole of the oxy- 
gen, hydrogen, and chlorine compounds of the various elements, 
but are chosen to illustrate regularities as far as possible. There 
are, however, a number of irregularities in these periods, and in 
the subsequent periods irregularities become more numerous.. 

Since the position of an element in the above Table is fixed by 
its atomic weight, and since it has been found that the properties 
of an element and the character of its compounds can be foreseen 
to a certain extent from those of its neighbors in the Table, above 
and below, right and left, the general statement has been enunci- 
ated, based upon this periodic arrangement and supported by a 
great deal of evidence, that the properties of an element and the 
nature of its compounds are functions of its atomic weight. 

An inspection of the foregoing Table shows how allied elements 
are brought together in groups. Thus the halogens (with the 
exception of iodine i) all fall into one line, and the same is true of 
the groups of kindred elements, calcium, strontium and barium ; 
nitrogen, phosphorus, arsenic, and antimony ; etc. Further, each 
of the first five periods is heated by an alkali-metal. The symbols 
printed in black type are those for the small group of elements 
usually classed as non-metals, and indicate the remarkable nature 
of the position of these elements in the periodic system of classifi- 
cation. 

' It seems as if the true position of iodine in the periodic system should 
be after instead of before tellurium. The respective places assigned to 
iodine and tellurium depend, however, upon the determinations of the 
atomic weights of these elements which are considered to be the most 
reliable. 



366 ADVICE TO STUDENTS, 



ADVICE TO STUDENTS RESPECTING THE 

METHOD OF STUDYING THE FOLLOWING 

PAGES ON ORGANIC CHEMISTRY. 

Both medical and pharmaceutical students of organic chemistry 
may be divided into two classes, namely ; junior students, or those 
who, in the first instance at all events, desire to obtain only a 
general acquaintance with the subject, and senior students, or those 
who, having some general information, desire further knowledge 
of this branch of the science. To the members of each of these 
classes who use this Manual, some advice concerning the kind and 
extent of work they may hope to accomplish in this department 
of the science will perhaps be acceptable. 

Junior Students. — The whole of the following section on organic 
chemistry should be read through carefully once or twice, with 
the object, not so much of remembering all that is stated, as of 
acquiring (a) a general view of the scope of the subject, (6) a clear 
notion of the modes of classifying organic substances, and (c) an 
intelligent perception of their broad relationship to one another. 
Special attention should be given to the methods of preparing 
and testing the particular substances officially recognized in the 
Pharmacopoeia, the student of practical chemistry preparing actual 
specimens of most of these substances, as well as studying their 
analytical reactions and testing for impurities in them. He should 
prepare small quantities of chloroform, iodoform, spirit of nitrous 
ether, acetic ether, and a volatile oil ; should extract gum from a 
gum-resin, purify some benzene, test aloin, and examine methy- 
lated spirit of methyl alcohol ; prepare some alcohol by fermenta- 
tion, concentrating the product until it will burn ; make ether ; 
convert amyl alcohol into valeric acid ; test carbolic acid and gly- 
cerin ; manufacture a specimen of soap ; extract mannite from 
manna ; examine the analytical reactionsof cane and grape sugars; 
obtain starch from wheat-flour, maize-flour, and a potato, and 
examine each product with the microscope ; make dextrin, proxy- 
lin, and collodion ; prepare and test aldehyde, and try the action 
of lime on chloral hydrate ; prepare and test acetic, oxalic, and 
citric acids ; emulsify sweet and bitter almonds : prepare elaterin, 
and test jalap-resin and salicin ; extract morphine or quinine, or 
both, and perform the tests for the chief alkaloids of opium, cin- 
chona, and nux vomica ; test albumin and pepsin. Having gone 
through these operations, he should read again through the whole 
section. 



ADVICE TO STUDENTS. 367 

Senior Students, having done all that junior students are, in the 
previous paragraph, advised to do, should thoughtfully study every 
page, reading what one other author, at least, has to say on each sub- 
ject. More especially they should actually prepare, or test, or other- 
wise experiment with, one or more typical members of most of the 
series, or sub-series, of organic substances. For example, they 
should prepare the hydrocarbon methane (from sodium acetate), con- 
vert it into a haloid derivative (by one of the given methods), trans- 
form this into the alcohol (by the agency of silver oxide and water), 
and this again into the acid (by oxidation). The preparation of ace- 
tylene, and ethylene, and some of their derivatives, should be tried; 
the differences between turpentine and petroleum spirit should be 
experimentally proved ; nitro-benzene should be made, this be con- 
verted into aniline, and this again into *' mauve" ; aloin should be 
prepared ; methyl alcohol be extracted from crude wood spirit, and 
absolute alcohol be obtained from ''alcohol (92.3 percent.)" ; 
alcohol and acetic acid should be regenerated from the acetic ether 
previously prepared (by ebullition with a concentrated aqueous 
solution of potassium hydroxide) ; ethyl iodide or bromide and per- 
haps zinc-ethyl be made ; glycol be prepared and then oxidized ; 
glycerin be examined ; starch be converted into dextrin and into 
sugar ; malt extract be examined for diastase ; trinitrocellulin be 
made ; acetaldehyde be fully examined and aldehyde-ammonia 
prepared ; lactic acid be made ; benzoic and salicylic acids and 
aldehydes be obtained ; natural urea be extracted and an artificial 
urea made ; the glucosides be examined ; and one or two artificial 
alkaloids be prepared ; etc. Melting-points and boiling-points of 
pure substances should be taken ; and fractional distillation should 
be applied either to acetic acid with a view to separate glacid acid 
on the one hand from water or weak aqueous acid on the other, to 
mixed alcohol and water with the object of attempting their 
re-separation as far as possible, or to some such mixture. Especi- 
ally must the operations of quantitative analysis of organic com- 
pounds, in due time, be fully and thoroughly performed. 

Other Students. — Students who have no occasion to apportion 
their periods of study in the manner contemplated in the previous 
paragraphs are recommended to go through the succeeding sections 
as they have gone through the foregoing, namely, page by page. 



ORGANIC CHEMISTRY.' 

Introduction. 

With the exception of alcohol, some acids and their salts, 
and a few other substances, the large number of compounds 
which have hitherto engaged the student's notice in this 
Manual have been of mineral origin. But the two other 
kingdoms of Nature, the animal and vegetable, furnish still 
larger numbers of definite compounds. We shall now pro- 
ceed to the consideration of these, the latter chiefly. 

In its original signification what was termed Organic 
Chemistry {opya-Mv^^ organon, an organ) embraced the chemistry 
of those substances which were known only as products of the 
vital processes which take place within the tissue of plants 
and of animals ; and, further, the chemistry of the various 
products derived from these substances, or from the tissues 
themselves, by subsequent treatment in the laboratory. The 
separate classification and consideration of these substances 
formerly seemed expedient in view of the fact that none of 
them could then be obtained by the ordinary operations of 
the chemical laboratory, starting from non-organized materials. 
The term " organic " as originally applied to any substance 
was thus intimately associated with the view that organized 
matter — living matter, or matter which had at one time 
formed part of a living plant or animal — was necessary for 
its production. Methods are now known, however, whereby 
a considerable number of substances which are identical in 
every respect with known products of animal or plant life 
(or with derivatives from these) can be prepared in the labo- 
ratory "artificially," as it is often termed, from purely inor- 
ganic materials. 

^ Students will find that in taking up the subject of organic chem- 
istry they are not departing from the method of study hitherto pursued. 
Hitherto they have concentrated attention on the chief elements, one at 
a time ; they are now about to investigate the compounds of one of those 
elements which possesses a greater range of combining powers than any 
other that has been examined. Organic chemistry is the chemistry of the 
element carbon. 

368 



INTRODUCTION. 369 

Organic chemistry has been defined in more recent times 
as the chemistry of the compounds of carbon. There does 
not, however, now seem to be any good reason for classing as 
organic, the oxygen compounds and some other relatively 
simple compounds of carbon, including many of the naturally 
occurring mineral carbonates ; more particularly as these 
must, for the sake of completeness, be dealt with under the 
heading of inorganic chemistry. It is thus impossible to fix 
the bounds of inorganic and of organic chemistry respectively, 
unless an arbitrary line is drawn, which shall mark a distinc- 
tion that is wholly artificial, and is not founded upon any real 
difference in the general nature of the facts and principles 
treated of under the two headings. There is, in short, but 
one science of chemistry, and the separate consideration of 
the chemistry of the majority of the compounds of carbon is, 
to a large extent, a matter of convenience only. The very 
great number of the compounds of carbon and the complexity 
of many of them, together with the general readiness which 
they usually exhibit to enter into new combinations, may be 
mentioned as among the reasons for their separate study. 
The one fundamental fact concerning every so-called organic 
compound is, that it contains carbon as one of its constituents, 
combined with one or more other elements ; but, as we have 
already seen, every compound of carbon is not an organic com- 
pound in any sense which it is convenient strictly to define. 
Of course, so old and historically interesting a term as organic 
chemistry will continue to be used ; and there is no objection 
to such use, provided students remember that when the term is 
used, it is only conventionally and not etymologically accurate. 

It will be unnecessary to discuss again in what follows the 
chemistry of those compounds of carbon which have already 
been treated of in earlier parts of the Manual. 

As instances of the formation, from purely inorganic 
materials (or from products obtainable from inorganic 
materials), of compounds which are generally classed as 
organic, the following may be mentioned ; — 

(1) The formation of acetylene, C2H2, by passing electric 
sparks from carbon terminals in an atmosphere of hydrogen ; 
and by the action of water on calcium carbide. 

(2) The formation of potassium cyanide, KCN, by passing 
nitrogen over a strongly-heated mixture of potassium and 
carbon, or of potassium carbonate and carbon heated to the 
temperature at which potassium is liberated (p. 72). 

24 



,M 






% 



X 






70 



ORGANIC CHEMISTRY. 






(3) The formatiou of marsh gas, CH^, by passing a mixture 
of hydrogen sulphide and vapor or carbon bisulphide over 
red-hot copper. 

(4) The formation of urea, C0(NH2),, by the action of 
ammonia on carbonyl chloride (phosgen) ; and by evaporating 
to dryness a solution of ammonium cyanate. 

5) The formation of potassium formate, KHCOg, by the 
ction of carbonic oxide on potassium hydroxide. 



Elements which enter into the composition of organic Substances. — 
The elements which, beside carbon, are of the greatest impor- 
tance from their entering most frequently into the composition of 
organic substances are hydrogen, oxygen, and nitrogen. All the 
naturally occurring organic substances contain carbon and hydro- 
gen, associated almost always with oxygen, and often with nitro- 
gen; some of them also contain sulphur or phosphorus or both, 
in small quantity. Among artificially prepared organic sub- 
stances, colnpounds have been obtained containing almost any of 
the other known elements. 

Detection of the various elements present in Organic Substances. — 
It is not intended here to give any detailed account of the analysis 
of organic substances, but the general principles and a few im- 
portant methods may advantageously be outlined. 

In order to demonstrate the presence of combined carbon and 
hydrogen in any substance, it is usual to burn a small quantity 
of the substance in a current of pure dry air or oxygen in a hard- 
glass tube closely packed for a part of its length with cupric 
oxide' which is kept red-hot throughout the operation. The cur- 
rent of air or oxygen enters at one end of the tube and the 
gaseous products of combustion pass out at the other. During 
the process the carbon and hydrogen of the substance are com- 
pletely oxidized — the former into carbonic anhydride and the 
latter into water — and the presence of the two elements is indi- 
cated by the formation of these respective products. This process 
can be made a method of quantitative analysis, since, by collecting 
and determining the weights of the two products obtainable from 
a known weight of the organic substance, data are obtained from 
which the proportions by weight in which the two elements are 
present in the substance can be calculated. 

The presence of nitrogen in an organic substance is detected by 
strongly heating a few grains of the substance in a test-tube with 
a small piece of metallic sodium, grinding up the fused mass with 
water, filtering, and examining the solution for the presence of a 
dissolved cyanide. In the process the nitrogen of the substance, 
along with some of the carbon, combines with the sodium to form 
sodium cyanide, NaCX; and the observation that a cyanide has 
been formed is a proof of the presence of nitrogen in the sub- 



INTRODUCTION. 



371 



stance. Part or the whole of the nitrogen of some (but not of all) 
organic substances is evolved as ammonia when the substance is 
moderately heated in a test-tube with soda-lime. ^ The quantita- 
tive determination of nitrogen is effected by various methods, but 
the only one which need be mentioned here is analogous to that 
employed for the determination of carbon and of hydrogen. A 
w^eighed quantity of the substance is heated in a slow current of 
carbonic anhydride in a glass- tube containing cupric oxide which 
is heated red-hot. The nitrogen is liberated either as such, or in 
the form of gaseous oxide of nitrogen. Before emerging from the 
tube the mixture of gases passes over a quantity of red-hot copper 
wire-gauze, tightly packed. The latter retains any free oxygen 
by combining with it to form cupric oxide, and also decomposes 
the oxides of nitrogen, similarly retaining the oxygen of these 
while the liberated nitrogen passes on. The carbonic anhydride, 
water vapor, and nitrogen which emerge are passed into a gradu- 
ated tube containing a concentrated solution of potassium hydrox- 
ide. The carbonic anhydride is here absorbed forming potassium 
carbonate, the water vapor condenses to form liquid water, and 
the pure nitrogen is collected and its volume is measured. From 
the observed volume, under the conditions of temperature and of 
pressure which has also been noted, the weight of the evolved nitro- 
gen can be calculated. 

The presence of oxygen in a non- volatile organic substance can 
usually be detected by simply heating the dry substance in an 
atmosphere free from oxygen, and observing the formation of 
water. The oxygen necessary for the production of water, in 
such a case, must have been present in the substance under ex- 
amination. The direct quantitative determination of oxygen 
presents considerable experimental difficulties, and no satisfactory 
methodA^r making this determination has come into general use. 
It is usual in actual practice to determine the quantities of all the 
other elements present in a given weight of the substance and 
then to regard the remainder as the quantity of oxygen. 

In order to detect sulphur or phosphorus in an organic sub- 
stance, the latter is, in most cases, first oxidized by some suitable 
process, and the oxidation products are then examined for the 
presence of sulphuric or phosphoric acid. The quantitative deter- 
mination of these elements ^so usually requires oxidation as a 
preliminary. ^ 

The detection and quantitative determination in organic sub- 
stances of other elements, such as chlorine, bromine, iodine, 
metals, etc., require in general the oxidation of the substance or 
the decomposition of it by some other process, and the subsequent 
examination of the products of such operations by the methods 



^The product obtained by slacking quicklime with a solution of sodium 
hydroxide. 



372 ORGANIC CHEMISTRY. 

of qualitative and quantitative analysis applicable to inorganic 
substances. 

General effects of Heat upon Organic Substances. — The effects 
produced by heating various organic substances vary greatly in 
the cases of different compounds. We shall briefly consider 
the general effects (1) when organic substances are heated by 
themselves, that is, out of contact with anything more than small 
quantities of air; and (2) when they are heated with free access 
of air. 

(1) Solid organic substances when heated may simply become 
, liquid, and the liquid so produced may, on being further suffi- 
ciently heated, boil and be completely volatilized without under- 
going any decomposition. Glacial acetic acid and acetamide are 
examples of such substances. Other solid substances may simil- 
arly become liquid, but the liquid on further heating may decom- 

• pose before the temperature of volatilization has been reached. 
This is the case with cane sugar and with urea. Other solid sub- 
stances again, such as starch and cellulose, cannot be liquefied by 
heating them because the temperature at which decomposition 
takes 2)lace lies below the temperature of liquefaction. Substances 
belonging to these last two classes very commonly yield on 
decomposition by heat a quantity of volatile products (some of 
which are gaseous and others liquid at ordinary temperatures) and 
leave behind in the vessel in which the decomposition has taken 
place, a highly carbonaceous, non- volatile black residue or char- 
coal. Charcoal suitable for special purposes is often prepared by 
thus heating starch, sugar, cellulose, etc. When non-volatile 
organic substances are subjected to this treatment the process is 
called dry or destructive distiUation. Such processes are carried 
out on a very large scale with wood, with coal, and withjAifferent 
kinds of shale, and form a part of several important m^ifactur- 

• ing industries. 

' — t)f organic substances which are liquid at ordinary tempera- 
tures, a very large number, such as common alcohol and ether, 
are capable of volatilization without decomposition, while others, 
such as glycerin, decompose at temperatures below their boiling 
points. "Substances which belong to this latter class cannot 
therefore be distilled without decomposition, at least under ordi- 
nary pressures. In some instates it is found possible, by 
diminishing the pressure inside the distilling apparatus, to lower 
the boiling point of the liquid to a temperature below that at 
which decomposition takes place and so to ensure its distilling 
undecomposed. 

Organic substance which are gases at ordinary temperatures, 
and the vapors of organic substances which are solids or liquids 
under these circumstances but which volatilize undecomyosed, 
may be exposed to the action of high temperatures by ^owly 



INTRODUCTION. 



373 



passing them through heated tubes. Under this treatment some 
decompose readily, while others do not undergo any, or at least 
any considerable, change. A method frequently made use of for 
very rapidly heating a vapor, is that employed in the manufacture 
of " oil gas " from paraffin oil. The liquid oil is allowed to drop 
on a red-hot metal or brick surface, when the vapor which is at 
first produced becomes very strongly heated before it has time to 
diffuse away from the hot surface. In this way the paraffin oil is 
decomposed, yielding some coke and combustrW^MjI^^dMph do 
not become liquid again at ordinary tempe^^ilrtBiP!iPW^i*ati on 
is technically called ''cracking" the^^^Mpcar1)oiLs of whiclj the 
paraffin oil is composed. if^F i^^^^^ 

(2) When organic substances are strohgly heatedpi^^itable 
forms of apparatus with free access of air^^yJbgy^gually undergo 
complete oxidation, so far, at least, as theiiPSarbon and hydrogen 
are concerned. These elements become converted into carbonic 
anhydride and water respectively. When a salt of any of those 
organic acids which contain carbon, hydrogen, and oxygen only, 
is subjected to this treatment, the carbon may either be com- 
pletely driven off as carbonic anhydride, or a part may remain 
combined in the form of a carbonate. The metal of the salt 
remain behind either as metal (silver, platinum, etc.) or as 
(lead oxide, zinc oxide, ferric oxide, etc. ) or as carbonate (p' 
slum carbonate, barium carbonate, etc.). 

DistiUatio7i. — The purification of organic substances is often 
effected by distillation, as, for example, when a volatile substance 
is impure from the presence of any non-volatile admixture. The 
separation of alcohol by distillation from the non-volatile constit- 
uents present in the liquid of the fermenting tun is an instance of 
this kind (p. 420). 

A mixture of two or more liquids (all of them volatile, but of 
different boiling points when pure and unmixed) may be more or 
less completely separated by ^^ fractional distWation "—that is, by 
separately collecting the portions of the distillate ("fractions" as 
they are called) which distil at different temperatures, or rather, 
within certain intervals of temperature. Such fractions do not, 
as a rule, consist entirely of one single liquid, but generally con- 
tain some of the other volatile substances present in the original 
mixture. By subjecting each original fraction to a second frac- 
tional distillation, and systematically carrying out tiie same process 
on succeeding fractions for several times, fractions of almost con- 
stant boiling point, and composed almost entirely of one liquid 
can in many instances be obtained ; but in some cases nothing 
more than a very partial separation can be effected. Thus from 
a mixture of alcohol and water it is not possible by distilhition 
alone, to obtain alcohol containing less than about 5 percent, 
of water. 



t ro^^^ 



374 ORGANIC CHEMISTRY. 

Classes of Organic Compoumh. — The majority of organic com- 
pounds are conveniently grouped into two main classes, which are 
known as the Fatty (or Aliphatic), and the Aromatic classes 
respectively. When these names were first employed, only a 
comparatively limited number of organic compounds were known. 
The natural fats gave rise to a number of representatives of the 
first-class, which may all be regarded as derivatives of methane, 
CH^ ; a considerable number of representatives of the second 
class, which may be regarded as derivatives of benzene, CgHg, are 
more or less arom^^;y£ substances, such as some of the essential 
oils, etc. Th^i^ Oi J^^tty and aromatic are of historical interest, 
but although an comm(» use, they cannot now be looked upon as 
very approprmte. Injiealing with the- fatty or aliphatic and the 
benzene or arxl||||||yj[|l^ompounds, these two classes will only be 
considered separately in so far as a moderately systematic treat- 
ment may seem to require. 

Constitution or Structure of Organic Compounds. — The problem 
of the relations to one another of the various atoms which com- 
pose a molecule, is one which early attracted the interest and 
attention of chemists ; and it is one for the solution of which 
-Tftaicrials have been accumulated slowly and laboriously from the 
syniietical and analytical investigation first of the simpler and 
aft^ward of the more complex chemical compounds, inorganic 
and organic. How to recognize the presence of certain groups of 
atoms, or radicals, in the molecules of chemical substances, and 
how to find out the position of these groups in the molecules is 
often a most difficult and yet a most fascinating task for the 
enthusiast and skilled experimentalist in chemistry ; and how to 
so marshal these groups (drawn perhaps from several different 
sources, and obtainable only in a state of combination) that he 
shall produce by art the compound originally only ftirnished by 
nature, is still more difficult, but also more fascinating. 
More fascinating firstly, because it will ftirnish proof that 
his synthetical work was sound; secondly, because by artificially 
and perhaps cheaply producing a rare color, a rare perftune, a rare 
flavor, or a previously costly medicine, he may become a bene- 
factor to his fellow-man; and thirdly, because he may gain the 
honor of unveiling for all time one more of the truths of nature. 

In practically attacking the problem of the constitution of a 
compound, the' chemist proceeds to note whether the substance is 
acid, alkaline, or neutral ; to act on it with a base of known con- 
stitution if it is an acid, or Avith an acid of known constitution if 
it is a base, and to analyze the produced salts ; to oxidize it ; to 
deoxidize it ; to heat it ; to electrolyze it ; to chlorinate it ; to 
remove or add hydroxyl (OH), carbonyl (CO), etc. ; to substitute 
hydrogen by a compound radical, and vice versa ; and, generally, 
to perform many such operations, in the hope that the lines of 
chemical cleavage in the molecule will be detected, the essential 



INTRODUCTION. 



375 



groupings of atoms in the molecul,e be discovered, and even the 
positions of atoms or groups of atoms in relation to each other be 
reasonably inferred. Briefly, similarity in properties implies 
similarity in constitution or structure. Per contra, similarity in 
structure being reasonably implied, reference to properties shows 
whether or not the reason is on the right track toward truth in 
the matter of constitution or structure, the advance toward error 
being prevented and toward truth being maintained whatever be 
the result of the reference, new truths not infrequently being 
unveiled. Thus, by the way, in chemistry, do fact and theory 
ever discharge their obligations to each other. , 

Notation of Organic Compounds. — In order that we may convey 
to one another our conclusions respecting the constitution of 
organic compounds, notation has to be carried somewhat farther 
in organic than is as a rule necessary in inorganic chemistry. The 
relative positions of atoms and groups of atoms in a molecule may 
be indicated by placing the symbolic letters above or beneath one 
another as well as on one line, and the quantivalence of atoms, as 
well as the ways in which we conclude they are linked in the 
molecule, may be indicated by lines ( — = eee) or dots (. : j) 
either completely or only partially employed throughout the for- 
mula ; each dot or line or ''link," or ''bond," representing the 
supposed condition of union between two neighboring atoms or 
radicals. Eormulse which, by the aid of such dots or lines, pur- 
port to represent the relative positions of the atoms and groups of 
atoms in molecules (^. e., to represent the constitution or structure 
of the molecules) are called constitutional or structural for mulce. 
Many examples of such formulae will be met with in the succeed- 
ing pages of this Manual. When structural formulae are written 
in the most extended form, so as to represent by the aid of lines 
the way in which every atom in a molecule is united to its adja- 
cent atoms, the resulting formulae are often called graphic formulae. 



QUESTIONS AND EXERCISES. 

What do you understand by organic chemistry ?— Give methods of 
ascertaining the presence of carbon, hydrogen, and nitrogen in organic 
compounds. — Give an outline of the methods by which the quantities of 
carbon, hydrogen, oxygen, and nitrogen are determined in organic com- 
pounds.— What is meant by "fractional" distillation ?— Name two of the 
chief classes into which organic compounds are divided. — How is the con- 
stitution of an organic compound ascertained ? — What do you understand 
by constitutional or structural formulae?— What are graphic formulae? 



HYDROCARBONS. 

Compounds known as hydrocarbons contain the elements 
hydrogen and carbon only, and are exceedingly numerous. A 



376 ORGANIC CHEMISTRY. 

very large number of the known hydrocarbons belong to the fatty 
class, three of the chief groups being the ParaflSn, the Olefine, and 
the Acetylene series. 

THE PARAFFIN SERIES OF HYDROCARBONS. 

Of all the known hydrocarbons, the simplest in composition is 
methane or marsh gas, which is the first member of the series 
called Paraffins. In this series of hydrocarbons (and in it alone) 
the total combining capacity of each carbon atom is satisfied in 
such a manner (either by linkage with hydrogen atoms, or with 
other carbon atoms, or, as is almost always the case, by linkage, 
partly with hydrogen atoms and partly with other carbon atoms) 
that the members of the series are not capable of entering into 
direct union with chlorine or bromine, so as to form additional 
compounds. Hence the series of paraffins is often called the series 
of saturated hydrocarbons. Methane is the only hydrocarbon 
which has the total combining capacity of its carbon satisfied by 
linkage with hydrogen atoms. Its composition is represented by 
the formula CH^ 
H 

I 
o^—Q—R. 

H 

If we suppose one hydrogen atom of methane to be removed and 
its place to be taken by the group— CH3 (which is called methyl), 
we get the composition of the next simplest paraffin, ethane, 
CgHg. There is no reason to suppose that any one of the four 
hydrogen atoms of methane differs in the least from any of the 
others in the way in which it is related to the carbon atom and to 
the other three 'hydrogen atoms. Thus on considering in the 
H 

graphic formula H— C— H, the relations of any particular 

H ' . . 

hydrogen atom, we see that it is linked to a carbon atom which m 
turn is linked to three other hydrogen atoms. Accordingly it is 
immaterial which of the four hydrogen atoms we suppose to be 
replaced bv the methvl group, because, if the relations of all four 
are similar, there would in any case result the substance ethane, 

H H 
H— C— C— H. Ethane is also a paraffin (the second of the 



PARAFFINS. 



377 



series) and contains two carbon atoms, each of which is linked 
one-fourth to carbon and three-fourths to hydrogen. 

But just as in methane any one of the four hydrogen atoms is 
related to the single carbon atom in the same way as any other, 
so in ethane, any one of the six hydrogen atoms is related to one 
of the carbon atoms in the same way as any other is. 

Thus on considering, in the graphic formula for ethane just 
given, the relations of any one of the six hydrogen atoms, we see 
that it is linked to a carbon atom which is in turn linked to two 
other hydrogen atoms and to the group — CHg. The relation of 
each hydrogen atom to what is called the "carbon nucleus," in this 
case C — C, is the same. Hence if we suppose one hydrogen atom 
of ethane to be removed and its place to be taken by the group — 
CH3, it is immaterial in this case also which of the hydrogen atoms 
we suppose to be thus replaced. The resulting compound is pro- 
pane, C3H8, the third hydrocarbon of the paraffin series. Consid- 

H H H 

1 I I 

eration of the graphic formula of this substance, H — C — C — C — H, 

I I ! 
H H H 

reveals the fact, however, that all of the hydrogen atoms are no 
longer similarly related to the carbon nucleus, C— C — C. Each 
hydrogen atom is linked to a carbon atom as before, but while six 
of the hydrogen atoms are linked to the two end carbon atoms, 
which besides are one-fourth linked to carbon, the two remaining 
hydrogen atoms are linked to the central carbon atom which is 
one-half linked to carbon. The eight hydrogen atoms in propane 
are thus divisible into two groups, consisting of six and of two 
respectively, according to the position in the carbon nucleus of the 
carbon atoms to which they are linked. If then, we suppose one 
hydrogen atom of propane to be removed, and its place to be taken 
by the group — CH3 it may not any longer be immaterial which 
atom we suppose to be thus replaced. The resulting compound 
will in any case have the composition, C^H^^,, but it is evident that 
two different arrangements of these atoms are possible as indicated 
by the formulae : — 

H H H H H H H 

(1) H— C— C— C-C— H and (2) H— C— C— C— H. The 

I I I I III 

H H H H H CH3 H 

mula (1) would represent the arrangement in the case of 

replacement of an end hydrogen atom of propane by — CH.. : 

formula (2) that in the case of the similar replacement of a central 

hydrogen atom. As a matter of fact, two (and only two) paraffins 

are known, both with molecular weight corresponding to the 

formula, C^H^^j, but differing from each other in properties. The 



for- 



the 
the 



378 ORGANIC CHEMISTRY. 

formula (1) is assumed to represent one of these two compounds 
which is called normal butane, and the formula (2) to represent 
the other which is called isobutane. 

Although it is beyond our present intention to follow much 
further the possible varieties in the constitution of the compounds 
which we may regard as derived from 'Mower" paraffins (/. e., 
paraffins containing in their molecules a smaller number of carbon 
atoms) by the replacement in these of different hydrogen atoms hj 
the methyl group ; it may be well to proceed here one step further 
in this direction in the cases of normal butane and isobutane, both 
of which we may regard as derived, by this kind of replacement, 
from propane. 

Thus on considering the hydrogen atoms of normal butane (for- 
mula (1) above) it is seen that six of them (the two end sets of 
three each) are linked to two carbon atoms which in turn are one- 
fourth linked to carbon and are both related in the same way to 
the carbon nucleus, while the remaining four (the two central sets 
of two each) are linked to carbon atoms which in turn are one- 
half linked to carbon and are both related in the same way to the 
carbon nucleus, but that any one of the six has got the same kind 
of relations to the remaining atoms in the molecule as any other 
of the six has, and that any one of the four has likewise got the 
same kind of relations to the remaining atoms in the molecule as 
any other of the four has. From normal butane then, if we sup- 
pose one hydrogen atom to be replaced by the methyl group, it is 
conceivable that two different substances might be derived, one of 
which would be represented by the formula — 

H H H H H 

H — C— C— C— C— C — H, and the other by the formula 

I I I I I 
H H H H H 

HHHH HHHH 

H— C— C— C— C— H or H— C— C— C— C— H. 

HCH3H H H HCH,H 

But on considering the hydrogen atoms of isobutane (formula 
(2) above) it is seen that nine of them (three sets of three each) 
are linked to three carbon atoms which in turn are one-fourth 
linked to carbon and are all related in the same way to the 
carbon nucleus, while the remaining one is linked to a carbon 
atom which in turn is three-fourths linked to carbon and differs 
from all the others in its relation to the carbon nucleus. The 
relations to the remaining atoms in the molecule, of any one of 
the series of nine hydrogen atoms are of exactly the same kind as 



PARAFFINS. 



379 



those of any other of them, and the relations of each of them are 
different from those of the single hydrogen atom. Here again 
then, if we suppose one hydrogen atom of isobutane to be replaced 
by the methyl group, it is conceivable that two different sub- 
stances might be derived, of which one would be represented by 
the formula — 



H- 



HHHH HHHH HHH 

I I I I MM III 

-C— C— C— C— H or H— O-C— C— C— H or H— C— C— C— H 



I I I I 
HCH,H H 



I II I 
H HCH3H 



I I I 
H I H 
H— C— H 

I 
H— C— H 

I 
H 



and the other by the formula 



H 

H I H 

H C H 
H— C— C— C— H. 

H I H 
H 

But comparison of the formula given for the second of the con- 
ceivable derivatives from normal butane with that given for the 
first of the conceivable derivatives from isobutane shows that these 
two are identical, and that therefore there are theoretically only 
three paraffins of the formula C^H^^ derivable from the two butanes 
by the replacement of one hydrogen atom by the group — CH3. 
As a matter of fact three paraffins (and only three) are known all 
with molecular weight corresponding to this formula. They are 
called pentanes and they differ very considerably from one another 
in their properties. 

Isomerism, Polymerism, Metamerism. — The occurrence of two 
or more substances possessing the same centesimal composition but 
differing in properties, as exemplified in the cases of a number of 
the paraffins mentioned in the foregoing paragraphs, is very fre- 
quently met with, especially in organic chemistry. Substances 
which stand in this relationship to each other are termed isomeric 
(from "loo-, isos, equal, and juepog, meros, part) ; and their condition 
is spoken of as one of isomerism. There is sometimes good reason 
for doubling or otherwise nuiltiplying the formula of one of two 
isomers, isomerides, or isomeric substances. Thus a molecule of 
ethylene (olefiant gas), one of the chief illuminating constituents 
of coal gas, is represented by the formula C2H^, while a molecule 
of butylene, a hydrocarbon having the same percentage composi- 
tion as olefiant gas, is represented by the formula C^Hg, because 
butylene in the state of gas is specifically twice as heavy as ethy- 



380 ORGANIC CHEMISTRY. 

lene, and must contain, therefore, in each molecule, twice as 
many atoms, since (Avogadro) equal volumes of the substances in 
the gaseous state and under the same conditions contain equal 
numbers of molecules ; its formula is, consequently, fixed in con- 
formity with these facts. This variety of isomerism is termed 
polymerism (from tto/.vq, polhs, many or much, and utpoq, part). 
Formaldehyde, CH2O, acetic acid, C2H^02, and lactic acid, C.^HgOg, 
furnish another group illustrative of polymerism. Metastannic 
acid {see p. 195) is a polymeric variety {polymer or poly metide) of 
stannic acid. An example of another variety of isomerism is seen 
in the case of ammonium cyanate and urea, substances already 
alluded to in connection with cyanic acid. These and several 
other pairs of chemical substances have dissimilar properties, yet 
are similar in the centesimal proportion of their elements, and we 
cannot avoid the conclusion that each molecule possesses the same 
number of atoms. But the reactions of these substances indicate 
their probable constitution ; and this is represented in their for- 
muliE by the disposition of the symbols. Thus ammonium cyanate 
is represented by the formula NH^CNO, urea by CO(NH2)2. Such 
substances are termed matameric (from jierd, meta, a preposition 
denoting change, and juepoc;), and their condition spoken of as one 
of metamerism. Ethyl acetate (p. 403) is metameric with butyric 
acid (p. 453) ; they have the same percentage composition and the 
same vapor density and each might be represented by the formula 
C^Hg02, ; but their properties warrant us in assuming that their 
atoms occupy different positions in the two molecules — justify us 
in writing CHg.COOC.^Hj as the formula for a molecule of ethyl ace- 
tate, and G^H^.COOH as the formula for a molecule of butvric 
acid. Methyl acetate, CH3.COOCH3, propionic acid, G.H^.COOH, 
and ethyl formate, H.COOCgHj, are isomers of the metameric 
variety, or mefamers or matemerides ; also quinine and quinidine, 
cinchonine and cinchonidine, many of the volatile oils, etc. 

Homologous Series. — In the consideration, so far, of the series of 
paraffins, we have seen that, starting from the first member, 
methane, each succeeding member of the series differs from the 
one which immediately precedes it by containing the group — CH3 
in the place of an atom of hydrogen ; or, in other words, by the 
common difference of one atom of carbon and two atoms of hydro- 
gen (CH2). Many other series of substances besides the paraffins 
are known in which the successive members differ from one another 
by CH2, or a multiple of CHo. Such series are called homologous 
(from onoc, homos, the same, and 7.6yog, logos, proportion). The 
''higher" members of the paraffin series (i. e., those containing 
in their molecules more than one atom of carbon) are called homo- 
logues of methane. 

General formulae for homologous series. — It is often convenient 
(and it is always possible) to represent the general composition of 
the members of any homologous series of compounds by means of 



PARAFFINS. 381 

a formula. In the case of the paraffins the general formula is 
usually written C„H2n+2, where n represents the number of carbon 
atoms in a molecule of the compound. This formula shows that 
whatever number of carbon atoms a molecule of the paraffin con- 
tains, it contains twice that number of hydrogen atoms and two 
hydrogen atoms besides. The general formulae for some other 
homologous series will be given later in their respective places. 

Normal Paraffins. — The term normal is applied to those paraffins 
in which the carbon nucleus is capable of being represented as 
consisting of carbon atoms so linked together as to form a single 
"chain" without any *' side-branches " (or "side-chains") ; for 
example, C — C as in ethane, C — C — C as in propane, C — C — C — C 
as in normal butane, C — C — C — C — C as in normal pentane. It 
will be observed that in these "chains" the carbon atoms are 
represented as either one-fourth or one-half linked to other carbon 
atoms, but never more than this. Contrast these straight ' ' chains ' ' 
with C — C — C, the carbon nucleus of isobutane, and with 

I c 

c I 

C — C — C — C and C — C — C, those of isopentane and of tetra- 

I I 

C C 

methyl methane respectively, in the first two of which one carbon 
atom of each is represented as three-fourths, while in the last, one 
carbon atom is represented as wholly linked to other carbon atoms. 
Carbon atoms which may thus be distinguished in the carbon 
nucleus by the different proportion of their combining capacity 
which is satisfied by linkage wdth other carbon atoms, are 
designed as primary, secondary, tertiary, or quaternary, accord- 
ing as one-fourth, one-half, three- fourths, or the whole of that 
combining capacity is so satisfied. 

In connection with these designations of carbon atoms it is not 
unimportant to note that the carbon atom in methane is not linked 
to other carbon atoms at all but to hydrogen atoms exclusively; 
and that, with respect to this peculiarity of its carbon atom, 
methane is quite exceptional and differs from all other hydro- 
carbons. 

Occurrence of Paraffins in Nature. — Methane or marsh gas 
occurs as a product of the slow decay of vegetable matter in 
presence of much water, as, for example, in stagnant pools, 
marshy places, etc., and also as the " fire-damp " of coal mines. 
Further, methane and several of its homologues are present in the 
gases which issue from the earth in the petroleum region of Penn- 
sylvania and in other parts of the world; while the crude petro- 
leum itself which flows, or is pumped, from the earth in these 
places, also consists of or contains higher members of the series. 

Formation of Paraffins in the dry distillation of coal, wood, 
shale, etc, — The volatile products obtained by the dry distillation 



382 ORGANIC CHEMISTRY. 

of these substances always contain considerable quantities of par- 
affins. Thus methane is a constant constituent, in large propor- 
tion of coal gas- and of wood gas. Further in the dry distillation 
of shale in the Scottish ' ' paraffin oil ' ' industry, besides the 
paraffins which are contained in the gaseous products, the liquid 
distillate consists largely of liquid paraffins in which solid com- 
pounds, also belonging to the paraffin series are held in solution. 

Methods for the preparation of Paraffins. — It may now conven- 
iently be shown that the process discussed on pp. 385-387 of 
building up, from one member of the paraffin series, the next 
higher member, by the replacement of a hydrogen atom by the 
methyl group, is in certain instances capable of actual experi- 
mental realization. This synthesis can be effected by several dif- 
ferent methods, and one or two of these methods may be described 
here with some detail. 

1. One hydrogen atom of methane can, without difficulty, be 
replaced by chlorine, methyl chloride, CH3CI, being produced 
(p. 396). From methyl chloride the corresponding iodine com- 
pound (methyl iodide, CHgl) could be obtained. One way to do 
this would be to convert the mythyl chloride into methyl alcohol, 
CH3OH (p. 418), and from this to prepare methyl iodide. It is 
indeed usual to prepare methyl iodide from methyl alcohol 
(p. 398), but methyl alcohol is prepared on the large scale by 
other methods (p. 418) very much more easily and cheaply than 
would be possible if it had to be obtained from methane by way 
of methyl chloride. This method is stated here, however, in 
order to show that the end in view, viz., the proportion of 
methyl iodide starting from marsh gas, is capable of attain- 
ment. 

If methyl iodide, however prepared, is dissolved in a suitable 
solvent, such as ether, and the solution is treated with metallic 
sodium, a reaction takes place which may be diagrammatically 
represented thus : — 

H H 

H— C— ;I 2Na iL-C— H 



H H 

The products are, sodium iodide (2NaI) and ethane, 

H H 

I I 
H— C— C— H2 

I I 
H H 

and the mode of its formation here furnishes strong evidence 
concerning the constitution of ethane. 

By carrying out a series of operations analogous to those de- 



PAEAFFINS. 383 

scribed in the case of methane, only starting from ethane instead, 
it is possible to prepare a derivative from this latter hydrocarbon 
also, in which the place of one atom of hydrogen is taken by 
iodine so as to form ethyl iodide, C.^11^1. On the large scale ethyl 
iodide is, however, ahvays prepared from ethyl alcohol, CgH^OH 
(p. 398) in the same way that methyl iodide is prepared from 
methyl alcohol. If ethyl iodide is dissolved in pure ether and the 
solution is treated with metallic sodium, a reaction takes place which 
is exactly analogous to that represented above methyl iodide : — 
methyl iodide : — 

CH3CHJ1 2Na lICH^CHg, 



whereby normal butane is produced ; while if the operation is 
similarly carried out, but with the employment of a mixture of 
methyl and ethyl iodides instead of ethyl iodide alone, besides 
ethane and normal butane (which may both be supposed to be 
formed according to the actions already represented above), a 
quantity of a third paraffin, propane, CgHg, is always produced. 
The formation of this paraffin may be represented thus : — 

CHgil 2Na IjCH^CHg. 



Besides by the method already described for obtaining normal 
butane from ethyl iodide by the action of sodium, this paraffin 
can also be prepared (mixed, however, Avith ethane and normal 
hexane, Cg H^^), by a method strictly analogous to that just 
given above for the preparation of propane, only employing a 
mixture of methyl iodide and normal propyl iodide, CgHI^,^ 
instead of the mixture of methyl and ethyl iodides. 

Thus by two variations of the same method, i. e. , by acting with 
sodium [a) upon solution of a single iodide, and (6) upon mixed 
solutions of two different iodides, normal paraffins can be obtained 
either with even numbers of carlDon atoms in their molecules, or 
with odd numbers (greater than one). It must be noted, however, 
that when mixed iodides are employed, a mixture of three different 
paraffins is always obtained, as illustrated above, and even the 
approximate separation of these from one another may not be 
practicable. A reaction of this kind cannot, therefore, be employed 
as a mode for preparing a single paraffin in a state of purity. 

1 The iodides are known, both with molecular weight corresponding to 
the formula C3H7I. They are called normal and iso-propvl iodides, 

h: H "h 

I I I 

and may be represented by the formulae H — C — C — C — I and 

H H H " III 

III H H H 
H— C— C — C— H respectively, 

III ■ 

H I H 



384 



ORGANIC CHEMISTRY. 



2. Paraffins are obtained (along with other products) by the 
electrolysis of solutions of potassium salts of the homologous series 
of acids to which acetic acid belongs. These acids are all regarded 
as containing a group of atoms which is called the carboxyl group 
and is supjDosed to consist of a carbon atom with its combining 
capacity three-fourths satisfied by linkage with two oxygen atoms 
{i.e., one-half by linkage with one oxygen atom which is thereby 
fully satisfied, and one-fourth by linkage with a second oxygen 
atom which, in turn, is further linked to a hydrogen atom). The 
constitution of this group may be represented graphically thus: 

O 

II 
— C — O — H. To save space, however, it is often printed — COOH. 

In the acids of the acetic series (and in carboxyl acids generally) 
the carbon atom of this carboxyl group is supposed to be further 
one-fourth linked to another carbon atom in the molecule (with 
the single exception of formic acid, the first member of the acetic 
series, in which the carbon atom of the carboxyl group is the only 
one contained in the molecule and is supposed to be one-fourth 

O 



linked to a hydrogen atom thus : H — C — — H). 

The composition of any member of the acetic series of acids may 
be represented by the general formula CnH2„02, or better by the 
more extended formula C„H,,„+i,COOH. The consideration of 
this latter mode of writing the general formula for these acids 
shows that the acids themselves may be regarded as paraffins 
(C„H2„+o) from which one hydrogen atom has been removed (leaving 
CnH,„+i), the place of this "hydrogen atom being taken by the car- 
boxyl group. It is in this light that we shall regard these acids 
for our present purpose. 

The formation of various paraffins by the electrolysis of solutions 
of the potassium salts of acids of the acetic series may be illustrated 
by the following example : — 

When a concentrated solution of potassium acetate, CH3COOK, 
is electrolyzed, it may be represented that the salt is first separated 
into potassium and the acid radical of the acetates and that other 
changes follow. Thus there are formed : 



At the Anode 

CH3COO 

which breaks up for the most part 



At the Cathode 

K 

which interacts with water, 

yielding KOH and H. The 

k atom then unites with an- ' other changes occur to some ex 
other H atom, similarly pro- , tent). Each — CH, group then 
duced, to form a hydrogen mole- i unites with another — CHsgroup, 



into— CH2 and CO^ (although 



cule, H, 



similarly produced, to form an 
ethane molecule, C^H . 



PAEAFFINS. 



385 



3. Another method for the preparation of paraffins, which is of 
somewhat general applicability, consists in heating the salts of the 
acids of the acetic series with basic hydroxides. The basic hydrox- 
ide, at a high temperature, removes carbon and oxygen from the 
salt in the proportions in which these elements combine to form 
carbonic anhydride, a carbonate and a paraffin resulting from the 
interaction. It has been found that the best results, on the whole, 
are obtained by employing the barium salts and heating these with 
barium hydroxide. Writing the general formula for the barium 
salt (in which the bivalent atom of barium must of course be 
represented as taking the places of two hydrogen atoms, i. e., of 
one each in two molecules of the acid) the change which occurs 
may be represented diagrammatically as follows : — 



C„H„ 



.0 



O- 



O 



\c- 



:Ba— O^ 



Hi — 0— Ba— 



O— 



C„H, 



2n+l 



H 



or by an equation as follows : — 

(C„H,„+iCOO),Ba + Ba(OH), = 2BaC03 + 2C„H,„+ 

Methane. Marsh gas. Light carburetted hydrogen. Methyl 
hydride. Fire-damp. CH^.- — This gaseous hydrocarbon may be 
made from its elements by combining the carbon with sulphur to 
form carbon bisulphide and the hydrogen with sulphur to form 
hydrogen sulphide, and then passing these two compounds over 
red-hot copper. It occurs naturally in coal mines and in the mud- 
A^olcanoes of the Crimea ; it is frequently associated with the crude 
petroleum that issues from the earth, and, mixed with carbonic 
anhydride and nitrogen, is constantly rising in bubbles to the sur- 
face of stagnant pools in marshy places. It is a non-illuminating 
constituent of ordinary coal-gas. It may be prepared by heating 
with a mixture of 2 parts of dry sodium acetate, 3 of lime, and 2 
of sodium hydroxide or, better, potassium hydroxide. 

CH3.CO ONa + NaOH - CH, + Na^CO^ 

Sodium acetate Sodium hydroxide Methane Sodium carbonate 

Methane prepared in this way is never quite pure, but is mixed 
with other gases of which the principal ones are hydrogen and 
ethylene (p. 392). Pure methane is obtainable by the action of 
water on zinc methide, Zi\{QlA.^.^ : — 



25 



Zn(CH3), + 2H,0 = Zn(OH), + 2CH, 



386 ORGANIC CHEMISTRY. 

Methane is a colorless and odorless gas of sp. gr. 8.07. It only 
dissolves to a small extent in water but is rather more soluble in 
alcohol. It can be condensed to the liquid state by the applica- 
tion of a moderate pressure at a very low temperature. It burns 
in air, but, when pure, with a practically non-luminous flame : 
CH, + 20., - CO2 + 2Hp. 

Mixtures of methane and air in suitable proportions give rise to 
violent explosions when fired. This occurs occasionally in insuffi- 
ciently ventilated coal mines. About ten times its volume of air 
are required for the complete combustion of any given volume of 
methane. When methane is mixed with eighteen times its volume 
of air (or more than this) the mixture does not explode on the appli- 
cation of a light. 

Ethane, CgHg. Dimethyl. Ethyl hydride. — This is one of the 
constituents of crude petroleum. It is usually prepared in quantity 
by the electrolysis of a concentrated solution of potassium acetate 
(p. 384). The mixture of ethane and carbonic anhydride which 
is given off at the positive electrode during this process is made to 
bubble through a concentrated solution of potassium hydroxide 
which absorbs the carbonic anhydride, while the ethane passes on 
unabsorbed. 

Ethane is also obtained {a) by the action of sodium upon methyl 
iodide dissolved in ether (p. 382), 2CH3l+2Na=2XaI+C2H, ; 
(6) by the action of water upon zinc ethide, Zn(C2H.)2 +2^2^ = 
Zn(0H)2 + SCiHg ; and (c) bv the interaction of zinc methideand 
methyl iodide : Zn^CHg)^ + 2CH3I = Znl2 + 2Q^li^. 

Ethane is, like methane, a colorless and odorless gas. Its sp. 
gr. is 14.95. Water dissolves less than one-tenth of its volume of 
ethane, but alcohol dissolves somewhat more than its own volume 
of it. It can be condensed to the liquid state, at about 0° C. , by 
the application of moderate pressure. It burns in air with a very 
feebly luminous flame : 

2C2Hg + 7O2 = 4CO2 + 6H2O 

Propane, methyl ethyl, CJl^. — This gas, like methane, occurs 
dissolved in the Pennsylvania petroleum springs. 

Butanes, QHjq. — As already stated, there are two isomeric 
butanes, normal butane or diethyl, C^H-.C^H., found in petroleum, 
and isobutane or trimethyl methane, CII(CH3)3, formed by artifical 
means. 

Pentanes, C.Hj2- — ^s previously stated, three varieties are 
possible, and three only are known. Ordinary amyl alcohol and 
valeric acids are derivatives of isoamyl hydride or isopentane. 

Hexanes, CpH^^. — Five are possible, five are known. 

Heptanes, C.H^g. — Nine are possible, five are known. 

Octanes, C^Hj^. — Eighteen are possible, three are known. 

Nonane, C9H20, Decane, Cj^Hg,, and every paraffin hydrocar- 



PARAFFINS. 



387 



bon up to Cg^HgQ, as well as some others, and derivatives of much 
higher members of the paraffin series of hydrocarbons, are known. 

General Character of the Paraffins. — The lower members of the 
paraffin series are gases at ordinary temperatures; the next fol- 
lowing members, beginning with butane and isobutane, are 
liquids with very low boiling points, but with the boiling points 
rising gradually, though not quite regularly, as the number of 
carbon atoms in the molecule increases. When members with 
fifteen or more carbon atoms in their molecules are reached, these 
are colorless solids at ordinary temperatures, and boil at tempera- 
tures mostly above 200° C. The paraffin wax largely used in the 
manufacture of candles consists of a number of the higher paraffins 
in a condition of mere mixture. 

The specific gravities of the liquid and solid paraffins rise grad- 
ually with the increase of molecular weight. All the paraffins 
are considerably lighter bulk for bulk than water. They are all 
very nearly insoluble in water but they are more or less soluble in 
alcohol and ether. 

As regards their chemical characters, the paraffins are remark- 
able for the resistance which they offer to the action of the 
majority of the most active oxidizing and other agents, such as the 
strong acids and alkalies generally, sodium, etc. When oxidation 
of a paraffin takes place at all, it is frequently complete, carbonic 
anhydride and w^ater being the only products formed. The par- 
affins are, however, easily attacked by chlorine in presence of 
light ; less easily by bromine. These agents act by displacing one 
or more hydrogen atoms, and substituting chlorine or bromine for 
the hydrogen so displaced, hydrochloric or hydrobromic acid being 
formed at the same time : 






CI, = C^H^n+xCl + HCl 



Br. 



CnH,„^,Br 



HBr 



Petroleum Benzin. Paraffin Oil. Paraffin. 

Petroleum Benzin, {Benzinum, U. S. P.), known also as benzolin, 
petroleum spirit and petroleum ether is a colorless, very volatile, and 
highly inflammable liquid obtained by distillation from the thin 
greenish crude petroleum, and consisting of a mixture of the 
lower members of the methane series of hydrocarbons {pentane, 
CgH,^, hexane, O^H^^, etc.). Boiling point, 113° to 140° F. (45° 
to 60° C). Sp.gr. 0.638 to 0.660 at 77° F. (25° C). (Benzene 
or benzol is quite a different liquid.) 

Purified Petroleum Benzin, {Benzinum Purificatuni, U. S. P.) 
is prepared by treating Petroleum Benzin first with sulphuric acid 
and potassium permanganate and then Avith sodium hydroxide 
and potassium permanganate and washing the product with 
water. 



388 ORGANIC CHEMISTRY. 

Paraffin Oil, Liquid Petrolatum, [Petrolatum Liquidum, U. S. P.), 
a mixture of the higher liquid, members of the methane series 
of hydrocarbons, is a clear oily liquid obtained from petroleum 
by distilling off the lower boiling portions and purifying the 
liquid residue. Sp. gr., 0.870 to 0.940. When heated with 
twice its volume of sulphuric acid, the oil is not colored and the 
acid only tinged brown ; when heated with metallic sodium the 
metal is not tarnished ; alcohol boiled with the oil should not 
become acid. Petrolatum {Petrolatum, U. S. P.), officially termed 
Unguentum Paraffini \\\ Germany, Petroleine in France, and Par- 
affinum, Molle in the British Pharmacopoeia, and known in com- 
merce by various fanciftil names (vaseline, etc.), is a semi-solid 
mixture of paraffins, usually obtained by purifying the less vola- 
tile portions of petroleum. It is yellow or light amber-colored, 
translucent, soft, unctuous to the touch, free from acidity, alka- 
linitv, odor, or taste. Specific gravity 0.820 to 0.850 at'l40°F. 
(60° C). Melts at 113° to 118.4° F. (45° to 48° C.) volatilizes 
without giving off acrid vapors, and burns with a bright flame, 
leaving no residue. Insoluble in water, scarcely soluble in cold 
absolute alcohol, freely soluble in ether, chloroform, and benzol. 
It is not saponified by solutions of alkalies. ^%ite Petrolatum 
[Petrolatum Album, U. S. P.), is a white unctuous mass, a mixture 
of hydrocarbons, chiefly of the methane series, obtained by dis- 
tilling off the more volatile portions from petroleum and purifying 
the residue. Paraffin [Paraffinum, U. S. P.), commonly termed 
paraffin wax, is a mixture of several solid hydrocarbons of the 
methane series; usually obtained by distillation from shale, separ- 
ation of the liquid oils by refrigeration, and purification of the 
solid product. It is colorless, semi-transparent, crystalline, 
inodorous and tasteless ; slightly greasy to the touch. Sp. gr. , 
0. 890 to 0. 905. Insoluble in water, slightly soluble in absolute 
alcohol, readily soluble in ether. An alcohol solution should not 
redden litmus. It melts at 125° to 135°F. (51.6° to 57.2° C), 
and burns with a bright flame, leaving no residue. 

Paraffin resists all ordinary reagents (hence the original name 
paraffin from pjarum affinis, without affinity), but may, by con- 
tinued boiling with sulphuric acid and solution of potassium 
dichromate, be oxidized to cerotic acid, C2-H.^0^. By continued 
digestion with nitric and sulphuric acids it yields acids of the 
acetic series and jmraffinic acid, Cg^H^Og (Pouchet). 



QUESTIONS AND EXEECTSES. 



Draw graphic formulse for methane, ethane, propane, butane, and 
isobutane. — How many hydrocarbons of the formula C5H12 are theoret- 
ically possible and how many are known ? — What is meant by insomerism ? 
Give several illustrations. — Give examples of polymeric substances. — 



OLEFINES. 



389 



What is meant by the term " homologous series "? — What is the general 
formula for the hydrocarbons of the paraffin series ? — Mention some of 
the sources of paraffins. — Describe three general methods for the prepara- 
tion of paraffins. — How would you prepare methane and ethane? — What 
are the substances known as petroleum spirit, paraffin oil, soft paraffin, 
and hard paraffin ? — What is the derivation of the word paraffin ? 



THE OLEFINE SERIES OF HYDROCARBONS. 

In so far as composition is concerned, any member of the olefine 
series differs from the paraffin which contains the same number of 
carbon atoms in its molecule, by containing two atoms of hydro- 
gen fewer. The general formula for the members of the olefine 
series is accordingly GJl^^. This formula indicates that for each 
atom of carbon in the molecule of an olefine there are two atoms 
of hydrogen, and hence that the composition percent, of all the 
olefines is the same, no matter how different their molecular 
weights may be. Olefines may, therefore, be looked upon as paraf- 
fins from which two atoms of hydrogen have been removed, and 
such evidence as is available tends to show that this is a satisfac- 
tory view of their constitution. Moreover, it would seem that 
the two hydrogen atoms are not to be regarded as having been 
removed from the same carbon atom, but from two different atoms, 
and that these two carbon atoms are always immediately neigh- 
boring ones in the carbon nucleus. If this latter view is well 
founded, it offers some explanation for the fact that an olefine 
with only a single carbon atom in its molecule has never been 
obtained and does not appear to be capable of existence. The 
formula for such an olefine would be CH2 but the lowest known 
member of the olefine series, i. e. , ethylene, is represented by the 
formula CgH^. 

The paraffins have already been described as saturated com- 
pounds (p. 376). It is obvious from what has been stated in the 
foregoing that the olefines cannot be regarded as saturated com- 
pounds in the sense there indicated. Thus if we derive the 



formula for 
should have 



(a) 



ethylene, CgH^, from that for ethane, C.^H^, we 



H H 

H— C— C— H 

I I 
H H 



and (6) H— C— C— H 



representing ethane and ethylene respectively. But in the form- 
ula {b) the combining capacity of each of the carbon atoms is 
represented as only three-fourths satisfied by linkage with other 
atoms whereas in the formula {a) it is represented as fully satis- 
fied. The olefines are thus ''unsaturated" compounds. It is 



390 



ORGANIC CHEMISTRY. 






customary in writing the formulae for olefines, when these formulae 
are extended so as to represent each carbon atom separately, to 
indicate the pair of carbon atoms whose combining capacity is 
supposed to be only three-fourths satisfied, by drawing two strokes, 
or, occasionally, by placing two dots between them. Thus the 
formulae for ethylene is written 

-U--^^ /^^H H^^^ ^^H 
H>C=C<H or jj>C : C<jj 

which may be contracted into H^C^CH^ or HgC : CH2 ; and in 
the same way the formula for propylene, CgH^, may be written 
HH 

H-C-C=C<H ^^ ^^3. CH : CH^. 

I 
H 

Although certain pairs of carbon atoms are represented by these 
formulae as doubly linked, the assumption that these pairs of car- 
bon atoms are inore firmly linked to each other than in the cases 
where only single linkage is represented, seems not only to be 
unsupported but rather to be controverted by the chemical behav- 
ior of the substance. 

Isomerism in the define Series. — Just as there are possible vari- 
ations in the arrangement of the atoms present in those paraffins 
which contain four or more carbon atoms in their molecules, so in 
the olefines corresponding to these paraffins such variations are 
also possible. If the formulae for ethane, propane, normal butane, 
and isobutane are considered with regard to the olefines deriv- 
able from them, it will be seen that in the cases of ethane, of 
propane, and of isobutane, the removal of one atom of hydrogen 
each from any two immediately neighboring carbon atoms, leads 
to the formula of only one olefine from each paraffin, but that in 
the case of normal butane two different formulae may be arrived 
at, depending upon which hydrogen atoms are supposed to be 
removed, thus : 



CH3 



CH„ 



CH3 CHo 



gives 



CH„ 



jives CH ; 



CH2 gives CH ; and 

I II 

CH, CH^ 

CH, 



CH, 



CH 



H-C-CH3 gi 

i 
CH, 



ves C- 



CH3 CH3 CH3 

I I I 

CH^ CH3 CH 

■CH3 ; while | gives | . and || 

CH„ CH CH 



CH„ 



I 
CH, 



CH„ 



CH3 



OLEFINES. 



391 



There are thus three possible variations of the olefine formula 
C^Hg derivable in the manner described from the two variations 
(p. 377) of the paraffin formula C^Hj^j. In agreement with this it 
is of interest to note that three olefines (and only three) have been 
obtained all with molecular weight corresponding to the formula 
C^Hg. These three are commonly represented by the formulae 
given above. It is here unnecessary to further discuss these 
olefines, or indeed any members of the series except ethylene 
(p. 392). 

The view of the constitution of olefines in accordance with which 
they are regarded as parafiins from which tAvo atoms of hydrogen 
have been removed (p. 389) gains support from some of the methods 
of general applicability by which olefines are ordinarily prepared. 
Of these methods, one may be discussed here with some detail, 
namely, that by the action of boiling alcoholic solution of potas- 
sium hydroxide upon the mono-halogen derivatives of the paraffins 
(C^Hgn+iX, where X stands for CI, Br, or I). In this interaction 
the potassium atom of the potassium hydroxide unites with the 
halogen atom of the organic halide ^ forming potassium halide (just 
as in the interactions of potassium hydroxide with many metallic 
halides) but the hydroxyl group (OH) of the potassium hydroxide 
does not take the place of the halogen atom (as is usual when 
potassium hydroxicle interacts with metallic halides). Instead of 
this the hydroxyl group unites with a hydrogen atom of the organic 
halide (supposed to be a hydrogen atom linked to a carbon atom 
immediately adjoining the one to which the halogen atom was 
linked) to form water, and an olefine is produced, thus : 

C„H,„^iX 4 KOH = KX f H,0 + C„H,„ 

That is to say, boiling alcoholic solution of potassium hydroxide 
removes hydrogen and halogen from the organic halide in the pro- 
portions in which these unite to form hydrogen halide ; and the 
products of the action are, besides the olefine, the same substances 
as would be produced by the interaction of potassium hydroxide 
and hydrogen halide (?'. e., potassium halide and water). 

It is of interest to note here that the mono-halogen derivatives 
of methane are exceptional in respect to their behavior toward 
alcoholic solution of potassium hydroxide, since potassium halide 
and methyl alcohol are produced, by the interaction, and 7io olefine : 

CH3X + KOH = KX + CH3OH 

This exceptional behavior is of importance as evidence in favor df 
the view that two different carbon atoms are concerned in the con- 

^ Halide is a general name sometimes employed to designate a halogen 
compound when it is immaterial which halogen the compound contains. 
(Compare p. 256). 



392 ORGANIC CHEMISTRY. 

dition of non-saturation of an olefine as compared with a paraffin 
(p. 389). It is obvious that a molecule of metliyl iodide, CH3I, 
cannot lose an atom of iodine from one carbon atom and an atom 
of hydrogen from another. 

In virtue of their character as ''unsaturated" compounds the 
defines combine with two halogen atoms, or with a molecule of a 
hydrogen halide to form saturated compounds of the general 
formulae CJl2J^2 ^^^ GJI^^+^X respectively. 

Occurrence of Olefines in Nature. — Certain olefines occur, mixed 
with paraffins, in some of the natural gases and crude petroleums 
which issue from the earth in various parts of the world. 

Production of Olefines in the Dry Distillation of Coal, etc. — Ole- 
fines are always present, and are valuable in illuminating constit- 
uents, in coal gas (p. 297). The ordinary coal gas supply of 
towns contains from 3 to 12 percent, by volume of olefines — chiefly 
ethylene. 

A large number of olefines have been prepared. Ethylene, CgH^ ; 
Propylene, CgHg; Butylene, C^Hg; Amylene, C^Hj^j; Hexylene, CgH^g; 
and Heptylene, C-H^^ are examples ; and many others are well- 
known. 

Ethylene, defiant Gas, Heavy Carburetted Hydrogen, CgH^. — 
This olefine can be obtained by the action of boiling alcoholic solu- 
tion of potassium hydroxide upon ethyl iodide (p. 398) : — 

O^H.I + KOH = KI + H^ 4- C,H, 

It is usually prepared, however, from common (ethyl) alcohol, 
CgH.OH, by the action upon it, at a high temperature, of concen- 
trated sulphuric acid. 

Preparation. — Ethylene may be prepared by dropping 
alcohol into a large retort or flask containing 10 ounces of 
sulphuric acid and 3 ounces of water, previously mixed, and 
heated to 160 — 165° C. The liberation of the ethylene under 
these conditions is supposed to be preceded by the formation 
of ethyl hydrogen sulphate (sulphovinc acid), C.,H.HSO^; 
which undergoes decomposition yielding as chief products ethy- 
lene and sulphuric acid. The gas is washed by passing it 
first through cold water and then through a solution of sodium 
hydroxide to free it from ether, alcohol, and sulphurous anhy- 
dride. 

Alcohol Sulphuric Ethyl hydrogen Water 

acid sulphate 

C.H^HSO. = C,H. + H,SO. 



Y\ ^ / 



^-^ 



OLEFINES. 



393 



Ethylene is a colorless gas which possesses a peculiar, although 
not unpleasant smell. It is almost insoluble in water and is only 
slightly soluble in alcohol. It can be condensed to the liquid state 
at ordinary temperatures by the application of a pressure of about 
60 temperatures. It burns in air with a highly luminous flame, 
CgH^ + 3O2 = 2CO2 + 2H2O. Ethylene combines directly with 
chlorine, with bromine, and with iodine, forming ethylene chloride, 
CgH^Clg, ethylene bromide, CgH^Br^, and ethylene iodide, C^J.^, 
respectively. The two former are liquids (pp. 398, 394) the latter is 
a crystalline solid. Ethylene further unites with hydrogen brom- 
ide and wdth hydrogen iodide, forming ethyl bromide, CgH^Br, 
and ethyl iodide, O^J. respectively. 

If the graphic formula for ethylene be assuined to be 

H H 

I I 
H— C=C— H 



(p. 390), the formulae for ethylene chloride, 



bromide, and iodide may be written as follows : — 



H H 

I I 
H— C— C— H 

I I 
CI CI 



H H 

I I 
H— C— C— H 

I I 
Br Br 



H H 

I I 
H— C— C-H 

1 1 



Additional Chemical Characters of defines. — Besides the chemi- 
cal characters of olefines already described, two others depending 
upon their nature as unsaturated compounds may be mentioned. 

1. Olefines can be converted into paraffins by direct union with 
hydrogen. This is effected by passing a mixture of the olefine 
and hydrogen through a tube packed with platinum black. 

CnHgn + H^ = C^Hgn+g 

2. Olefines are absorbed by concentrated sulphuric acid (better 
by sulphuric acid in Avhich sulphuric anhydride is dissolved) with 
the formation of compounds like ethyl hydrogen sulphate (p. 392). 



C 



„H,„+g>SO, = ^"^^"j^>SO, 



These compounds are of interest and importance in organic 
synthesis, for on heating them with water an alcohol is produced 
and sulphuric acid is reformed : 

^"^2°^>S0, + H,0 = C„H,„^,OH + g>SO, 

Ethylene Chloride, C^H^Cl.^. — When equal A'olumes of ethylene 
and chlorine are mixed over water and exposed to daylight, they 



ii 



!l 



394 



ORGANIC CHEMISTRY. 



unite very readily, with the formation of oily drops which trickle 
down the sides of the containing vessel and collect below the 
water : 



C,H, 



CI, = C^H.Cl^ 



Ethylene chloride is^ a colorless liquid, its odor resembling that of 
chloroform. It boils at 85° C. 

Ethylene Bromide, CgH^Brg. — Is prepared by bubbling ethylene 
into bromine (by which it is rapidly absorbed) until the color of 
the bromine entirely disappears. A good deal of heat is given out 
during the combination, and the bromine must be kept cold : 

C,H, + Br, = C,H,Br, 

Ethylene bromide is a colorless liquid possessing a pleasant 
ethereal smell. It boils at 133° C. 



THE ACETYLENE SERIES OF HYDROCARBONS. 

Each member of this series of hydrocarbons differs from the 
paratRn with the same number of carbon atoms in its molecule, by 
containing four atoms of hydrogen fewer. The general formula 
for the acetylene series is therefore CJ3.^^_^. 

The first member of this series is acetylene, CjH,. Other 
members are Allylene, C^H^ ; Crotonylene, C^Hg ; etc. Acetylene 
is the only one which will be treated of here. The following dis- 
cussion of one of the modes of formation of acetylene should give 
a sufficient view" of the way in which this hydrocarbon is supposed 
to be constituted. The change which takes place when the mono- 
halogen derivatives of the paraffins (C„H2„^^X) are acted upon by 
a boiling alcoholic solution of potassium hydroxide has already 
been stated on p. 391 as resulting in the removal, from each mole- 
cule, of the halogen atom and a hydrogen atom. When a di- 
halogen derivative of a paraffin (C^H.^^X,) is subjected to the same 
action an exactly analogous change usually takes place, but in 
such a case each 'molecule often loses both halogen atoms and two 
hydrogen atoms. Thus when ethylene bromide, CgH^Br, {see 
above) is employed, acetylene is produced : 

C^H^Br, -h 2K0H = 2KBr + 2H,0 + C^H, 

The action in this case can be separated in actual experiment into 
two stages : in the first, one halogen atom and one hydrogen atom 
are removed ; in the second the remaining halogen atom and 
another hydrogen atom are removed. 



ACETYLENE. 



395 



Acetylene, C^H^. — This hydrocarbon is produced by direct union 
of the elements when electric sparks are passed between carbon 
terminals in an atmosphere of hydrogen. This method of produc- 
tion is of great interest as a mode of obtaining an organic com- 
pound from purely inorganic materials. Acetylene is also pro- 
duced in small quantity in many cases of incomplete combustion 
of substances containing carbon and hydrogen. One of the best 
known instances of this is its formation in a Bunsen burner when 
the gas is kindled at the gas inlet jet (close beside the air inlet 
holes at the base of the upright metal tube). Formerly when 
acetylene was required in quantity it was obtained either from this 
source by separating it from the other products of the combustion, 
or else by the action of boiling alcoholic solution of potassium 
hydroxide on ethylene bromide as already discussed in the preced- 
ing paragraph. It is now prepared as a commercial product on 
the large scale for illuminating purposes, by the action of water 
upon calcium carbide, CaCg : 



CaC, 



2H,0 



Ca(OH)^ 



CgHj 



The solid carbide is simply treated with cold water, when a brisk 
effervescence of acetylene at once takes place. 

Acetylene is a colorless gas possessing a disagreeable odor. It 
burns in air with an intensely luminous flame : 



2C,H,+ 50,= 4CO, 



2H,0 



A mixture of acetylene and oxygen in the proportions repre- 
sented by the above equation, explodes with extreme violence on 
the application of a light. 

A striking property of acetylene (and one characteristic of hydro- 
carbons in which the group — C | C — H is assumed to exist) is 
that of combining to form compounds containing copper or silver, 
and commonly called ' ' acetylides. " Thus when acetylene is 
bubbled into an ammoniacal solution of cuprous chloride a red- 
dish-brown precipitate is produced of copper acetylide, the com- 
position of which is generally supposed to be represented by the 
formula C2H2CU2O. This copper compound is usually preserved 
in a moist condition, because when dry it is liable to explosive 
decomposition by friction or by gentle heating. It may be decom- 
posed by the action of concentrated hydrochloric acid, or better 
of potassium cyanide solution, when acetylene is liberated. 

In accordance with its character as an unsaturated compound, 
acetylene combines directly with hydrogen to form ethylene, which 
in turn combines with hydrogen to form ethane (compare p. 392). 
Acetylene also combines directly with the halogens and with 
hydrogen halides, fully saturated compounds, such as C„H.,Br , 
etc., being obtained as final products. 

A highly important character of acetylene is its convertibility 



396 ORGANIC CHEMISTRY. 

into benzene. The conversion is slowly effected by exposing it for 
some time to a high temperature, SC^H^ = CgH^. This change 
is a good example of polymerisation, and further, it furnishes an 
example of the formation of an " aromatic ' ' compound from a 
''fatty" one. 



Other Series of Hydrocai^bons. — There are other series of fatty 
hydrocarbons whose members contain hydrogen in still smaller 
proportion relatively to the carbon than is the case with the mem- 
bers of the paraffin, the olefine, and the acetylene series ; but these 
cannot be treated of here. 



QUESTIONS AND EXERCISES. 



What is the general formula for the hydrocarbons of the olefine series? 
— How many olefines of the formula CiHs are known ? — How is ethylene 
prepared and what are its properties? — How may ethylene chloride aud 
bromide be prepared ?— What is the general formula for tlie hydrocarbons 
of the acetylene series? — How is acetylene prepared and what are its 
chief properties? — How may benzene be prepared from acetylene? 



Halogen Derivatives of the Paraflins. 

The members of the paraffin series of hydrocarbons have already 
been discussed as saturated compounds, and as such they do not 
unite with the halogens to form halogen-addition products, i. e., 
products containing all the atoms of the original paraffins, and 
halogen atoms besides. But compounds can be obtained which 
may be looked upon as paraffins in whose molecules the place of 
a part or of the whole of the hydrogen is taken by halogen. Such 
compounds, of which several have been mentioned already, are 
commonly called halogen derivatives of the paraffins. It is only 
necessary to mention here some of the commoner methods for the 
preparation of these derivatives, and to discuss some of the sub- 
stances themselves which are of the greatest theoretical interest or 
practical importance. 

1. The hydrogen of the paraffins (or in some cases a part of it 
at least) can be displaced and chlorine ''substituted" for it by 
treating the paraffins with chlorine in daylight. This is called 
' ' chlorination " or " chlorine-substitution. ' ' Bromine, under the 
same conditions, behaves similarly but somewhat less readily 
unless the action is assisted by heating. Iodine, on the other 
hand, scarcely acts in this way at all. In the case of methane 
the hydrogen is removed and chlorine substituted for it in stages, 



HALOGEN DERIVATIVES OF HYDROCARBONS. 397 



with the formation of four different products, as represented by 
the four following equations : 



CH, + CI, 



HCl 



CH3CI 



CH,C1 4- CI2 = HCl + CH^CL 



CH.Cl^ + Cl^ = HCl + CHCI3 
CHCI3 + Q\ = HCl + CC], 



The products (other than the hydrochloric acid) of these four 
reactions are named as under : 



CH3CI 
CH,Cl 
CHCL 



CCl, 



Mono-chloro-methane; or methyl chloride. 
Di-chloro-methane; or methylene chloride. 
Tri-chloro-methane; or methenyl or formyl chloride; or 

chloroform. 
Tetra-chloro or perchloro-methane or carbon tetra- 
chloride. 



Starting from methane, however, more than one of the above 
four reactions take place to some extent side by side no matter how 
small the proportion is in which the chlorine is employed ; so that 
this is not a suitable method for obtaining pure intermediate 
products. 

2. Halogen derivatives of the paraffins are produced when 
hydrocarbons of the ethylene and acetylene series combine with 
halogens or with hydrogen halides to form saturated compounds. 
Thus ethylene and acetylene combine with bromine and with 
hydrobromic acid to form saturated compounds. 

3. Mono-halogen derivatives of the paraffins are prepared by 
the action of the hydrogen halides, or better, of the phosphorus 
halides upon alcohols of the general formula C^Hgn+iOH ; water, 
or an oxygenated compound of phosphorus (phosphorous or phos- 
phoric acid, or a phosphorus oxyhalide) being formed at the same 
time: 



aHon+iOH + HX = H,0 
8C„H,„^.,0H 



CnH2n + iX 



PX3= H3PO3 + 3C„H,„+,X 



When the hydrogen halides are employed the reactions never 
become complete, but a balance is eventually established owing to 
the tendency of the water formed to interact with the halogen 
derivative, and produce alcohol and acid again. When the phos- 
phorus halides are employed other reactions besides that repre- 
sented by the above equation take place to a considerable extent. 

Methyl and ethyl iodides are usually prepared by the action 
of phosphorus tri- iodide upon methyl and ethyl alcohols 
respectively : 

3CH30H+Pl3=H3P03+ 3CH3I 
3C2H,OH + Pl3=H3P03+ SC^H,! 

It is not necessary that the phosphorus tri-iodide should be pre- 
pared beforehand and then added to the alcohol. It is sufficient 



398 ORGANIC CHEMISTRY. 

to mix the alcohol with phosphorus and then to add the iodine 
slowly. Eed phosphorus is generally employed. The course of 
the reaction may fairly be assumed to consist in the formation, in 
the first place, of phosphorus tri-iodide, which then interacts with 
the alcohol as represented above. The methyl or ethyl iodide is 
distilled away from the phosphorous acid and other products of 
the reaction, and is further purified by drying over calcium chlo- 
ride and subsequent redistillation. 

Methyl Chloride, CH3CI, and Methyl Bromide, CHjBr, are 
gases at ordinary temperatures, but both can easily be condensed 
to the liquid state. The former is prepared from one of the by- 
products of the beet-sugar manufacture, and has found several 
industrial applications. 

Ethyl Chloride, Mthylis Chloridum, U. S. P., C^H.Cl, and Ethyl 
Bromide, CgH.Br, are liquids with low boiling points, and both 
have been employed as anaesthetics in dentistry. Ethyl chloride 
is produced by the interaction of dry hydrochloric acid gas with 
absolute alcohol : 

C^H.OH + HCl-C^H.Cl + H2O. 

Ethyl bromide may be prepared by gradually adding 6 parts of 
bromine to a mixture of 6 j^arts of ethyl alcohol and 1 of amor- 
phous phosphorus contained in a flask fitted with an upright con- 
denser, care being taken to keep the apparatus cool: 

SC^H^OH + PBr3 = SC^H.Br + H3PO3 

When all the bromine has been added, the mixture is poured 
into a retort and distilled over a water-bath, the resulting ethyl 
bromide freed from excess of bromine by washing with a small 
quantity of dilute sodium or potassium hydroxide, then washed 
with water, dried over calcium chloride, and redistilled. 

For the preparation of ethvl bromide on a large scale, De Yrij's 
method is preferable, C,H.HS0,^KBr=C2H-Br+KHS0, {see 
Pharm. Journ., 15th Feb., 1879), or the same method as modified 
by Greene (P. J"., 12th Julv, 1879), Eemington {P. J., 29th Mav, 
1880), or by Wolfl" (P. J. 3rd July, 1880). 

Methyl and Ethyl Iodides, CH3I and C2H J, are generally pre- 
pared by the method already described, (method 3 ante). They 
are both colorless liquids of peculiar but not unpleasant smell. 
Methyl iodide boils at 45° C. ; ethyl iodide at 72.3° C. Both 
iodides are very largely employed, and are of great importance, 
in the synthetic formation of other organic compounds. Instances 
of their employment have already been given on pp. 382, 383, 
etc. They should be kept in the dark, as exposure to light pro- 
motes decomposition with separation of iodine. 



CHLOROFORM. 



399 



Chloroform. 

Chloroform ox Tx\Q]i\oroYiiQih.2ine {Ghlor of ormum,\5 . S. P.), CHCI3. 
This very important substance is prepared in large quantity for 
use in an anaesthetic, as a solvent, and for other purposes. It is 
prepared on the commercial scale, in metal stills, by the action of 
bleaching-powder, at a temperature of about 45° C, on ordinary 
alcohol which has been diluted with about 16 to 20 times its 
weight in water. When the reaction has set in no further heat- 
ing is necessary, as sufficient heat is given out during its pro- 
gress. A mixture of substances distils off, and, on being condensed 
to the liquid state the distillate separates into two layers. The 
lower layer, which consists of crude chloroform, is separated from 
the upper aqueous layer, and is purified by shaking it with water 
and then with pure sulphuric acid (containing no trace of nitric 
acid), which chars and removes hydrocarbons, etc., but does not 
affect chloroform. It is freed from any trace of acid by agitation 
with lime, and from moisture by solid calcium chloride. It is 
finally rectified. Instead of alcohol, commercial acetone is now 
largely employed as a substitute in the preparation of chloroform, 
the product being known in trade as ^^ ketone chloroform.''^ The 
exact nature of the changes which take place in the preparation 
of chloroform from alcohol or acetone is not only complicated but 
also somewhat obscure. 

Experiment. — Place Ij fluid ounce of alcohol (90 percent.) 
and 24 ounces of water in a retort or flask of at least a quart 
capacity ; add 8 ounces of chlorinated lime and 4 of slaked 
lime; connect the vessel with a condenser, and heat the mix- 
ture until distillation commences, the source of heat then being 
withdrawn. The condensed liquid should fall into a small 
flask containing water, at the bottom of which about a drachm 
of chloroform will slowly collect. 

Chloroform is produced when chloral is warmed with aqueous 
solution of potassium or of sodium hydroxide, and for the sake of 
greater purity it is sometimes prepared from chloral in this way. 
It is stated that chloroform is also manufactured by the action of 
chlorine upon methyl chloride (compare p. 396). 

Properties. — The sp. gr. of pure chloroform is at least 1.494 at 
77° F, (25° C). It is liable to slowly decompose when exposed to 
air and light; 4CHCI3 -f 30,,= 4COCl2+ 2H,0 + 2Q\. The 
resulting chlorine may be detected by adding zinc iodide and 
starch, and the carbon oxychloride (carbonyl chloride, pbosgen, 
p. 299) by means of baryta water : 0001.,+ 2Ba(0H), = BaC6,4- 
BaCl^-l 2H2O. To render chloroform stable, a minute amount 
(1 volume in 100 or less) of absolute alcohol is necessary : hence 
the specific gravity of medicinal chloroform is about 1.476. 



400 ORGANIC CHEMISTRY, 

Chloroform is not decomposed by the action of sunlight unless 
oxygen is present, when, in the first stages of the decomposition, 
chlorine is liberated, and this, acting on the alcohol contained in 
the chloroform, produces hydrogen chloride, which is then found 
instead of free chlorine. Hence the liberation of chlorine has 
been disputed by some who have overlooked the presence of alco- 
hol in the chloroform operated on. Chloroform readily and 
entirely volatilizes at ordinary temperatures, having, to the last 
drop, its pleasant characteristic odor. It has a sweetish taste, is 
limpid, colorless, miscible in all proportions with alcohol and 
ether, and slightly soluble in water. It may be so frozen at low 
temperatures that any impurities shall remain in the still fluid 
portion (Pictet). It boils between 140° and 141.8° F. (60° and 
61°C. ). It burns with a sluggish, green, smoky flame. It reduces 
Fehling's solution. It should be neutral to test-paper, indicating 
absence of acid; give no precipitate with solution of silver nitrate, 
indicating absence of ordinary chlorides; remain colorless when 
heated with potassium hydroxide, indicating absence of aldehyde; 
and when shaken with concentrated sulphuric acid should give no 
more color than is producible by the absolute alcohol that is pres- 
ent, even after the mixture has been set aside for half an hour, 
indicating absence of hydrocarbons, etc. Alcohol may be 
detected by the iodoform test, or by shaking with a little of the 
dye termed "Hofmann's violet," which gives the chloroform a 
purple tint if alcohol be present, but affords no color with pure 
chloroform. At the temperature of melting ice, chloroform unites 
with water to form a crystalline compound, CHCI3, I8II2O. 

Chloroform is an important solvent ; it dissolves sulphur, phos- 
phorus, and iodine, as well as fats, resins. India-rubber, alkaloids, 
many alkaloidal salts, and numerous other organic compounds. 

Chromic anhydride acts on chloroform, converting it into 
phosgen, COCI2. 

Aqua Chloroformi, U. S. P., the official Chloroform Water, is 
made by repeated agitation of chloroform with distilled water till 
the water is saturated, and is preserved in presence of a slight 
excess of chloroform. 



Bromoform. 

^ro??io/bn?i or Tri-bromomethane, {Bromoformum, U. S. P.), is 
easily prepared by the gradual addition of bromine to a mixture 
of ethyl alcohol and an aqueous solution of potassium hydroxide, 
and subsequent purification of the hea^y liquid which separates. 
It is a colorless liquid of sp. gr. 2.808 which boils at 298. 4°F. 
(148°C.). 



SPIRIT OF NITROUS ETHER. 401 

Iodoform. 

Iodoform or Tri-iodomethane (lodoformum, U. S. P.), 
CHI3, is analogous in constitution to chloroform, the iodine 
occupying the place of the chlorine. It is made by mixing 
together one part of alcohol, two parts of crystallized sodium 
carbonate, and ten parts of water ; the whole being heated 
to about 150° F. (65.6° C), and one part of iodine gradually 
added in small portions. When the liquid becomes colorless, 
the iodoform is allowed to settle. It is then collected on a 
paper filter, washed thoroughly with water, and dried between 
filter paper. (This reaction forms a very delicate means of 
testing for the presence of alcohol. ) 

Iodoform is now prepared on the manufacturing scale by the 
electrolysis of a solution in aqueous alcohol of potassium iodide 
and potassium carbonate, carbonic anhydride being passed into 
the solution from time to time to convert into carbonate the potas- 
sium hydroxide formed during the electrolysis. Chloroform and 
bromoform may be obtained in an analogous manner, potassium 
chloride or bromide being substituted for the potassium iodide. 
. Iodoform occurs as yellow, shining, six-sided scales. It is vola- 
tile at ordinary temperatures; almost insoluble in water, soluble in 
alcohol or ether. Warmed with an alcoholic solution of potassium 
hydroxide, potassium formate and iodide are produced, CHI3 -f- 
4K0H = HCOOK + SKI -f 2H2O ; and the resulting fluid, 
heated with a little nitric acid, yields free iodine, recognizable by 
its color or giving a blue reaction with starch. 



Esters. 

The paraffins give rise to many substitution derivatives by dis- 
placement of their hydrogen by compound acid radicals. These 
derivatives are now commonly designated by the German word 
' ' ester. ' ' ^ The following, chiefly derived from ethane and pen- 
tane, are of pharmaceutical interest : — 

Spirit of Nitrous Ether. 

Ethyl Nitrite, Nitrous Ether, G^H^^O^.—A '^ spirit, " probably 
containing nitrous ether, was one of the earliest known medicinal 

' The name esters is now used instead of "compound ether " or " ether- 
eal salt " terms which Avere formerly in general use. The use of the word 
ether in strictly systematic chemical nomenclature, is now confined to a 
different group of organic compounds {see p. 447), but in popular language, 
and in pharmacy, the word is not always confined to this group. 
26 



402 ORGANIC CHEMISTRY. 

compounds, its discovery being generally ascribed to Raymond 
Lully. 

Experiment. — To a third of a test-tubeful of alcohol add 
about a tenth of its bulk of sulphuric acid, rather more of nitric 
acid, and some copper wire or turnings, and warm the mix- 
ture ; as soon as ebullition commences, the vapor of nitrous 
ether (with other substances) is evolved, recognizable by its 
odor. A long bent tube, kept very cool to serye as a con- 
denser, may be adapted by means of a perforated cork to the 
test-tube, and thus a little of the product may be condensed 
and collected. 

Disregarding the other products formed besides ethyl nitrite and 
aldehyde, the following equation probably represents the chief 
decompositions that occur in the interaction. An important feat- 
ure in the reaction is the reduction of the nitric to the nitrous 
radical : — 

8C2H5OH + 2HNO3 + H2SO, + Cu 
Alcohol Nitric Sulphuric Copper 

acid acid 

= 2C2H,N02 + C^H.O + 4H,0 + CuSO, 
Nitrous Aldehyde Water Cupric 

ether sulphate 

The official process for the preparation of spirit of nitrous ether 
{Spiritus ^theris Nitroei, U. S.P.), consists in allowing a solution 
of sodium nitrite to drojD slowly into a mixture (which is kept cool) 
of alcohol and sulphuric acid, separating the lighter layer of liquid, 
purifying it by washing with water and then with sodium carbon- 
ate solution, treating it with solid potassium carbonate to remove 
water, and pouring the product into a further quantity of alcohol. 



ma.'NO^ + H2SO, + SC^H.OH = 
Sodium Sulphuric Alcohol 


= 2C,H,N02 + Na,SO, + 2Hp 


Ethyl Sodium Water 


nitrate acid 


nitrite sulphate 



Properties. — Spirit of Nitrous Ether is a clear, mobile liquid 
having a very faint yellowish tinge, inflammable, of a peculiar 
penetrating, apple-like odor, and a characteristic taste. Sp. gr. , 
about 0. 823. It should not effervesce when potassium bicarbonate 
is added to it (showing absence of appreciable quantities of free 
nitrous, acetic or other acids). The aldehdyde in it may be detected 
by the potassium hydroxide test {see ''Aldehyde, Test for" in 
Index). The great tendency of aldehyde to become converted 
into acetic acid by the absorption of oxygen from the air renders 
Spirit of Nitrous Ether unstable, and pharmacists are obliged to 
neutralize such acid, generally by means of potassium bicarbonate, 
before adding it to medicines containing iodides, etc. The nitrous 



NITRO-COMPO UNDS. 403 

radical may be detected by adding a concentrated solution of ferrous 
sulphate mixed with sulphuric acid to some of the spirit of nitrous 
ether, the usual dark compound being produced. 

Spirit of nitrous ether assayed by the official process should yield 
results indicating not less than 4 percent, of ethyl nitrite. 

The reaction which takes place in the official assay is as 
follows : — 
SC^H.NO^ + 2KI + 2H2SO, = SC^H.OH + 2KHSO4+ 1^+2^0 

A very old variety of spirit of nitrous ether, or rather of ''sweet 
spirit of nitre" {Spiriius Nitri Dulcis, P. L., 1746), still sold in 
Great Britain, is made from rectified spirit and nitric acid as 
ordered in the London Pharmacopoeias, except that the distillation 
is continued until the product has a sp. gr. of 0. 850. It may 
contain little or no ethyl nitrite, but is popular as a stimulant. 

Nitro- Compounds. — There are two derivatives of ethane which 
possess the composition represented by the formula, CgHgNOj but 
which differ very much in properties, namely, ethyl iiitrite, which 
boils at 63.5° F. (17.5° C.) and has a sp. gr. of 0.900 (at 0° C. ; 
water=l ; 0.917 to 0.920 ; Dunstan and Dymond) and nitro-ethane 
which boils at 235° F. (nearly 113° C). The official spirit of 
nitrous ether contains ethyl nitrite. There are also two analogous 
derivatives of methane (CH3NO2), namely, methyl nitrite and nitro- 
methane. The nitrites are easily decomposed, and nitro-compounds 
are stable. Moreover, the reactions of the two sets of compounds 
warrant the conclusion that in the nitrites the methyl or ethyl group 
is united to oxygen, in the nitro-compounds to the nitrogen. The 
nitrites are, the nitro-compounds are not, saponifiable; on reduc- 
tion, the nitrogen of the former does not, while that of the latter 
does, remain with the radicals, yielding amines. Possibly the 
nitrites contain the nitrogen in the trivalent condition, while in 
the nitro-compounds it is quinquivalent, as represented by the 
following formulae for the compounds just mentioned as well as for 
the two corresponding derivatives of pentane, namely, amyl nitrite 
and nitro-pentane : — 

Methyl nitrite, CH3— O— N-=0. Nitro-methane, CH3— n/^ 

Ethyl nitrite, C^H.— O— N=0. Nitro-ethane, C^H,— n/^ 
Amyl nitrite, C^H,,— 0-N-O. Nitro-pentane, C^H^-N^^ 

Ethyl Acetate or Acetic Ether. 

Ethyl Acetate or Acetic Ether (JEther Aceticus, U. S. P.), 
CH3.C0.0C,H^, or C,H,C,H30,.— To a little dried sodium 
acetate in a test-tube, add a small quantity of alcohol aud some 



404 



ORGANIC CHEMISTRY, 



sulphuric acid. Adapting a long bent tube in the usual 
manner, heat the test-tube and so distil over acetic ether — 
which may be collected in another test-tube kept cool by 
partial immersion in cold water. 

On a larger scale the following proj^ortions may be used : alco- 
hol (90 2)ercent. ) 32^ fluid parts ; sulphuric acid, 32| fluid parts ; 
sodium acetate, 40 parts ; potassium carbonate, freshly dried, 6 
parts. Slowly add the acid to the alcohol, keeping the liquid cool, 
and the product being cold, add the acetate, mixing thoroughly. 
Distil forty-five fluid parts. Digest the distillate with the potas- 
sium carbonate for three days in a stoppered bottle. Separate the 
ethereal fluid, and again distil until all but about four fluid parts 
haA^e passed over. Preserve the resulting acetic ether in a well- 
closed bottle and in a cool place. It is a colorless liquid with an 
agreeable ethereal odor. Sp. gr., 0.883 to 0.885. Boiling-point, 
about 161.6° F. (72° C). Soluble in all proportions in alcohol 
and in ether. One part, by weight, dissolves in about 7 parts of 
water at 77° F. (25° C). 



C2H5OH 

Alcohol 



= CH3CO.OC2H, 

Ethvl 



acetate 



CH3.CO.ONa + H,SO, 

Sodium Hydrogen 

acetate sulphate 

NaHSO, + H,0 

Sodium hydro- Water 
gen sulphate 



Ethyl aceto-acetate, or aceto-acetic ether, is of great importance 
in synthetic chemistry, as through its means a variety of substances 
can be built up. In constitution it is the ethyl salt of aceto-acetic 
acid, and its formula is CHg.CO.CHg.COOCgH.. It is prepared 
by acting on ethyl acetate with sodium, treating the product with 
a dilute acid, and subjecting the crude aceto-acetic ether to frac- 
tional distillation. 



Amyl Acetate, CK.CO.OC.H„, or C.K^C.H.O.,.— To a 

small quantity of amyl alcohol (fusel oil may be used) in a 
test-tube add some potassium acetate and a few drops of sul- 
phuric acid, and warm the mixture ; the vapor of amyl acetate 
is evolved, recognizable by its odor, which resembles that of 
the jargonelle pear. If a condensing tube be attached, the 
acetate may be distilled over, washed by agitation with water, 
to free it from alcohol, and separated by means of a pipette. 



CH3.CO.OK 

Potassium, 
acetate 



+ C^H^.OH + H,SO, 

Amyl Sulphuric 

alcohol acid 

= CH3.C0.0C,H^, + KHSO, + H,0 

Amyl Acid potassium W^ater 

acetate sulphate 



AMYL NITRITE. 405 

Artificial Fruit-essences. — Amyl acetate, prepared with the proper 
proportions of materials, as indicated by the above equation, is 
largely manufactured for use as a flavoring agent by confectioners. 
Amyl valerate, Q^^^Q^fi^, is similarly used under the name of 
apple-oil. Ethyl butyrate, CgHgC^H^Og, closely resembles the odor 
and flavor of pine-apple ; ethyl oenanthylate, C^f^^H^fi^, recalls 
green-gage; ethyl pelargonate, C2H5CgH^^02, quince ; ethyl suber- 
ate, {Q^^f!,^^f>^, mulberry; ethyl sebacate, {Q'^^f^^^^fi^, 
melon. By mixing such esters with each other and with essen- 
tial oils in various proportions, the odor and flavor of nearly every 
fruit may be imitated. 

Amyl Nitrite. 

Amyl Nitrite, QJl^^O^ {Amylis Nitris, U. S. P.). — This may 
be prepared by the direct action of nitric acid on amyl alcohol, 
the nitric acid being reduced to nitrous by a portion of the alcohol, 
valeric aldehyde and valeric acid also being produced. The tem- 
perature must be very carefully regulated, or the reaction may 
become extremely violent; indeed, even with small quantities a 
violent explosion may occur. For experimental purposes it is 
preferable to pass the nitrous gases generated by the action of 
nitric acid on white arsenic or on starch, into the amyl alcohol 
(kept cool by placing the vessel in cold water) until the alcohol is 
saturated. The product is shaken with an aqueous solution of 
potassium hydroxide or carbonate to remove free acids, and the 
oily liquid is then separated and distilled. The portion distilling 
between 205° and 210° F. (96° to 99° C.) is amyl nitrite. 

The official amyl nitrite is a yellowish ethereal liquid ; sp. gr., 
0.865 to 0.875 ; boiling-point, 204.8° to 210.2° F. (96° to 99° C.) ; 
soluble in alcohol, insoluble in water; converted by fused potas- 
sium hydroxide into potassium valerate; exposed to the air, it 
yields amyl alcohol. It should contain 80 percent, of amyl (chiefly 
iso-amyl) nitrite. 

Amyl nitrite may contain both alpha-amyl and beta-amyl 
nitrites, iso-butyl nitrite, and propyl nitrite. These nitrites are, 
of course, derived from the corresponding alcohols ( see p. 425) 
present in the crude amyl alcohol of commerce. 

Nitropentane, QJi^^O^, is similar to amyl nitrite in composi- 
tion, but differs much in properties. It is obtained by the inter- 
action of amyl iodide and silver nitrite. It boils at 300° to 320° F. 
(148.8° to 160° C). 



QUESTIONS AND EXERCISES. 

Give details of the production of chloroform from alcohol. — Give two 
ways of preparing iodoform. — Give the formulie and state the constitution 



406 ORGANIC CHEMISTRY. 

of tlie various chlorine derivatives of methaue. — How is chloroform puri- 
fied ? — State the characters of pure chloroform. — Explain the official pro- 
cess for the preparation of nitrous ether. — Give the properties of nitrous 
ether as compared with nitro-ethane. — By what ofiicial method is the 
strength of spirit of nitrous ether to be estimated ? — How is ethyl iodide 
made ? — Mention the systematic names of several artificial fruit-essences. 
— What is the formula of amyl nitrite, and how is it prepared ? 



THE BENZENE SERIES OF HYDROCARBONS. 

TJie Benzene or Aromatic Series, C^^^_^. — This series is of great 
general interest. Just as each consecutive member of the paraffin 
series of hydrocarbons may be regarded as derived by the displace- 
ment of a hydrogen atom of the preceding member by the methyl 
(CH3) group, or of a hydrogen atom in methane by a paraffin 
radical, so the consecutive members of the benzene series of hydro- 
carbons may for convenience of study be viewed as obtained by 
the displacement of one or more hydrogen atoms in benzene by 
paraffin radicals ; as in the following examples : — 

Benzene, C^Hg. 

Toluene or Methylbenzene, C^Hg or CgH-.CHg. 

Xylene or Dimethylbenzene, CgH^o or CgH^. (CH3)2. 

Mesitylene or Trimethylbenzene, C^H^g or CgHg (0113)3. 

Cymene or Methyl-isopropylbenzene, Cj^jH^^ or CgH^.CH^.CgH^. 

The members of the benzene series are unsaturated hydrocarbons. 
A molecule of benzene itself readily unites with two, four, or six 
atoms of chlorine, forming w^hat are termed addition compounds, 
as distinguished from the substitution compounds, in which the 
hydrogen atoms in benzene are actually substituted by chlorine, 
bromine, etc. The derivatives of benzene may more or less readily 
be re-converted into benzene, a fact supporting the close structural 
or constitutional relationship existing among them. 

A number of well-known substances possessing aromatic odors 
were among the earliest known derivatives of the benzene series 
of hydrocarbons, hence the benzene series was originally termed 
the aromatic series of organic compounds. 

Benzene or Benzole. 
Benzene, CgHg (commonly known as Benzole )\ is obtained com- 
mercially from the portion of coal tar distillate boiling below 

^Note. — The student must avoid confusing coal-tar bemene, CeHe, with 
petroleum bensin, petroleum ether, benzolin, etc., ( Petroleum Sjjirit, B. P.), 
which are mixtures of paraffin hydrocarbons of lower boiling-points. 

Petroleum Benzin (U. S. P.), C5H12, CeHu, and other hydrocarbons of the 
paraffin series (of boiling-point 113-140° F.), require six times their volume 
of alcohol for solution, whereas benzene, CfiHe, dissolves in less than its 
own volume. Specific gravity of benzene about 0,871 ; of benzin 0.638 to 
0.660. 



I 



BENZENE. 407 

100° C. This distillate is partially purified by shaking succes- 
sively with sulphuric acid, water, and sodium hydroxide, and then 
redistilling ; the product still contains large quantities of toluene 
and other impurities. If pure benzene is required, the liquid must 
be cooled by means of a freezing mixture, when the benzene crys- 
tallizes out, leaving some impurities in solution ; the crystals are 
well drained. Bromine is then added to the liquid resulting from 
the melting of the crystals, until a permanent coloration results. 
The liquid is again washed with sodium hydroxide, and distilled. 
Benzene (U. S. P. ) boils at 80. 4° C. It is a colorless, limpid, highly 
refractive liquid, of sp. gr., 0.871 at 25° C. It is a valuable 
solvent of fats and oils, and under the name of "Benzine Oollas" 
was introduced by M. Collas in 1848 for cleansing purposes. 

Benzene may be obtained from benzoic acid by heating with 
lime. It is also formed on passing acetylene through red-hot 
tubes. 

When acted on by chlorine and by bromine, in the presence of a 
little iodine, benzene yields all derivatives from monochloro- and 
monobromo-benzene (C^H^Cl and CgH^Br) to hexachloro- and hexa- 
bromo-benzene (CgClg and CgBrg). Benzene also forms iodine and 
fluorine derivatives, nitro- derivatives, etc. 

Nitrobenzene (nitrobenzole, artificial oil of bitter almonds, 
or essence of mirbane), CgH.NO.^, is obtained by slowly mix- 
ing fuming nitric acid, or a mixture of nitric and sulphuric 
acids, with benzene, the vessel being kept cool by immersion 
in water. It is a yellow liquid heavier than water, having a 
strong odor resembling that of oil of bitter almonds. When 
acted on by a powerful reducing mixture such as iron and 
acetic acid, or tin and hydrochloric acid (yielding nascent 
hydrogen), is converted into aniline 

Aniline or Phenylamine, CgH^NH^.^ — Mix 13 parts of iron 
filings, 7 or 8 of ordinary acetic acid, and 31 of nitrobenzene, 
in a large flask (with an upright condenser) placed on a 
water-bath, and, after the mixture has digested for several 
hours, pour off the supernatant liquid from the deposit of iron 
filings, and distil in a current of steam. By this method the 
nitrobenzene yields, first, aniline, distilled over as a yellow oil, 
and afterward a red oil, which is a mixture of azobenzene, 
CgH,.N=.N.CgH5, hydrazobenzene, CgH^.NH.NH.CgH,, and 

CgH,N 
azoxybenzene, | /O. 

^ Aniline may be obtained from indigo, hence its name, anil being Portu- 
guese for indigo. 



ii 



408 ORGANIC CHEMISTRY. 

Aniline, CgH.NHg (mixed with toluidine, C.H^NHg), when oxi- 
dized by arsenic acid, or chlorinated lime, produces rosaniline, 
C^jjH^gNg, whose salts and derivatives form a number of the well- 
known aniline colors. 

Constitution of Amines. — Amines are usually regarded as deriva- 
tives of ammonia, one, two, or three atoms of hydrogen being 
replaced by one, two, or three univalent organic radicals, or equiv- 
alents of radicals of higher quantivalence. The products are called 
primary, secondary, and tertiary amines. The class includes certain 
alkaloids. 

Amides result when NHg displaces OH of the COOH group in 
acids. Acetic acid is CH3. CO. OH ; hence acetamide is CH3. CO. NHg. 
Aniline boiled with glacial acetic acidyieldsj9Ae/i?//-aceto??ii(/6,orace^ 
anilide [Acetanilidum, U. S. P.) or ^^antifehrine" C^H^.NH.CgHjO. 
Acetanilide is a febrifuge and a rival of '^ antipyrin,^^ phenyl- 
dimethyl-isopyrazolone, or phenazone [Antipyrina, U. S. P.) 
Cj^H^2^P, or CgH5(CH3)2C3NH20, prepared by the interaction 
of phenylhydrazine or aniline and aceto-acetic ether and methyla- 
tion of the product. Monobroni- acetanilide, CgH^Br.NH.C2H30, 
is a sedative and febrifuge. Acetphenetidin {Acetphenetidinum, 
U. S. P.) or para-acetphenetidin, or phenacetin, CgH^.OC2H5.NH. 
CgHgO, is another febrifuge. PhenocoU is amido- acetphenetidin, 
CgH,. OC2H.. NHCOCH2NH2. Bulciri, NH2CONH. CgH,. OC2H5, 
or para-phenetol-carbamide is a substance possessing an exceedingly 
sweet taste, and has been proposed for use, like saccharin, in place 
of sugar. 

Acetanilide occurs in colorless, inodorous, glistening, lamellar 
crystals, having a slightlv pungent taste. Melting-point, when 
dry, 235. 4° F. (1 1 3° C. ). ' It is soluble in 1 8 parts of boiling imter, 
and in 2.5 parts of alcohol (and in 179 parts of water at 25° C, 
freely soluble in ether, benzol, and chloroform. If acetanilide be 
heated with solution of potassium hydroxide until the odor of aniline 
is given off, and the liquid be then warmed with a few drops of 
chloroform, the unpleasant and penetrating odor of phenol-isonitrile 
(isocyanide) is developed; and an aqueous solution mixed with solu- 
tion of bromine gives a whitish precipitate (distinctions from acet- 
phenetidin). Heated with free access of air, it burns, leaving no 
residue. With sulphuric acid or with cold nitric acid it forms a 
colorless solution. A cold saturated aqueous solution does not 
affect solution of litmus (absence of fi-ee acid) and is not affected by 
test-solution of ferric chloride (absence of acetone, antipyrine, and 
salts of aniline). 

Toluene, or methyl-benzene (commercially known as Toluol), 
CgH.CHg, forms the principal portion of the coal-tar distillate 
boiling between 100°-120° C. ; it may be made synthetically by 
acting with sodium on a mixture of monochlorobenzene and methyl 
iodide. 

CgHjCl 4- CH3I + 2Na = CgH^CHg + Nal + NaCl. 



CONSTITUTION OF THE BENZENE SERIES, 409 

It is also obtained by the dry distillation of tolu balsam. It is an 
inflammable, highly refractive liquid, boiling at 111° C. It may 
be directly oxidized to benzoic acid. 



SCgH^CHg + 30^ = 2C„H,C00H 



2Hp. 



Havmg both a phenyl (CgHJ and a methyl (CH3) group in its 
molecule, it forms two sets of isomeric derivatives : one {a) in which, 
by acting on toluene in the cold, the atoms of hydrogen are dis- 
placed in the phenyl group, and the other {b) in which, by acting 
on boiling toluene, the atoms of hydrogen in the methyl group 
are displaced. 



{Monochlorotoluene, 
Dichloi'otoluene, 
Trichlorotoluene, 



CeH.CLCHs. 
C6II3CI2.CII3. 
C6II2CI3.CH3. 



f Benzyl chloride, C6H5.CH2CI. 

b \ Benzylidene chloride, CeH^.CHClj. 
[ Benzotrichloride, C6H5.CCI3. 



Benzylidene chloride, CgHg.CHClg, when acted on by glacial 
acetic acid and zinc chloride and water, yields benzaldehyde, 
CpHgCOH (Jacobsen). By acting on benzotrichloride, C^Hg.CClg. 
with water in sealed tubes, benzoic acid results. 



C,H,CCl3 



2H2O = CgH-COOH + 3HC1. 



Cymene^ ^^^11^^, para-methyl-isopropylbenzene, 
C,H,(CH3)(C3H,) 

occurs in several volatile oils, and is readily obtained by the re- 
moval of hydrogen from the terpenes (CjoHjg) of those oils. 



Constitution of the Benzene Series. 



The fact that benzene forms three addition compounds with 
chlorine, Q,^^\, C^HgCl^, and C^HgCl^, one molecule uniting with 
not more than six atoms of chlorine, and that it affords no isomeric 
monosubstitution derivatives (but only one toluene, C^H5CH3, one 
benzoic acid, CgH.COOH, etc.), led Kekule to represent benzene 
by the following figure («), in which each carbon atom is assumed 
to be three-fourths linked to adjacent carbon atoms and one-fourth 
linked to hydrogen (the benzene ring) : — 




410 



OB GAXIC CHEMISTR Y 



Fig. a. 


Fig. b. 


Fig. I 


\ 






HCl 


H 




C 


C 


1 


/\ 


^\ 


6/ \2 

1 


HC CH 


HC CH 

1 II 
HC CH 

%/ 
C 


CI 




CI 


4 


HC CH 

CI \/'Cl 


H 






c 





HCl 

Benzene Benzene hexachloride 

In a mo'aosubstitution derivative such as chlorobenzene, CgH.Cl, 
no matter where the chlorine atom is represented, it always bears 
the same relation to the benzene nucleus; hence there can be only 
one variety of such a derivative. The experimental evidence of 
the truth of this inference is as follows. Displace H in benzene 
by a radical, X, and obtain C^H.X. In the latter displace H by 
Y and obtain CgH^XY. Xow displace X by H and obtain CgH.Y. 
Lastly displace Y by X and obtain CgH.X. The first CgH.X and 
the second CgH.X are identical in properties, yet presumably the 
X in the latter is in a difierent position from that in the former; 
whence we conclude that actual position matters nothing if relative 
position is unchanged. Such hydrocarbons are symmetrical. Such 
mono-X compounds are unsymmetrical. Further displacement of 
H by X in CgH.X results in more than one variety of C^H^XX. In 
dichlorobenzene, CgH^CL,, the atoms of chlorine may (represent- 
ing benzene, for the moment, by a hexagonal figure (6), and assum- 
ing that the carbon atoms are at the angles) be placed either at 1 
and 2, 1 and 3, or 1 and 4, the chlorine atoms being linked to 
carbon atoms which are adjacent to each other in the benzene 
nucleus i ortho-posistion) ; separated from each other by one inter- 
vening carbon atom (meta-position i ; or separated fi-om each other 
by two intervening carbon atoms (para-position). So with other 
di-derivatives. In trichlorobenzene, C^H.^Clg, the atoms of chlorine 
may be placed at 1, 2, and 3 ; 1,2, and 4 ; or 1, 3, and 5 ; 1, 2, 
and 4 being the same as 1, 3, and 4 ; 1, 2, and 3, the same as 1, 6, 
and 5, etc. ; that is to say, the chlorine atoms must all three be 
linked to adjacent carbon atoms, or two may be linked to adjacent 
carbon atoms while one is linked to a carbon atom separated from 
these by an intervening carbon atom, or all three may be linked 
to carbon atoms which are separated from one another by inter- 
vening carbon atoms. So with other tri-derivatives. Hence, 
theoretically, there can only be three isomeric dichlorobenzenes 
and three trichlorobenzenes, and this has been verified by experi- 
ment. For other illustrations, see pp. 436, 437). 



ANTHRACENE SERIES. 



411 



Benzene addition compounds. — The double linkages represented 
in the formula for benzene (fig. a), may be compared with those 
in the formulae for olefines. As in the case of the olefines they 
indicate a condition of non-saturation and the capacity for form- 
ing addition compounds. It has been stated already (p. 406) that 
benzene can unite directly with two, four, or six atoms of chlor- 
ine : the product in the last case is benzene hexachloride, CgHgClg 
(fig. c). Other addition compounds can also be obtained, such 
as hexahydrobenzene, C^Hj^^, which is formed when benzene is 
heated for some time at a temperature of 260° C. with hydri- 
odic acid. 



Other Series of Hydrocarbons. 



The Naphthalene Series, CuH 



Naphthalene, Cj^Hg {Naphthalenum, U. S. P.) is the chief 
member. It is a white crystalline substance, existing in coal tar. 
By oxidation it yields phthalic acid, CgH^(C00H)2, the anhyd- 
ride of which, 0^11^(00)20, fused with phenol, forms Phenol- 
phthalein, used as an alkalimetric indicator. With other phenols 
various colored compounds are produced ; for example, with 
resorcinol fluorescein, which, treated with bromine, gives eosin. 
These compounds are termed phthaleins. Naphthalene is 
employed for increasing the luminosity of coal gas. Of the two 
naphthyl alcohols, a and ft naphthols or monoxy naphthalenes, Cj^H^ 
(OH), ft-naphthol, a powerful antiseptic, is official (BetanaphthoL 
U. S. P.). 



The Anthracene Series, C„II, 



Anthracine,C^JtL^^ or C^H / | >CgH,, is the only noteworthy 

member of this series, its importance being due to the fact that 
artificial madder, or alizarin, is formed from it by the following 
reactions :— Anthracene is first converted into anthraquinone, 

,00. 
CuHgO^ or CgH / /CgH^, by oxidation. By acting on anthra- 
quinone with fuming sulphuric acid, it is easily converted into 
a derivative, which yields potassium alizarate when fused with 
potassium hydroxide. 



412 ORGANIC CHEMISTRY. 

Chrysophamc acid and the aloins are related to anthraquinoue ; 
chrysoplianic acid being a dihydroxy-derivative of methylanthra- 
quinone, and the aloins yielding on oxidation aloxanthin or tetra- 
hydroxy-methylanthraquinone. 

Clirysophanic Acid. 

This yellow acid, C^.H^qO, or CgHalOH)^ < ^Cg-HgCHg, 

is found in yarious species of rhubarb-root [Rheum, U. S. P.), 
and, under the name of parietinic acid, in yarious common yel- 
low lichens. Kubly and also Dragendorff consider that the 
chrysophanic acid of rhubarb is only produced when a glucoside, 
chrysophaji, is acted on by a ferment in the presence of water. The 
formation of chrysophanic acid is probably, in most if not in all 
cases, preceded by the occurrence of chrysophan, or an allied sub- 
stance. The author obtained it from araroba. 

Chrysophanic acid may be obtained in crystals of a golden- 
yellow color, hence the name (from ;y/3w6f, chrusos, gold, and 
(^aivu, phaino, I shine). Its synonyms are Rhaponticin, Rheic 
acid, Rheumin, Rhubarbaric acid, Rhubarbarin, Rumicin. By 
the reducing action of hydriodic acid it yields chrj^sarobin. 
Chrysophanic acid, actual or potential, black and red-brown 
resins [Aporetin, Phoeoretin), Emodin, Rhein, and a tannoglucoside 
are considered to be the conjoint source of the therapeutic prop- 
erties of rhubarb. Erythroretin is merely a mixture of chryso- 
phanic acid, emodin, and rhein. Chrysophanic acid and emodin 
{see below) are respectiyely di- and tri-oxymethylanthraquinone. 
Ehein (C^.H^oOg, Hesse ; C^jHgO^, Tschirsch and Heuberger) was 
regarded by Hesse as tetraoxymethylanthraquinone, but appears 
to conform rather to the second formula giyen aboye. Chryso- 
phanic acid may also be obtained from seyeral species of Ritmex or 
dock. *'Eumicin"is a preparation of yellow dock. Cascara 
Sagrada, or Sacred Bark [Rhamnus Purshiana, U. S. P.), accord- 
ing to Limousin, contains chrysophanic acid, a glucoside (?), and 
a ferment, yarious resins being also said to be present. 

Emodin C^.H^jjO., as indicated aboye, is closely related to chry- 
sophanic acid. It is obtained along wi\h chry-sophanic acid in the 
preparation of the latter from rhubarb. It also occurs in black 
alder bark, according to Liebermann and Waldstein. It is said to 
be deriyed, together with glucose, from frangulin, Cg^HjoOg, the 
glucoside of the dried bark. 

Chrysarobin. 

This compound occurs in araroba, a substance found in cayities 
in the trunk of a leguminous tree {Yonacapona araroba). Ara- 
roba is also known as Goa Powder, Bahia Powder, Brazil Powder, 
and Ringworm Powder. Chrysarobin [Chrysarobiimm, U. S. P.), 



ALOINS. 413 

/C(OH)\ 
Cj-H^Pg or CgH2(OH)2<f | ^Cfifiil,, is obtained from Ara- 

roba by extracting with hot chloroform, evaporating to dryness and 
powdering. By aerial oxidation in alkaline solution it is con- 
verted into chrysophanic acid. 

Aloins. 

Aloins— The aloes of pharmacy {Aloe, U. S. P.) is an evapor- 
ated juice, doubtless much altered by the temperature to which it 
is subjected. Purified aloes (^/oe Furijicata, U. S. P.), is obtained 
from aloes by melting on a water-bath, adding alcohol, straining, 
and evaporating. Aloes contains a yellow crystalline substance, 
Aloinum, U. S. P., perhaps slightly varying chemically, but not 
medicinally, as derived from the respective species of aloes. Aloin 
is not very soluble in cold water or alcohol, but readily soluble in 
these fluids on heating. Dissolved in alkalies it rapidly absorbs 
oxygen, but it is not readily altered in neutral or acid solutions. 

Aloin may readily be obtained from aloes by warming the latter 
with three or four times its weight of amyl alcohol; pouring off 
the solution ; allowing it to stand for a few hours to crystallize ; 
and washing the deposited aloin with ether or carbon disulphide 
to remove resinous matters. 

Barbaloin, — This substance, first obtained byT. and H. Smith, 
occurs in minute crystals in Barbados aloes. It yields substitu- 
tion compounds when acted on by bromine and chlorine. Boiled 
for some time with concentrated nitric acid, barbaloin gives, 
together with oxalic and picric acids, a yellow substance, chry- 
sammic acid, which furnishes beautiful red salts (Tilden). Anth- 
racene, Ci^H^Q, has been obtained by the reduction of barbaloin. 
Isobarbaloin, O^^^fi^ (Leger), accompanies barbaloin in Bar- 
bados, Curayao, Jeff'erabad aloes. By oxidation with nitric acid 
it yields a substance apparently identical with chrysammic acid. 
It is much more easily oxidized than barbaloin, and with cold 
concentrated nitric acid it gives the red coloration (Klunge's 
reaction) hitherto attributed to barbaloin. 

Nataloin. — This substance was discovered by Fluckiger in Natal 
aloes. It crystallizes readily in rectangular plates, either from 
alcohol or from water. No bromine or chlorine substitution deriv- 
atives have yet been formed, but an acetyl compound has been 
analyzed (Tilden). Nataloin moistened with nitric acid gives a 
red coloration which does not fade. When boiled with nitric 
acid it yields no chrysammic acid, but only oxalic and picric 
acids. 

Homonataloln, 0.,^^f)^^, occurs along with nataloin in Natal 
aloes. According to Leger it is a lower homologue of mataloin, 



414 ^ ORGANIC CHEMISTRY. 

from which it can be separated by fractional crystallization from 
methyl alcohol. 

Socnloin or Zanaloin. — Histed and Fliickiger have shown that 
Socotrine or Zanzibar aloes yields an aloin distinct from those 
just described. It forms tufted acicular prisms. Nitric acid 
scarcely alters the color of socaloin. Neither socaloin nor barba- 
loin affords any color when vapor from a glass rod moistened with 
nitric acid is allowed to come into contact with a drop of concen- 
trated sulphuric acid containing a minute fragment of the aloin, 
while nataloin gives rise to a blue coloration. 

E. von Sommaruga and Egger ( ' ' Pharmacographia " arrived 
at the conclusion that the aloins form an homologous series, and 
that they have the composition indicated in the following formulae : 
Socaloin, Cj^H^gO^; Nataloin, Cj^HjgO^; Barbaloin, C^^H^^O^. 
Tilden's subsequent experiments indicate, however, that barba- 
loin and socaloin are inosmetric in the anhydrous state, but that 
socaloin and its derivatives in the hydrous condition contain more 
water of chrystallization than barbaloin. Nataloin is less soluble 
than the other aloins. Its formula, according to Leger, is G^^^^fiw 
It does not yield either chrysammic or chloro- or bromo-deriva- 
tives. According to Groenwold the formula for the aloin from the 
aloes of Barbados and Curagao is Cj^Hj^^O^, and that from Natal 
aloes G^Jl^^O^Q. The formula officially accepted for Barbaloin is 
C^gH^gO,, SHp, but Leger (1903) gives it the formula C^.H^oOg. 



QUESTIONS AND EXERCISES. 

What is the formula of benzene? How is benzene artificially and 
commercially prepared ? — Construct an equation explanatory of the pro- 
duction of aniline. — What is the relation between toluene and benzoric 
acid? — Give the formulae of naphthalene and anthracene. — Explain by 
equations the production of alizarin or artificial madder. — Mention the 
coloring principle of rhubarb. — To what is rhubarb considered to owe 
its medicinal activity? — Give tests for distinguishing the aloins. 



The student is referred to the accompanying table for a general 
view of the relations of four series of hydrocarbons (the paraffin, 
naphthalene and anthracene series) to each other. Three mem- 
bers of the paraffin series are shown, two of the benzene series, 
and one each of the naphthalene, and anthracene series. Beneath 
each hydrocarbon are given some examples of its chief deriva- 
tives. A glance along the table shows the relation of these deriva- 
tives to each other. 



TERPENES. 415 



THE TERPENE SERIES OF HYDROCARBONS. 

The terpene series have the general formula, CnH2n_4. Tereben- 
thene or pinene C^oH^g (pure oil of turpentine), is the most common ;i 

member of the series. i 

The hydrocarbons called terpenes, C^^Hj^, are very commonly 
met with as constituents of the volatile oils. Very few of these 
oils have been produced artificially. Their fragrance is chiefly sf jrj 

due to the non-terpenoid constituents (Wallach). They differ l|l|l 

from one another in the extent to which they rotate the plane of ^' '" 

polarization of light, and also in the sense of the rotation (^. e., 
right or left). They may be divided into classes, of which several 
are interesting in pharmacy : [a) Terpenes or pinenes, boiling 
at about 156° C, and found in ordinary turpentine and other 
volatile oils ; [b) sylvestrene, found in Eussian and Swedish tur- 
pentine ; (c) phellaiidrene, Isevo-rotatory (left rotating) from Phel- 
landrium aquaticum, and dextro-rotatory (right rotating) from the 
p. amygdalinaY2iY\Qij, chiefly, of Eucalyptus oils (p. 468), boiling 
point 170° C; (d) citrenes (limonenes), boiling at about 175° C, 
and derived from the different species of citrus ; (c) dipentene, 
found in some turpentines and oils of camphor and elemi ; (/) ter- 
pinene, occurring in oils of cardamoms. Camphene, fenchene and 
terpinolene are terpenes, camphene occurring naturally in certain 
oils. The sesquiterpenes have the formula C^gH^^ and include cad- 
inene, found in oils of cubebs, savin, cade, betel, camphor, galba- 
num, patchouli, juniper, asafetida, hop, and olibanum ; caryo- 
phyllene, found in oil of cloves ; and other isomers of these. They 
boil at a much higher temperature than the terpenes, but re- 
semble them in other respects. 

Oil of Turpentine {Oleum Terebinthince, U. S. P.). Turpentine 
itself is really an oleo-resin of about the consistence of fresh 
honey. It flows naturally or by incision from the wood of most 
coniferous trees ; larch {Finns Larix) yielding Venice Turpentine, 
Abies &a/samea fiirnishing Canadian Turpentine or Canada Balsam. 
{Terebinthina Canadensis, U. S. P.), the bark of Pistachia terebin- 
thus, the variety termed Chian Turpentine (containing about 1 
part of essential oil to 7 of resin), and Pinus australis {palustris), 
P. Abies, P. pinaster and P. taeda, affording the common Ameri- 
can Turpentine, {Terebinthina, U. S. P.). Pinus maritima gives 
the French or Bordeaux Turpentine, and P. picea the old fragrant 
Strasburg Turpentine, By distillation with steam, the crude tur- 
pentine is separated into colophony, rosin or resin, which remains 
in the still, and essential oil of turpentine, often termed simply tur- 
penti7ie, spirit of turpentine, or "turps,^^ which distils over. 
Mixed with alkali to saturate resinous acids, and redistilled in a 
current of steam, oil of turpentine furnishes about 80 percent, of 
rectified oil of turpentine {Qleipm Tergbinthince Recti ficat urn, U. S. P.). 



i 



416 ORGANIC CHEMISTRY. 

Pinus Sylvestris and P. Ledebourii furnish Russian turpentine 
(whicli, according to Tilden, consists of two terpenes and cymene) 
and also (Wallach) a left-rotating limonene. This turpentine is prob- 
ably a by-product in the preparation of common wood tar {Pix 
Liquida, U. S. P. ) ; its odor is very pleasant, quite different from 
that of ordinary turpentine. The leaves of the Pinus sylvestris, or 
Scotch fir, are in Germany broken down to a woolly condition, 
producing Pine Wool or Fir Wool, or wadding used in making 
vermin-repelling blankets ; and this substance, or, still better, the 
fresh leaf, by distillation wdth water, yields Fir- Wool Oil, consist- 
ing, according to Tilden, of two terpenes, like those of Eussian tur- 
pentine and cymene. The oil distilled from the fresh leaves of Pinus 
Pumilio is official [Oleum Pini,!]. S. P.). The terpene of Bordeaux 
turpentine (terebenthene) rotates the plane of the polarization of 
light more than the terpene of American turj)entine, and in the 
opposite sense — i. e., to the left. 

Oil of tui-pentine boils at about 320° F. (160° C), and abnost 
entirely distils below 356° F. (180° C. ), little or no residue re- 
maining, whereas petroleum spirit, with which turpentine might 
be mixed, covers a much wider range of temperature during its 
distillation. Petroleum spirit also, when the small round flame 
of the end of a piece of twine is brought near to some of the spirit 
in a cup, gives a momentary flash of flame at a much lower tem- 
perature than that at which turpentine flashes. Tested in the 
especially arranged flash-point apparatus of the last Petroleum Act. 
Boverton Redwood found that the flash-point of turpentine was 
lowered 10° F. by 1 percent, of petroleum spirit. The specific 
gravity of oil of turpentine is from about 0. 860 to 0. 870. 

Under the influence of heat and sulphuric acid or other chem- 
ical agents, pure oil of turpentine, C^gH^g, yields many derivatives 
of considerable chemical interest. Among them are two optically 
inactive terpene isomers named terehene and colophene, used for 
inhalation and as disinfectants and deodorizers. When acted on 
by gaseous hydrochloric acid, the product is a white crystalline 
monohydrochloride, C^oH^gHCl. In sunlight and in presence of 
moisture it slowly undergoes oxidation and hydrolysis,' forming a 
crystalline substance, C^^H^gOg. Bromine acts violently on tur- 
pentine and terpenes, giving" rise to dibromides which yield 
cymene when heated, C,oH^,Br, = C.^H,, -f 2HBr. Crystals of 
terpin hydrate (Terpini ffydras,'V. 8.F.), C^^'H^^{OU],_,lip, also 
terpinol {C^^^^^_^T{.^0, are used therapeutically instead of terebene. 
The official terebene [Terebenum, U. S. P.), is ''a mixture of 
dipentene and other hydrocarbons." It boils at 311° to 329° F. 
(155° to 165° C). 

ALCOHOLS. 

( Alcohols are the substances produced when one or more hydro- 
gen atoms of the hydrocarbons are displaced by one or more 



ALCOHOLS. 



417 



hydroxyl (OH) groups,}l forming {a) monohydroxyl derivatives 
(monohydric or monatomic alcohols), {b) dihydroxyl derivatives 
(dihydric or diatomic alcohols), etc. ; th^ are in fact hydroxide^, 
of hydrocarbon radicals, just as potassium liycfroxide, slaked lime, 
e^", are hydroxides of metallic radicals, thus : — 



C^H.OH 


KOH 


Ethyl hydroxide 

C,HXOH), 

Ethylene hydroxide, or glvcol 

C^H.COH)., 

Glyceryl hydroxide, or glycerin 


Potassium hydroxide 

Ca(OH), 

Calcium hydroxide 

Bi(0H)3 

Bismuth hydroxide 



Monohydroxyl Derivatives of Hydrocarbons ; Monohydric or Mon- 
. atomic Alcohols. 

\ The Ethyl Series of Alcohols, C^Hg^+iOH.— The alcohols, or 
carbinols (Kolbe), are primary, secondary, or tertiary, according as 
the hydyroxyl group is linked to a primary, a secondary, or a 
tertiary carbon atom ( see p. 381). Thus : — 



I I 

H— C— OH H-C— OH 

I I 

H H 

Carbinol Typical primary 
carbinol 



CM. 



-C— OH 

I 
H 



Typical secondary 
carbinol 



aH„ 



M — C— OH 

' I 

CJl^n + l 

Typical tertiary 
carbinol 



On oxidation, primary alcohols yield first aldehydes and then 
acids, the CHgOH group of an alcohol becoming COH in the 
aldehyde, and COOH, or carboxyl, in the acid ; secondary alcohols 
yield ketones, the CHOH group becoming CO, or carbonyl (as in 
acetone CH3 — CO- — CHjj), and by further oxidation break up, 
forming acids with fewer carbon atoms than the original alcohol ; 
while the tertiary yield a ketone and an acid. The primary 
alcohols alone are of practical interest to medical and pharmaceu- 
tical students. The tertiary alcohols are said to be depressants 
instead of stimulants. For examples of primary, secondary, and 
tertiary alcohols, see pp. 424 and 425. 

General Method of Preparing Primary Alcohols. — By acting on 
the monochloro-derivative of a paraffin with potassium or silver 
acetate, an ethereal salt (or ester) is produced, which when saponi- 
fied with potassium hydroxide yields the alcohol. For instance — 

C^H.Cl + AgC,H30, = C,H.C,H,0, ^- AgCl 



Ethyl 
chloride 



Silver 
acetate 



Ethyl 
acetate 



Silver 
chloride 



Q^TLfi^Ufi^ 4- KOH = C,H,OH + KC,H,0, 

Ethyl Potassium Ethyl Potassium 

acetate hydroxide alcohol acetate 

27 



418 ORGANIC CHEMISTRY, 

If the chloro-derivatives were directly acted upon by the potas- 
sium hydroxide, hydrocarbons of the olefine or acetylene series 
would result. 

The chief primary alcohols are ordinarily obtained otherwise 
than by the above general method. 

Methyl Alcohol. 

Methyl {iiedv, methu, wine, and vlrj, ule^ wood) Alcohol, or 
Carbinol, Methyl Hydroxide, CH^OH, is a product of the destruc- 
tive distillation of wood, occurring in Pyroxijlic Spirit or Wood 
Naphtha, and is now obtained in large quantities as a by-product 
in the manufacture of beet sugar. By oxidation it yields formic 
acid {see p. 325). 

Methylated Spirit. — Alcohol of about 84 percent, strength, con- 
taining 10 percent, by volume of wood naphtha, constitutes methij- 
lated spirit, a spirit issued duty free in Great Britain, for the use 
of manufacturers, the methyl alcohol, etc. , not interfering with 
certain technical applications. 

Detection of Methyl Alcohol in Presence of Ethyl Alcohol. — 
Three or four methods have been proposed for the detection 
of methyl alcohol in alcoholic liquids, in the preparation of 
which methylated spirit should not be used. The method 
official in the U. S. P. depends upon the conversion of part 
of the methyl alcohol into formaldehyde and the recognition 
of the latter. Into a test-tube of about 40 Cc. capacity, 1 Cc. 
of the alcohol or spirit to be tested is poured, and, if undiluted, 
it is made up to 10 Cc. by adding distilled water. The pro- 
portion of alcohol present should not exceed about 10 percent, 
by volume. A copper wire spiral (made by winding 1 meter 
of No. 18 copper wire closely around a glass rod 7 Mm. thick, 
making a coil about 3 Cm. long, the end of the wire being 
formed into a handle) is heated to redness in a flame free 
from soot, and is then plunged steadily quite to the bottom of 
the liquid in the test-tube and held there for a second or two. 
This treatment is repeated five or six times, the test-tube being 
immersed in cold water to keep down the temperature of the 
liquid. The liquid is then filtered into a wide test-tube and 
very gently boiled. If the odor of acetaldehyde is percepti- 
ble, the boiling is continued until this odor ceases to be clearly 
noticeable. The liquid is cooled, and 1 drop of a solution 
containing 1 part of resorcinol in 200 parts of water is added 
to it. A portion of this mixture is then introduced cautiously 
into a test-tube containing pure sulphuric acid so as to form a 



METHYL ALCOHOL. 419 

layer upon the surface of the latter ; the whole is allowed to 
stand for three minutes and the tube is then slowly rotated. 
No rose-red ring should show at the interface, indicating the 
absence of more than 2 percent, of methyl alcohol. 

Another method of detection often used by pharmacists is 
that of J. T, Miller. For the application of the test to tinc- 
tures and similar alcoholic mixtures, some of the alcohol is first 
separated by distilling off a drachm or so from about half an 
ounce of the liquid placed in a small flask or a test-tube having 
a long bent tube attached. Into a similar apparatus put 30 
grains of powdered potassium dichromate, half an ounce of 
water, 25 minims of concentrated sulphuric acid, and 30 or 40 
minims of the distillate to be tested. Set the mixture aside for 
a quarter of an hour, and then distil nearly half a fluid ounce. 
Place this distillate in a small dish, add a very slight excess 
of sodium carbonate, boil down to about a quarter of an ounce, 
add enough acetic acid to impart a feeble but distinct acid 
reaction, pour the liquid into a test-tube, add a grain of silver 
nitrate dissolved in about 30 minims of water, and heat gently 
for a couple of minutes. If the liquid then merely darkens a 
little, but continues quite translucent, the spirit is free from 
methyl alcohol ; but if a copious precipitate of dark-brown or 
black metallic silver separates, and the tube, after being rinsed 
out and filled with water, has a distinct film of silver adhering 
to it, which appears brown by transmitted light (seen by hold- 
ing it against white paper), the spirit is methylated. The 
experiments are best performed by daylight. 

Miller's test depends for its action on the reducing powers of 
formic acid. In the above operation, the ethyl alcohol becomes 
oxidized to acetic acid (the corresponding acid of the ethyl series), 
which does not reduce silver salts, a minute quantity only of for- 
mic acid being produced, while the methvl alcohol yields formic 
acid (the corresponding acids of the methyl series) in a compara- 
tively large quantity. Aldehyde, which is also a reducing agent, 
IS simultaneously produced, but is removed in the subsequent 
ebullition with sodium carbonate. 

Ethyl Alcohol. 

-Ethyl Alcohol, or Methvl Carbinol, Ethvl Hydroxide, commonly 
called simply Alcohol, G.H.OH, or CH^CH.OH.— It is a colorless 
liquid, having a boiling-point of 172.4° F. (78° G.) and sp. gr. of 
0.797. Ethyl alcohol may be obtained by passing ethvlene into 
concentrated sulphuric acid and distilling the product, ethvl hvdro- 
gen sulphate, with water : — 



420 ORGANIC CHEMISTRY. 

On the large scale alcohol is jDroduced by fermentation of certain 
kinds of sugar. All fermented bread retains a little alcohol, some- 
times as much as 1 in 400. 

Experiment. — Dissolve two or three grains of sugar in a 
test-tubeful of water, add a little yeast (a piece of the so-called 
German or dried yeast may be used), and set the tube aside 
for several hours in a warm place at a temperature of 75° to 
85° F. (23.8° to 29.4° C). Carbonic anhydride is evolved, 
and, if the tube be inverted in a small dish containing water, 
may be collected in the upper part of the tube and subsequently 
tested : the solution contains alcohol. If the experiment be 
made on larger quantities (four ounces of sugar, one of yeast, 
and a pint of water) the fermented liquid should be distilled, 
one-half being collected, shaken with a little lime, sodium or 
potassium hydroxide to neutralize any acetic acid and decom- 
pose ethereal salts, and again distilled until one-half has passed 
over ; the product is dilute alcohol. It may still be further 
concentrated or rectified by repeated similar fractional distil- 
lations. Stills can be so constructed, especially on the large 
scale, as to condense and separately deliver the substances hav- 
ing different boiling-points. 

Fermeniation. — The change known as fermentation is commonly 
the result of some vital action. Alcoholic fermentation would 
appear always to result from the development of a living vege- 
table organism and the free multiplication of its cellular structure. 
This organism is the yeast plant, Saccharomyces cerevisioe. In the 
presence of this plant, with small quantities of phosphates and 
albuminoid matter, glucose is converted into alcohol and carbonic 
anhydride, together with small proportions of glycerin, succinic 
acid, and other substances. Cane sugar, or sucrose, does not itself 
undergo alcoholic fermentation. It can, however, by various 
methods, be converted into glucose which is fermentable. Yeast 
contains a soluble ferment, inverfase, which is capable of convert- 
ing sucrose into glucose, so that by the action of yeast cane sugar 
may be converted into carbonic anhydride and alcohol, the soluble 
ferment first converting the sucrose into glucose. It has recently 
been shown that the action of the yeast plant upon glucose is also 
due to a soluble ferment or enzyme contained in the cell and termed 
zymase. 

C.Hj.Og = 2C,HgOH + 2CO2 
Glucose Alcohol Carbonic anhydride 



ETHYL ALCOHOL. 421 

Not more than 20 percent, by weight of alcohol can be obtained 
in a fermenting liquid, since alcohol itself prevents fermentation 
when present in larger proportions than this in liquid which other- 
wise would be capable of undergoing the change. 

Other kinds of fermentation, arising from the action of special 
ferments which have not received in all cases distinctive names, 
are the following : — Viscous or Mannitic fermentation, which occurs 
when beer or saccharine juices, such as that of beet-root, become 
"ropy." Gum, mannite, and carbonic anhydride, are produced. 
For Lactic and Butyric fermentation, see pp. 332 and 453. Putre- 
factive fermentation occurs when a liquid containing albuminoid 
matter is exposed to the air. Infusoria appear in the liquid, using 
up the dissolved oxygen, and the ferments of the genus vibrio are 
developed. These are protected from oxygen which is fatal to them, 
by a thin surface layer crowded with bacteria — small rod-like 
organisms having in some cases powers of locomotion. The putre- 
faction proceeds with evolution of hydrogen sulphide, methane, 
and hydrogen, together with other gases having unpleasant odors 
and of complex chemical constitution. For Acetic fermentation, see 
''Acetig Acid." For Ammoniacal fermentation, see ''Urine." 

Fermentation of certain Soluble Ferments or Enzymes. — For the 
conversion of starch into sugar by diastase, see ' ' Starch " ; of 
amygdalin into benzoic aldehyde, hydrocyanic acid, and glucose by 
emulsin, see "Amygdalin" ; of salicin into saligenin and, glucose 
see "^ Salicin" ; of potassium myronate into allyl iso-thiocyanate, 
etc., by myrosin (see p. 427) ; of cane-sugar into grape-sugar by the 
soluble ferment in yeast, see the foregoing paragraphs. Many 
soluble ferments or enzymes occur in the germinating seeds and 
other parts of plants, and play an important part in nutrition. 

The nomenclature of ferments and fermentation is now emerging 
from early confusion. The word fermentation originally described 
the action that goes on in the preparation of alcoholic liquids or 
of dough, for it is derived from the JjSitmf erveo, I boil or seethe, 
in allusion to the evolution of gas. But discoveries of ferments 
have so multiplied as to force classification, resulting in the names 
organized ferments (yeast, for example), and unorganized ferments 
(such as diastase) ; the latter are also termed soluble ferments or 
enzymes. Moreover to the action of many so-called ferments the 
word fermentation is scarcely applicable, as, though otherwise 
strictly analogous to fermentation, no gas is given off'. Hence the 
word zymosis (from ^vjioaig, zumosis, fermentation) for the action of 
organized ferments, while the soluble or unorganized ferments are 
termed enzymes, and their action one of zymolysls. 

Alcoholic Fermentation. — On the large scale the operation of alco- 
holic fermentation is carried out by the action of yeast upon mal- 
tose, a variety of sugar produced from the starch present in the 
seeds of cereals. During germination the starch of the grain, under 
the influence of a ferment called diastase which is also present, is 



422 ORGANIC CHEMISTRY, 

converted into dextrine and maltose. The chief reaction during 
fermentation results, as already stated, in the formation of alcohol 
and carbonic anhydride, though 3 percent, of glj'cerin, 0.5 of 
succinic acid, and traces of several other substances are simulta- 
neously produced (.see " Fusel Oil," p. 425). By the fermentation 
of various fruit juices and other saccharine liquids there is produced 
the alcohol present in the different kinds of wine and beer as well 
as in brandies, liquors, and distilled spirits generally. Orange Wine 
is made by the fermentation of a saccharine solution to which 
Fresh Bitter-orange Peel has been added; Sherry Wine is the 
fermented juice of the grape; Whisky {Spirltus Frumenti, U. S. P.) 
is obtained by the distillation of the mash of fermented grain and 
should contain from 37 to 47.5 percent, by weight of alcohol; Bay 
Rum or Spirit of Myrcia is made by distilling rum with leaves of 
Myrcia acris and other plants, or by dissolving their oils in alco- 
hol ; and so on. 

Alcoholic Beverages vary much in strength. Cider or apple- 
wine, perry or pear- wine, and good beer (ale and porter or stout) 
contain 4 to 7 percent, by volume of alcohol; good light wines, 
both "red" and ''white," and natural sherry, 10 to 12 percent.; 
strong sherry and port which are commonly " fortified," that is, 
contain added spirit, 16 or 18 percent.; while "spirits" (gin, 
rum, brandy, whisky, etc.), and "liquors" (ratafia, almond- 
flavored ; maraschino, cherry- flavored ; curagoa, orange-flavored; 
chartreuse, a composite-flavored liquor, etc.), are "under-proof" 
or "over-proof," terms explained in a following paragraph. 
Vermouth is an infusion of bitter and aromatic herbs and roots in 
white wine. For excise purposes "beer" is any such liquid or 
substitute which contains more than 2 percent, of proof spirit. 
The well-known effects of these spirituous fluids on the animal 
system would appear to be due primarily to alcohol, and second- 
arily to esters. Some owe a part of their effect to non- volatile sub- 
stances, for beer from which all alcohol, etc., has been removed 
by ebullition is said to have considerable effect on the human 
economy. 

Spirit of French Wine (Spiritus Vini Gallici, U. S. P.) oy Brandy 
is a colored or flavored variety of alcohol distilled fi*om French 
wine. Its color is that of light sherry, and is derived from the 
cask in which it has been kept, but it is commonly deepened by 
the addition of burnt sugar. Its taste is due to the volatile flavor- 
ing constituents of the wine, often increased by the addition of 
artificial essences. 

Ethyl Alcohol of Various Strengths. — A liquid containing 92.3 
percent, hy loeight of pure alcohol, and 7.7 percent, by weight of 
water, constitutes the official Alcohol, U. S. P. Its sp. gr. is 
0.816 at 60° F. (15.6° C). It contains 94.9 parts by volume 
of absolute ethyl alcohol, CgH^OH, and 5.1 parts by volume 
of water. 



ABSOLUTE ALCOHOL. 



423 



The official Diluted alcohol (Alcohol Bilutimi, U. S. P. ) contains 
about 41.5 percent, by weight, of absolute ethyl alcohol and 
about 58.5 percent, by weight, of water. 

Another mixture containing 50 percent, by volume, of alcohol 
is known in the U. S. Inland Revenue Service as proof spirit. ^ 

Absolute Alcohol, C.^H^OH (Alcohol Absolutum, U. S. P.), may 
be prepared by the removal of water from less strong ethyl alcohol. 
This can be accomplished, partially, by means of dry potassium 
carbonate, and more completely by means of recently fused calcium 
chloride. In operating on, say, one pint, 2 ounces of dry potas- 
sium carbonate should be placed in a bottle that can be well 
closed, and frequently shaken during two days with the spirit. 
Meanwhile put rather more than a pound of calcium chloride into 
a covered crucible, and subject it to a red heat for half an hour ; 
then pour the fused salt on to a clean stone slab, cover it quickly 
with an inverted porcelain dish, and when it has solidified, break 
it up into small fragments, and enclose it in a dry stoppered bottle. 
Put one pound of this fused calcium chloride into a flask, pour 
over it the spirit decanted from the potassium carbonate, and 
closing the mouth of the flask with a cork, shake them together 
and allow them to stand for twenty-four hours with repeated agi- 
tation. Then attaching a dry condenser closely connected with a 
receiver from which free access of air is excluded, and applying 
the flame of a lamp to the flask, distil about two fluid ounces, 
which should be returned to the flask, after which the distillation 
is to be continued until fifteen fluid ounces have been recovered. 
The product should be colorless and free from empyreumatic odor; 
its specific gravity should be from 0.794 to 0.7969, and it should 
contain not more than 1 percent, by weight of water. It is entirely 
volatilized by heat, is not rendered turbid when mixed with water, 
does not cause anhydrous cupric sulphate to assume a blue color 
even after the two have been well shaken together. What little 
water remains may, if necessary, be removed by the cautious 
addition of metallic sodium in small quantity. If more sodium is 
used than is required for all the water present, sodium ethylate is 
produced by replacement of the hydroxyl hydrogen by sodium : — 
2Na+ 2C2H.OH=2C,H,ONa^ H,. 

The most highly purified ethyl alcohol obtainable has sp. gr. 
0.7935 at 60° F. (15.5° C), and boils at 78.3° C. 

Tests. — There are no specific tests for alcohol when mixed with 
complex matters. It is, however, easily isolated and concen- 
trated by fractional distillation, and is then recognizable by 
noting its physical and chemical characters. Thus its odor and 
taste are characteristic ; it is lighter than water, volatile, color- 

^ Proof spirit is so termed from the fact that in ohleu times a proof or 
test of its strength was afforded hy moistening witli it a small qnantity of 
gunpowder and setting light to the spirit ; if it fired the powder, it was 
said to be " over-proof "; if not, " under proof." 



424 ORGANIC CHEMISTRY. 

less, and when tolerably strong, inflammable, burning with an 
almost non-luminous flame ; it readily yields aldehyde {see p. 448) 
and acetic ether {see p. 403), each of which has a characteristic 
odor ; and in hot acid solutions, alcohol reduces potassium dichro- 
mate to a green chromic salt. 

According to Lieben, 1 part of alcohol in 2000 of water can be 
detected by adding to some of the warmed liquid a small quantity 
of iodine, a few drops of solution of sodium hydroxide, again 
warming gently, and setting aside for a time; a yellowish crystal- 
line deposit of iodoform, CHI3, is obtained. Under the micro- 
scope the latter presents the appearance of hexagonal plates or 
six- rayed and other varieties of stellate crystals. 

C^HgO + 41^ + 6NaOH = CHI3 + NaCHO^ + 5NaI + 5H,0 

Other alcohols, aldehydes, gum, turpentine, sugar, and several 
other substances give a similar reaction. 

Tests of Purity. — Oil or resin is precipitated on diluting alcohol 
containing it with distilled water, giving an opalescent appear- 
ance to the mixture. Fusel oil, aldehyde, and such impurities 
are detected by means of silver nitrate {see the official test of 
purity on p. 628). Water in absolute alcohol may be detected by 
adding to a small quantity some highly dried cupric sulphate, 
which becomes blue (CuSO^, SHgO) if water be present, but 
retains its yellowish-white appearance (CuSO^), if water be absent. 

Note. — Most ethyl derivatives are formed from alcohol, for 
example, the ethyl nitrite in spirit of nitrous ether, ethyl iodide, 
etc., which have already been described. On oxidation alcohol 
yields aldehyde and acetic acid. 

Propyl and Butyl Alcohols. 

The primary and secondary propyl alcohols, CgHgCHgOH and 
(CH3)2CHOH, and the four isomeric butyl alcohols, C^HgOH (see 
below), are of little pharmaceutical interest. 



CHj — Cri2 — CXX3 Cxi 



yCH 
\CH3 



H— C— OH H— C— OH CH3— C— OH CH3-C— OH 

I III 

H H H CH3 

Primary Primary Secondary Tertiary 

normal butyl iso-butyl butyl butyl 

alcohol alcohol alcohol alcohol 

The new hypnotic known as chloretone is a trichloro-derivative 
of tertiary butyl alcohol. Its formula is CCl3(CH3)2C.OH. 

Amyl Alcohols. 

Amyl J/co/jo/,C.H^^OH, or C^HgCHgOH, is always produced 
during the preparation, by fermentation, of ethyl or common 



OTHER MONOHYDRIC ALCOHOLS. 



425 



alcohol, C2H5OH, especially when the latter is prepared from 
sugar which has been derived from starch; hence the name, 
from amyla^n, starch. The sugar from potato-starch yields a con- 
siderable quantity; hence the alcohol is often called potato oil. 
The impure amyl alcohol obtained and separated during the 
preparation of common alcohol is also termed f ousel oil ov fusel oil 
(from ^vo), phuo, to produce), in allusion to the circumstance that 
the so-called oil is not simply educed from a substance already 
containing it (as is usually the case with oils), but is actually pro- 
duced during the operation. It was described as oil probably 
because it resembled oil in not readily mixing with water ; but it 
is soluble to some extent in water, and is an alcohol homologous 
with ethyl alcohol. It often contains variable proportions of 
propyl, butyl, and capryl alcohols. {See also Valeric Acid.) It 
should be redistilled for medicinal use and the product passing 
over at 262° to 270° F. (or about 128° to 132° C.) should alone 
be collected. 

Purified fusel oil is a colorless liquid, with a penetrating and 
oppressive odor and a burning taste. It is sparingly soluble in 
water, but soluble in all proportions in alcohol, ether, and essen- 
tial oils. Exposed to the air in contact with platinum black, it 
is slowly oxidized, yielding valeric acid, C^Hg.COOH. Eight 
isomeric varieties of amyl alcohol are known, of which three 
possess pharmaceutical interest. Two of these, viz., primary inac- 
tive iso-amyl alcohol or iso-butyl carbinol and primary active amyl 
alcohol, are present in purified fusel oil, the former constituting 
much the larger proportion of it : the third isomeric variety is 
tertiary amyl alcohol. 



CH„ 



hJ- 



-CH<CH3 
OH 






I 

H 

Primary- 
inactive 
iso-amyl alcohol 



H— C- 

i 



OH 



CH, 



CH,— C— OH 



Primary 

active 

amyl alcohol 



C,H, 

Tertiary 
amyl alcohol 
Amylene hydrate" 



The constitution of the variety of amyl alcohol termed tertiary 
amyl alcohol, or dimethyl-ethyl-carbinol, is shown in the above 
graphic formula. It is used in medicine in place of chloral hydrate, 
and is known as amylene hydrate. 



Other Monohydric Alcohols. 

Among the higher alcohols of the ethyl series are the follow 



mg 



Cetijl Alcohol or Cetyl Hydroxide, C, JI.j.OH, formerly termed 
ethal, obtained by saponifying spermaceti ' {Cetaceimi, U. S. P.), 



426 ORGANIC CHEMISTRY. 

which consists of cetyl palmitate, CjgHggC^gHg^Og, or cetine. Sper- 
maceti is the solid crystalline fat accompanying sperm-oil in the 
head of the sperm whale. 

Ceryl Alcohol, Cg^H^OH, is obtained in a similar manner from 
Chinese- wax (ceryl cerotate). 

Jlelissyl Alcohol or Myricyl Alcohol, CgoHg^OH, is obtained in a 
similar manner from melissyl palmitate, the portion of beeswax 
sparingly soluble in hot alcohol. Melissyl alcohol occurs in 
Carnauba Wax, from Copernicia cerifera. Mart. {Corypha cerlfera, 
Linn.) a wax characterized by its high melting-point, 176° to 
194° F. (80° to 90° C). Yellow Beeswax {Cera Flava, U. S. P.) 
and the same bleached by exposure to moisture, air, and sunlight, 
or White Beeswax {Cera Alba, U. S. P.) is prepared from the 
honeycomb of the hive-bee. According to Brodie it consists in 
the main of cerotic acid and melissyl palmitate, with about five 
percent, of ceroleine, the substance to which the color, odor, and 
tenacity of wax are due. Among the possible adulterants of wax 
are paraffin and ceresine. The latter is the purified native ozokerite 
of Galicia, a solid hydrocarbon largely used as a substitute for 
beeswax, especially in Russia. Both paraffin and ceresine reduce 
the melting-points of wax. The quantity of paraffin and ceresine 
present as impurity may be determined by heating the wax first 
with ordinary, and afterward with fuming, sulphuric acid, which 
scarcely affect these adulterants. Pure beeswax ^ill not yield 
more than about three percent, of its weight to cold rectified spirit, 
whereas resin, etc., would be extracted by the spirit. Solution of 
sodium hydroxide extracts nothing from pure beeswax, but dissolves 
fatty acids, fats, resin, Japan- wax, etc., present as impurities and 
the alkaline fluid then yields a precipitate of acids on the addition 
of hydrochloric acid. Soap would be dissolved from wax on boil- 
ing the sample with water, and the aqueous fluid would yield fatty 
acid on adding hydrochloric acid. Flour or any starch would be 
detected in the cooled aqueous fluid by means of iodine. Waxes 
and tallows are common on leaves, fruits, and barks. 

The Allyl Series of Alcohols, C.H^n-iOH. 

Ally I alcohol, CgHg.OH, may be obtained by heating 4 parts of 
glycerin with 1 of oxalic acid, the receiver being changed at 
195° C, and the liquid collected until the temperature rises to 
260° C. The first product is formic acid, which interacts with 
glycerin, forming monoformin : — 

C.HgfOH)^ + HCOOH = H,0 + C3H,(OH)20CHO 

Glycerin ' Formic acid Water Monoformin 

This, on fiirther heating, yields allyl alcohol : — 

C3H,(0H),0CH0 = H,0 + CO^ + C3H.OH. 

By the action of the halogen acids it produces iodine, bromine, 
and chlorine derivatives, the OH being replaced by I, Br, or CI ; 



ALLYL COMPOUNDS, 



427 



these derivatives, when digested with potassium thiocyanate, yield 
allyl thiocyanate, C3H5CNS. This compound on distillation under- 
goes isomeric change, and is converted into allyl iso-thiocyanate, 
C3H5NCS, the artificial Oil of Mustard (identical with the chief 
constituent of the natural oil, Oleutn Sinapis Volatile, U. S. P.). 
Allyl iso-thiocyanate is the substance to which mustard owes its 
power of inducing inflammatory action on the skin. 

Black Mustard {Sinapis Nigra, U. S. P.) is the powdered black 
or, rather, reddish-brown mustard-seed from Brassica nigra, and 
Wiite Mustard {Sinapis alba, U. S. P.), is the white mustard- 
seed from Sinapis alba. White mustard-seed contains sinalbin, 
C30H42N2S2O15, a glucoside which, in contact with the myrosin 
present in an aqueous extract of mustard, yields iso-thiocyanate 
of the radical acrinyl, a substance which forms part of the essential 
oil of mustard. 



Sinalbiu Water 



= C^H^ONCS 

Acrinyl 
iso-thiocyanate 



C,eH,405NHSO, + CeHiA 

Sinapin acid Glucose 

sulphate 

Crude oil of mustard often contains allyl ajanide, C3H5CN. 

Black mustard- seed contains the albuminoid ferment, myrosin 
(resembling the emulsin of almonds), and also potassium myronate, 
or sinigrin. The latter is the substance which, under the influence 
of the ferment, yields the chief part of the pungent oil of mustard. 



KC,„H,,NS,03 

Potassium 
myronate 



+ 



H,0 

Water 



= KHSO, 4 

Acid potassium 
sulphate 



■ C3H5NCS + CgH.^Og 

Allyl Glucose 

iso-thiocyanate 



The quantity of myrosin in black mustard is scarcely suflicient 
to decompose the whole of the sinigrin, while in white mustard 
the quantity is more than sufficient to decompose the sinalbin. 
Hence the mosteflective mustard is a mixture of white and black. 
The ferments act most effectively, hence the maximum amount of 
pungency is produced, in mustard paste at temperaj:ures not exceed- 
ing 100° F. (37.7° C.) 

Charta Sinapis, U. S. P. , is thick, well-sized paper which has 
been coated on one side with a mixture of purified mustard and 
solution of India-rubber and dried. 

In the old Pharmacopoeia of India the seed of Brassica juncea, 
Rai, or Indian Mustard Plant, is included in addition to those of 
B. alba and B. nigra. It is the common mustard of warm coun- 
tries. It does not differ chemically from other mustard. Allyl 
compounds are also met with in several other cruciferous and 
liliaceous plants. Oil of garlic owes its odor to allyl compounds ; 
experiments carried out by F. W. Semmler show these to be allyl- 
propyl disulphide, and diallyl disulphide. 

Decylene Alcohol, C^pHjgOH, belongs to the allyl series. Men- 
thol [Menthol, U. S. P.), obtained from oil of peppermint, is said 
by some to consist wholly of this alcohol. 



, 



428 ORGANIC CHEMISTRY. 

Sulphur Alcohols, or Thio-alcohols, CH3SH, CgH.SH, etc., analo- 
gous to hydrosulphides, KSH, etc., are known. They were 
originally termed mercapfans (ynercurius captans) from the readiness 
with which they took up mercury to form compounds such as 
(C2H5S)2Hg. The vapors of thio-alcohols and many allied sulphur 
compounds have an extremely unpleasant smell. 

Sulphonic Acids are products of the oxidation of the sulphur 
alcohols just mentioned. For example : — 

2C2H,SH + SO, = 2C2H5.SO2.OH 

Ethyl-mercaptan Oxygen Ethyl-sulphonic acid 

A number of aromatic sulphonic acids may be formed by acting 
on hydrocarbons with sulphuric acid. Examples : — 

SO^<OH + C»H, = SO,<g6H5 + H,0 

Sulphuric acid Benzene Benzene-sulphonic acid Water 

SO,<^g + C,H,CH3 = S02<^«^^^^3 + H2O 

Sulphuric acid Toluene Toluene-sulphonic acid Water 

Sulphonic acids are isomeric with acid sulphites, the character- 
istic sulphonic group or radical being SO3H, but the acid sulphites 
of the organic radicals are extremely unstable, the corresponding 
sulphonic acids very stable ; the former are easily decomposed by 
potassium or sodium hydroxide while the latter are not attacked. 

Sulphonmethane [Sulphonmethanum, U. S. P.), also called sul- 
phonal, a hypontic, is a crystalline, colorless, tasteless, odorless, 
substance. It is a product of the action of a permanganate solu- 
tion on acetone-ethyl-mercaptol (CH3)2C(C2H.S)2 — a liquid result- 
ing from the interaction of hydrochloric acid, mercaptan, and ace- 
tone. Its systematic- name is diethylsulphone-dimethylmethane. 

Sulphonethylmethane {Sulphonethylmethanum, U. S. P.) also 
called trional, is diethylsulphone-methylethylmethane, and tetro- 
nal is diethysulphone-diethylmethane. 

CH3^p^S02C2H, CH„^^^S0,C2H- 

ch3>^<so:c:h: c,h>^<so:c:h 

Sulphonal ' I'rional 

^2^5^ p /-SO C2H 

Tetronal 

Saccharin {Benzosulphinidum, U. S. P. ; synonym, Benzosulphin- 
ide), Avhich is a harmless, non-alimentary, purely sweetening agent, 
two or three hundred times as sweet as sugar, is benzoyl sulphonic 
imide. Fahlberg obtains it by converting toluene into toluene- 
sulphonic acid (above) ; this into a calcium salt, then into a sodium 
salt, and the latter into toluene-sulphonic chloride, by action of 
phosphorus trichloride and chlorine ; the liquid orthochloride 



ETHERS. 



429 



into amide by ammonium carbonate ; the amide is then oxidized 
by potassium permanganate to potassium sulphamidobenzoate and 
water ; hydrochloric acid then precipitating benzoyl-sulphonic 
imide or " saccharin " with elimination of water. "Soluble sac- 
charin" is saccharin in which hydrogen is displaced by sodium. 
The following formulae illustrate the stages of manufacture : — 



Tolueiie-sulphonic 
acid 

so <CeH.COOK 

Potassium Benzoyl-sulphonic 

sulphamidobenzoate amide or " saccharin' 



Toluene-sulphonic 
chloride 



Toluene-sulphonic 
amide 

SO ^^624^0 

»^2^N Na 
" Soluble 
saccharin" 



Orthophenolsulphonic acid, CgH^OH.SOg.OH, sozolic acid, or 
aseptol, is a non-poisonous, non-irritating antiseptic. Di-iodopara- 
phenolsulphonic acid, or sozoiodol, G^Jl^lfiH.BO^.OH, has similar 
properties and is used instead of iodoform. 



QUESTIONS AND EXERCISES. 

Give an outline of the relations between alcohols and acids. — Give a 
general method of preparing the primary alcohols of the ethyl series. — 
Name the source of methyl alcohol. — What is "methylated spirit"? — 
Describe the mode of detecting methyl alcohol in a tincture. — How can 
artificial ethyl alcohol be prepared ? — Write a few sentences on the form- 
ation, purification, and concentration of alcohol, and explain the difier- 
ence between the official varieties of alcohol, proof spirit, and absolute 
alcohol. — State the proportion of alcohol commonly present in malt 
liquors, light wines, port and sherry, and " spirits " ; and state the extent 
to which spirits may be diluted without " adulteration."— Enumerate the 
characters of alcohol. — Whence is brandy obtained, and to what are its 
color and flavor due? — Give a short account of commercial amyl alcohol. 
— How is allyl alcohol prepared ? — In what relation does ally alcohol stand 
to oil of mustard and oil of garlic ? 



ETHERS. 

Ethyl Ether, or Ordinary Ether. — Into a capacious test-tube 
put a small quantity of alcohol and about half its volume of 
sulphuric acid, mix, and gently warm ; the vapor of ether, 
recognizable by its odor, is evolved. Adapt a cork and long 
bent tube to the test-tube, and slowly distil over the ether into 
another test-tube. Half the original quantity of alcohol now 
placed in the generating-tube will again will give ether ; and 
this operation may be repeated many times. 



430 ORGANIC CHEMISTRY. 

The preparation of ordinary ether is usuallj^ performed on a 
manufacturing scale. In carrying out a laboratory experiment on 
a somewhat larger scale than that described in the preceding para- 
graph (in imitation of the manufacturing process) the addition of 
alcohol, instead of being intermittent, is continuous, a tube con- 
veying alcohol from a reservoir into the generating vessel. Mix 
ten fluid ounces of sulphuric acid with twelve fluid ounces of 
alcohol in a glass retort or flask capable of containing at 
least two pints, and, without allowing the mixture to cool, con- 
nect the retort or flask, by means of a bent glass tube, with 

Fig. 40. 




Preparation of ether. 

a Leibig's condenser, and distil with heat sufficient to main- 
tain the liquid in brisk ebullition. (If a thermometer also be 
inserted in the tubulure of the retort or through the cork of the 
flask, the temperature may be carefully regulated — between 284° 
and 290° F. ; (140° and 143.3° C). As soon as the ethereal fluid 
begins to pass over, supply fresh alcohol in a continuous stream, 
and at a rate about equal to that at which the fluid distils. For 
this purpose use a tube furnished with a stopcock to regulate the 
supply, as shown above in Fig. 40, connecting one end of the tube 
with a vessel containing the alcohol supported above the level of 
the retort or flask, and passing the other end through the cork of 
the retort or flask into the liquid. When a total of fifty fluid 
ounces of alcohol has been added, and forty-two fluid ounces of 
ether have distilled over, the process may be stopped. 

To partially purify the liquid, dissolve ten ounces of calcium 
chloride in thirteen ounces of water, add half an ounce of lime, 
and agitate the mixture in a bottle with the impure ether. Leave 
the mixture at rest for ten minutes, pour off" the light supernatant 
fluid, and distil it gently until the specific gravity rises to 0.735. 
The ether and alcohol retained by the calcium chloride, and in 



ETHERS. 



431 



the residue of each rectification, may be recovered by distillation 
and used in a subsequent operation. To imitate the process of 
partial purification just described, add to the small quantity of 
ether obtained in the previous test-tube experiment, a concentrated 
solution of calcium chloride and a little slaked lime ; the latter 
absorbs any sulphurous acid that may have been produced by 
secondary decompositions, while the former absorbs water ; on 
shaking the mixture and then setting aside for a minute or two, 
the ether will be found floating on the surface of the solution of 
calcium chloride. 

Explanation of Process. — On mixing sulphuric acid and alcohol 
in equal volumes, they interact to some extent to form ethyl hydro- 
gen sulphate (sometimes termed ethyl-sulphuric, or sulphovinic, 
acid) : — 

C2H5OH + H,SO, = C2H5HSO, + 
Alcohol Sulphuric Ethyl hydrogen 

acid sulphate 

The ethyl hydrogen sulphate interacts, on warming, 
the alcohol to form ether and sulphuric acid : — 



H,0 
Water 



with more of 



C,H,OH + 



Ethyl 
alcohol 



Ethyl hydrogen 
sulphate 



= (C,H,),0 + H,SO, 



Ether, 
or C2H5-O-C2H5 



Sulphuric 
acid 



The water of the first reaction and the ether of the second distil 
over, while the sulphuric acid liberated is again attacked by alco- 
hol and reconverted into ethyl hydrogen sulphate. The effect, 
however, of a small quantity of sulphuric acid in thus converting 
a large quantity of alcohol into ether is limited, secondary reactions 
occurring to some extent after a time. The official ether {jEther, 
U. S. P.) is a colorless, very volatile and inflammable liquid, 
having a strong and characteristic odor. Sp. gr. 0.716 to 0.717. 
It contains about 96 percent, by weight of ethyl oxide {O^^fi. 
Properties. — Pure ethyl ether is gaseous at temperatures above 
95° F. (35° C.) ; hence the condensing tubes employed in its dis- 
tillation must be kept as cool as possible. At all ordinary temper- 
atures it rapidly volatilizes, absorbing much heat from the surface 
on which it is placed. A few drops evaporated from the back of 
the hand produce a well-marked sensation of cold ; and if blown 
in the form of spray, the cooling effect is so rapid and intense as 
to produce local anaesthesia. Evaporated by aid of a current of 
air from the outside of a thin narrow test-tube containing water, 
the water may be frozen. Its vapor is very heavy, more than two 
and a half times as heavy as air, and nearly forty times as heavy 
as hydrogen, Hg = 2 ; C^H^qO = 74, or as 1 to 37. In a still atmos- 
phere the vapor will flow a considerable distance along a table or 
floor before complete diffiision occurs, and as the vapor is highly 
inflammable, it is of the greatest importance to keep candle and 
other flames at a distance during manipulations with ether. Ex- 



432 ORGANIC CHEMISTRY. 

posed to the action of air and light, ether undergoes some decom- 
position and then contains a little hydrogen peroxide. 

The official ether of the U. S. P. is a colorless mobile liquid 
having a characteristic odor and a burning sweetish taste. It is 
composed of about 96 percent., by weight, of absolute ether or 
ethyl oxide, and about 4 percent, of alcohol with a little water. 
It boils at about 96° F. (35.5° C), and its sp. gr. is 0.716 to 0.717 
at 77° F. (at 25° C). 

Mixed Ethers. — That CgH. — — CjH. represents the consti- 
tution of ether is indicated by the result of the reaction of, say, 
methyl alcohol on ethylsulphuric acid, a single definite substance, 
methyl-ethyl ether, CH^ — — C2H^, resulting. 

Ethers of various radicals, E — O — R, and several mixed ethers, 
R — — W, are known ; also sulphur ethers or thio-ethers, such as 
(CH3),S, (C,H,),S, etc. 

Spiritus JEtheris, U. S. P., Spirit of Ether, is a mixture of 
325 parts of common ether {jEther, U. S. P.), with 675 parts of 
alcohol. 

Ethylene Sulphate, CgH^SO^, is said to be contained in *'Hoif- 
mann's Anodyne, " Compound Spirit of Ether (Spiritus ^theris 
Compositus U. S. P.), a solution of ethereal oil in ether and 
alcohol. The so-called ''heavy oil of wine " is obtained by 
digesting alcohol and sulphuric acid together, then distilling and 
washing the oily distillate with distilled water. The product is a 
mixture consisting probably of ethylene sulphate, ethyl sulphate, 
ether, dissolved ethylene, and other substances. Ethereal oil, 
(Oleum JEthereum, U. S. P.) is a mixture of equal parts of heavy 
oil of wane and ether. 

AROMATIC ALCOHOLS (C„H,,_,OH Series.) 

Phenols. — These are alcohols in the sense of being hydroxy! 
derivatives of hydrocarbons. They possess in a slight degree the 
character of acids, forming compounds wdth metals w^hich to some 
extent resemble salts. Unlike the paraffin alcohols, they do not 
yield aldehydes, acids, or ketones on oxidation. 



Phenol. 

Phenol, Phenic Alcohol, Phenic Acid, or Carbolic Acid,^ 
CgHpH, may be prepared by heating benzene with sulphuric 
acid, whereby benzene-sulphonic acid, C^H.HSOg, is obtained. 
This, when heated with potassium hydroxide yields potassium-phe- 
nol or potassium carbolate, and the latter w^hen treated with acids, 
yields phenol : — 

'Orrliiiary carbolic acid is a mixture of phenol with cresol and other 
horaologucs of phenol. 



AROMATIC ALCOHOLS. 433 



qH.HSO, + 3K0H = 


CgHgOK + K2SO3 -f 2H,0 


Benzene- ' Potassium 


Potassium Potassium Water 


sulphonic acid hydroxide 


carbolate sulphite 



Commercially, phenol is obtained from that part of coal-tar 
boiling between 356° and 374° F. (180° and 190° C). When 
purified, it is a colorless^ crystalline solid, of melting point not 
lower than 104° F. (40° C), {Phenol, U. S. P.). A crystalline, 
so-called hydrous, acid, Q^^0H,1A^0, may also be obtained. 

Phenol is only slightly soluble in water, but is readily 
dissolved by alcohol, ether, and glycerin {Glyceritum Phenol, 
U. S. P.). At 60° F. (15.5° C), 100 parts of the acid are lique- 
fied by the addition of 5 to 10 parts of water (9 of acid and 1 of 
water forming Phenol Liquef actum, IT. S. P. ). At the same tem- 
perature 100 parts of phenol dissolve 30 to 40 of water, and are 
dissolved by 1800 to 1200 of water, the former of these numbers 
being said to be characteristic, of the acicular, and the latter of 
the pulverulent variety of the acid. Of the small, separate crystals 
which are official, 1 part dissolves in 12 of water. 

At temperatures above 95° F. (35° C.) phenol is an oily liquid. 
In odor, taste, and solubility (and in appearance when liquefied by 
heat or by the addition of 5 percent, of water) it resembles creo- 
sote, a wood-tar product for which it has been substituted;. 
Besides phenol, coal-tar oil contains cresol or cresylic acid 
C.H^OH, or CgH^CHgOH, while wood-tar oil furnishes guaiacol, 
C-HgOg — also a product of the destructive distillation of guaia- 
cum-resin, boiling point 392° F. (200° C.) — and creosol, CgHj^Og, 
or CgHgCHg. OH.OCH3, the mixture constituting creosote. Guaia^ 
cal {Guaiacol, U. S. P.), which ,may also be prepared syntheti- 
cally, is a colorless crystalline solid of melting point 83.3° F. 
(28. 5° C. ), or a colorless refractive liquid boiling at 401°F. (205° C.) 
Guaiacol carbonate (G'^waiaco/i-s carbonas, U. S. P.) may be prepared 
by the action of carbonyl chloride on sodium guaiacolate. Certain 
coloring-matters may be obtained by the oxidation of phenol: 
thus the addition of a small quantity of a solution of a hypo- 
chlorite to phenol which has been mixed with ammonia or, still 
better, with aniline (phenyl-ammonia or phenylamine) produces a 
blue liquid. No very satisfactory chemical method can be found 
for distinguishing creosote from phenol, as creosote contains phenol. 
Some physical differences exist : thus, phenol does not affect the 
plane of polarization of a ray of polarized light; creosote rotates it to 
the left or slightly to the right according to variations in the sub- 
stances present in it. Phenol is either solid or may be solidified 
by cooling ; creosote is not solidified at the low temperature 
attained by mixing hydrochloric acid and sodium sulphate. Creo- 
sote from coal (impure or crude phenol) yields a jelly when shaken 

: ^ Phenol soon assumes a pink color owinj; (Fabrini) to the action of liy- 
.drpgen peroxide and ammonia in presence of traces of copper, iron, or lead. 

■ 28 . 



434 ORGANIC CHEMISTRY. 

with albumin or with collodion; creosote from wood [Creosotum, 
U. S. P.) is scarcely affected, especially if quite free from traces of 
phenol. Coal-creosote is soluble in solution of potassium hydrox- 
ide and in ammonia water (Read); wood-creosote is scarcely solu- 
ble. The coal-tar product is soluble in twenty times its 
volume of water, and a neutral solution of ferric chloride pro- 
duces a more or less permanent green or blue color with the 
liquid; wood-creosote is less soluble [Aqua Creosoti, U. S. P., is 
said to contain 1 in 129) and is not permanently colored blue by 
ferric chloride. An alcoholic solution of the coal-tar creosote is 
colored brown by farric chloride, a similar solution of wood-creo- 
sote green. A dilute solution of creosote, such as creosote water, is 
not affected by agitation with spirit of nitrous ether while a similar 
solution of phenol becomes red. A few drops of spirit of nitrous 
ether are placed in a test-tube with about a drachm of the 
aqueous liquid, and an equal volume of sulphuric acid is poured 
down the sides of the tube. A pink or red color results if phenol 
be present, especially after standing for a short time(Eykman; 
MacEwan). A solution of phenol gives, with excess of bromine 
water, an insoluble white precipitate of tribromophenol, CgH^Brj 
OH. This reaction is useful in quantitative determinations of phe- 
nol. The determination of the amount of iodine absorbed by alka- 
line solutions of this and other phenols (thymol, naphthol, etc., 
serves also for quantitative purposes. According to Morson pure 
creosote is not dissolved when mixed with an equal volumeof com- 
mercial glycerin, while phenol is miscible in all proportions and, if 
present in the creosote, will carry a considerable quantity of it into 
solution. Creosote is, obviously, a mixture of substances and may 
vary somewhat in composition. 

Phenol and alkalies yield carbolates or phenafes, such as 
CpH.OK and CpH.ONa. Alcoholic solutions of the latter and of 
mercuric chloride yield yellow crystalline mercuric phenate or 
phenol-mercury, ( C^H.O ) ^Hg. 

Phenol is a powerful antiseptic (avn, anti, against and ct^ttw, sepo, 
to putrefy). In large doses it is poisonous, antidotes being a 
mixure of olive-oil and castor-oil, freely administered, or a 
mixture of slaked lime with about three times its weight of sugar 
rubbed together with a little water. Phenol is attacked by hot 
sulphuric acid, sulphocarholic or para - phenolsulphonic acid, 
CgH^(0H)S03H, being formed. On diluting the product and 
mixing with oxides, hydroxides, or carbonates, phenolsulpho- 
nates are formed. The formula of sodium phenolsulphonate is 
NaCgH,S0„2H,O,or C,H^(OH)SO,Na, 2H,0. It is obtained by 
heating a mixture of phenol and excess of sulphuric acid for some 
time to 100°-110° C, and converting the para-phenosulphonic acid 
so obtained into a sodium salt, by first treating the mixture with 
barium carbonate, which forms insoluble barium sulphate and a 
"solution of barium sulphocarbolate, filtering, and treating the 



PHENOL. 435 

filtrate with sodium carbonate. It forms colorless, neutral, pris- 
matic crystals {Sodli Phenolsulphojias, U. S. P.). Zinc Phenol- 
sulphormte, [CgH^(OH)SO.J ,Zn, SH^O {Zinci Phenolsulq^honas, 
U. S. P; ), may be obtained by saturating sulphophenolic acid 
with zinc oxide. 

Trinitro-phenol, CgH2(N02)30H, is formed on slowly dropping 
phenol into fuming nitric acid ; it is the yellow dye known as 
carbazotic acid, or picric acid. Most of the picrates are explosive 
by percussion, and picric acid itself forms, when fused, the 
explosive known as lyddite. 

Both phenol and benzene are products obtained in the manu- 
facture of coal-gas ; hence the word phenic and thence phenyl (from 
^aiva, phaind, I light, an allusion to the use of coal-gas). 

By heating phenol with zinc dust, benzene results, — 

CgH^OH + Zn = ZnO + CgH,. 

Cresol or Tolyl Alcohol, C,H,OH or C.HpH.CH.,, one of the 
hydroxytoluenes, is always found in crude phenol ; artificially it 
may be made by the same general method as phenol, by acting on 
toluene with sulphuric acid and heating the resulting sulphonic 
acid, CgH^(S03H)CH3, with potassium hydroxide. With ferric 
chloride it gives a brown coloration. The three isomeric forms, 
ortho-, meta-, and para-, are known ; Cresol, U. S.P. is a mixture 
of them. 

Benzyl Alcohol, Phenylcarbinol, C^HgCHgOH, is isomeric with 
cresol, but has the hydroxyl group in the methane nucleus, and 
not in the benzene nucleus of toluene. Having the CHgOH group, 
it yields on oxidation benzaldehyde, CgH^COH (oil of bitter 
almonds), and benzoic acid, CgH^COOH. 



Dihydroxy I- Derivatives of Hydrocarhons ; Dihydric or 
Diatomic Alcohols. 

Glycols. C,H2,(0H), series. 

Glycols may be regarded as dihydroxyl -derivatives of the paraf- 
fins, the alcohols of the ethyl series being monohydroxyl-deriva- 
tives : — 

C,Hg C,H,OH aH,(OH), 

Ethane Ethyl alcohol Glycol 

They are prepared by acting on di-iodo-derivatives of the paraffins 
with silver acetate, and then treating the product with potassium 
hydroxide. 

C,nji, + 2CH,C00Ag = (CH,C00),C2H, + 2AgI 

Di-iodo-ethane Silver Ethylene Silver 

acetate acetate iodide 



^tjJM 



436 ORGANIC CHEMISTRY. 

(CH3COO),C2H, -f 2KH0 = C.H.COH), -f 2CH3COOK 

Ethylene acetate Potassium hydroxide Glycol Potassium acetate 

The glycols yield very interesting products on oxidation, form- 
ing two sets of acids, the lactic and the succinic series. 

Aromatic Glycols, CuH2^_g(OH)2. Dihydroxyl-derivatives of 
benzene. 

Resorcinol {Resorci7iol, U. S. P.), pyrocatechin, and hydro- 
quinone : — 

When two atoms of hydrogen in benzene are displaced by two 
hydroxyl groups one of the three possible isomeric compounds is 
resorcinol, Q^^{01A\, a colorless, crystalline antiseptic having 
many advantages over phenol in surgical operations. Its name 
was given in allusion to its original source, resin, and to certain 
similarities with orcin. It occurs in white flat prisms readily 
soluble in most liquids. It may be made by passing benzene 
vapor into hot sulphuric acid and heating the product (benzene 
meta-disulphonic acid, CgH^(S0a.0H)2) with excess of sodium 
hydroxide. 

C.H.lSO^.ONa)^ + 2NaH0 = CJ1,{0YL\ + SNa.SOg 

Sodium benzene Sodium Resorcinol Sodium 

meta-disulphonate hydroxide sulphite 

Resorcinol is one of the three isomeric dihydroxyl-benzenes. 
The chemical relationships of these isomers warrant the conclusion 
that the differences in their properties are due to differences in 
the relative positions of the two hydroxyl groups in the molecules, 
as represented by the following formulae : — 

C(OH) C(OH) C(OH) 

^\ ^\ ^\ 

HC C(OH) HC CH HC CH 

I II I II I II 

HC CH HC C(OH) HC CH 

%/ %/ ~V/ 

CH CH C(OH) 

Ortho-dihydroxy- Meta-dihydroxy- Para-dihydroxy- 

benzene (pyrocatechin) benzene (resorcinol) benzene (hydroquinone) 

These formulae may conveniently be shortened as follows : — 

C TT <-0H C H ^^H C H<'^^ 

^A<OH(o) ^«^^<0H(,,) ^«^<OH(p) 

Among the benzene or aromatic compounds there are many 
similar sets of three isomeric di-substitution derivatives (three 
xylenes, three phthalic acids, etc.), the occurrence of which is 
in complete agreement with the " benzene ring " hypothesis of 
Kekule as to the constitution of benzene compounds. 



GLYCERIN. 437 

Orcin, or dihydroxy-toluene, CgH3(OH)2CH3, is found in lichens. 

Saligenol or saligenia is a hijdroxy-benzyl alcohol, salicyl alcohol, 
C H OH.CH.^OH. It is obtained from the salicin of willow bark. 
Having a hydroxyl group in the methane nucleus as well as in the 
benzene nucleus, salicylaldehyde, CgHpH.COH, and salicylic 
acid,CgH^OH.COOH, are formed on oxidation. 

Trihydroxyl-Derivatives of Hydrocarbons; Trihydric or 
Triatomic Alcohols. 

Glycerol series, C„ H2^_i(OH)3. The only member of this series 
which we shall consider here is : — 

Glycerin. 

Glycerol,^ propenyl alcohol, glycerin, C3Hg(OH)3. — The pro- 
penyl or glyceryl radical of glycerin in combination chiefly with 
the acid radicals of oleic, palmitic, and stearic acids, forms most 
of the solid fats and fixed, i.e., non- volatile oils. When these 
latter substances are heated with metallic hydroxides, interaction 
occurs, oleate, palmitate, or stearate of the metal is formed, and 
glycerin (glyceryl hydroxide) is set free. Hence glycerin is a by- 
product in the manufacture of soap, hard candles and lead plaster. 
The fats are also decomposed when exposed to the action of steam 
at from 500° to 600° F. (260° to about~315° C.) glycerin and oleic, 
palmitic, or stearic acid being formed. 

Properties. — Glycerin, {Glycerinum, U. S. P.) is a viscid liquid 
of sp. gr. 1.246 ; it has a sweet ta^te, and is soluble in water or 
alcohol in all proportions. It has remarkable powers as a solvent, 
is a valuable antiseptic even when diluted with 10 parts of water, 
and is useful as an emollient. Under reduced pressure it may be 
distilled unchanged, but at ordinary atmospheric pressure it under- 
goes partial decomposition on distillation. In a shallow open 
vessel heat readily vaporizes it if a little water be present. From 
damp air glycerin absorbs moisture slowly, but in considerable 
proportions. Perfectly pure and anhydrous glycerin, at a few 
degrees below the freezing point of water, sometimes solidifies to 
a mass of crystals. 

Tests. — Heat one or two drops of glycerin in a test-tube, 
alone or with concentrated sulphuric acid, acid potassium sul- 
phate, or other salt powerfully absorbent of water ; vapors of 
acrylaldehyde or acrolein (from acer, sharp, and oleum, oil) 
are evolved, recognizable by their powerfully irritating eflTects 
on the eyes and respiratory passages. If the glycerin be in 

1 It will be noticed that one of the names of each alcohol has the ter- 
mination -ol, carbinol, glycol, glycerol, saligenol, pyrogallol. 



438 ORGANIC CHEMISTRY. 

solution, the latter must be evaporated to as small a volume 
as possible before the test is applied. 

C3H,(OH)3 = 2H,0 + CH, : CH.COH 

Glycerin Water Acrylaldehyde 

To some dilute solution of borax, reddened by the addition 
of phenol-phthalein, add a few drops of a solution (neutralized 
if necessary) suspected to contain glycerin ; if any is present, 
the color will be discharged owing to the liberation of free 
boric acid, but will reappear on heating the solution; this 
reaction is also given by other poly-hydroxy alcohols, such as 
mannite or glucose. 

Add a few drops of the fluid suspected to contain the gly- 
cerin to a small quantity of powdered borax ; stir well together ; 
dip the looped end of a platinum wire into the mixture, and 
heat in the Bunsen flame ; a deep green color is produced 
(Senier and Lowe). 

The glycerin liberates boric acid, which colors the flame {see p. 
320). Ammonium salts, which similarly affect borax, must first 
be got rid of by boiling with solution of sodium carbonate. Acids 
must be neutralized. Liquids containing much indefinite organic 
matter must sometimes be evaporated to dryness, the residue 
extracted with alcohol, and the alcoholic extract tested for glycerin. 
To detect traces, liquids must be concentrated. 

Glycerin, by action of concentrated nitric acid, yields trinitrine, 
nitroglycerin, or glyceryl nitraie, Q.^.^i^O.^.^. It is highly explosive, 
a very small quantity being liable to explode during preparation, 
and with great violence. 75 parts of nitroglycerin absorbed by 
25 of porous silica, yield a pasty mass, more convenient to handle 
than nitroglycerin itself, which is used for blasting, under the 
name of dynamite. A one percent, solution of nitroglycerin in alco- 
hol is the Spiritus Glycerylis Natratis, U, S. P. 

Besides glycerin itself, there are several official preparations of 
glycerin — solutions of phenol and tannic acid and of borax in gly- 
cerin, and also a species of mucilage of starch in glycerin — Glyceri- 
tum Acidi Tannici, Glyceritum Amyli, Glyceritinn Boroglycerini, 
Glyceritum Ferri, Quinime et Strychnince Phosphatum, Glyceritum 
Hydrastis, and Glyceritum Phenolis. 

Fats and Oils. 

Processes of Extraction. — Fixed oils and fats are extracted from 
animal and vegetable substances by pressure or straining, with or 
without the aid of heat, or by digestion in solvents, as ether, etc., 
and evaporation of the solvent. 



FATS AND OILS. 



439 



Constitution a7id General delations. — Fixed oils and fats are ether- 
eal salts or esters, and the metallic salts (soaps), obtained from them 
by the action of metallic hydroxides (by saponification), are quite 
comparable with the salts of other organic acids. Just as potas- 
sium acetate, KCgHgOg, is a compound of potassium (K) with the 
acid radical of the acetates, (C2H3O2), so soft soap is a compound 
of potassium with the acid radical of the oleates (C^gH^gOg), and 
hence is chemically termed potassium oleate, KC^gHggO. Olive 
oil {Oleum Olivce, U. S. P,), from which soap is officially prepared, 
is mainly oleate of the trivalent radical glyceryl^ (C3H5) ; the form- 
ula of this oleate is C^^{Q^Jl„fi^)^, and its name oleine. The for- 
mation of a soap, therefore, on bringing together oil and a moist 
oxide or hydroxide, is an ordinary case of double decomposition, 
as seen already in connection with lead plaster (p. 224), or as illus- 
trated in the following equation representing the formation of com- 
mon hard soap : — 



3NaOH + Q^^^{Q^J1.^^0, 

Sodium Glyceryl oleate 

hydroxide (vegetable oil) 
(caustic soda) 



3NaC,gH3302 

Sodium oleate 
(hard soap) 



+ C3H,(OH)3 

Glyceryl 
hydroxide 
(glycerin) 



Berthelot has succeeded in preparing oil artificially fi-om hydro- 
gen oleate, or oleic acid, HC^gH3302, and glycerin ; and it is said to 
be identical with the pure oleine of olive oil and of other fixed oils. 

Olive oil is liable to contain cotton-seed oil, itself a good oil, but 
cheaper than olive oil ; it may be detected by Becchi' s test. The 
following are the official directions for carrying out the test : — If 
5 Cc. of the oil be shaken with 5 Cc. of a reagent prepared by dis- 
solving 0.1 gramme of silver nitrate in 10 Cc. of alcohol, with the 
addition of two drops of nitric acid, no dark color should be pro- 
duced when the mixture is heated on a water-bath for five min- 
utes. 

Hard fats consist chiefly of stearine — that is, of glyceryl tristear- 
ate, 03115(0^3113.02)3. Mr, Wilson, of Price's Oaiidle Company, 
obtained stearic and oleic acids and glycerin by simply passing 
steam, heated to 500^ or 600° F. (260° or 315.5° C), through 
melted fat. Both the glycerin and the fat-acids distil over in the 
current of steam, the glycerin dissolving in the condensed water, 
the fat-acids floating on the aqueous liquid. From glyceryl ole- 
ate and steam there result hydrogen oleate (oleic acid) and glyceryl 
hydroxide (glycerin).^ The oleic acid {Acidum Oleicmn, U. S. P.) 
is separated by cooling and pressing the mixture. It is a straw- 
colored liquid, nearly odorless and tasteless, and with not more 

' Any such decomposition of water and fixation of its elements, whether 
direct as above, or indirect through the intermediate agency of saponifica- 
tion, is termed hydrolysis (vSiop, hudur, water, Auco, bio, I decompose). The 
fixation of water without such actual separation of its elements from each 
other is termed hydration. 



440 ORGANIC CHEMISTRY. 

than a faint acid reaction. Unduly exposed to air, it becomes brown 
and decidedly acid. Sp. gr. 0.890 to 0.910. It is insoluble in 
water, but readily soluble in alcohol, chloroform, and ether. At 
40° to 41° F. (4.5° to 5° C), it becomes semi-solid, melting again 
at 56° to 60° F. (13.3° to 15.5° C). It should be completely saponi- 
fied when warmed with potassium carbonate ; and an aqueous 
solution of the resulting salt, neutralized by means of acetic acid 
and treated with lead acetate, should yield a precipitate which, 
after washing with boiling water, is almost entirely soluble in ether, 
showing the absence of any important quantity of stearic and pal- 
mitic acids, lead stearate and palmitate being insoluble in ether. 

In a mixture of oils or fats and free fatty acids, the latter may 
be determined by taking advantage of their solubility in alcohol, 
and the formation of a neutral soap on shaking the alcoholic solu- 
tion with sodium hydroxide, phenol-phthalein being used as indi- 
cator. {See the section on the use of standard sodium hydroxide 
solution in volumetric analysis.) 

The author found, Pharmaceutical Journal, March, 1863, that 
oleic acid readily combines with alkaloids and most of the metallic 
oxides or hydroxides forming oleates which are soluble in fats. In 
this way active medicines may be administered internally in con- 
junction with oils, or externally in the form of ointments. Ole- 
'atum AtrophifB, U. S. P., Oleatwn Cocalnce, U. S. P., Oleatum 
Veratrince, U. S. P., Unguentum Hydrargyria U. S". P. Tichborne 
considers the formula of mercuric oleate to be Hg(CjgH3302)2, H^O. 

Some fats, such as " suint" from sheep's wool, and the unctuous 
matter from bristles, feathers, horn, and hair generally, yield by 
saponification, etc., fatty acids and, instead of glycerin, cliolesterin, 
GgyH^-OH, a crystalline monatomic alcohol. The "lanoline" of 
pharmacy is cholesterin fat which has absorbed a large volume of 
water. 

Wool Fat (Adeps Lance, U. S. P.) is the purified cholesterin- 
fat of sheep's wool. It is a yellowish, tenacious, unctuous mass ; 
almost inodorous ; melting-point about 104° F. (40° C.) ; readily 
soluble in ether or in chloroform, sparingly soluble in alcohol. 1 
gramme should dissolve almost completely in 75 cubic centimetres 
of boiling alcohol, the greater part separating in flocks on cooling. 
When incinerated with free access of air, it leaves not more than 
0.3 percent, of ash, which should not be alkaline to litmus. 2 
grammes dissolved in 10 Cc. of ether, two drops of phenol-phtha- 
lein T. S., being added, should with one drop of normal potas- 
sium hydroxide V. S., produce a deep red color (limit of acidity). 
Its solution in chloroform poured gently over the surface of sul- 
phuric acid acquires a purple-red color. Heated with potassium 
hydroxide T. S., no ammoniacal odor should be evolved (absence 
of organic nitrogenous matter). 

Hydrous Wool Fat (Adeps Lance Hi/drosus, U. S. P.) is an inti- 
mate mixture of 7 parts of wool fat with 3 of water. It is com- 



^6»yiP*S'. 441 

monly known as ''Lanoline." It is yellowish white ; free from 
rancid odor. When heated it separates into an upper oily, and a 
lower aqueous, layer. 10 grammes heated on a water-bath, with 
stirring, until the weight is constant, should yield not less than 
7 grammes of residue, which should answer to the tests for Adeps 
Lance. 

Soaps. 

Linseed oil boiled with solution of potassium hydroxide yields 
potassium soap, or soft soap [Sapo Mollis, U. S. P.) ; with sodium 
hydroxide, sodium soap, or hard soap {Sapo, U. S. P. is prepared 
from sodium hydroxide and olive oil), or white Castile soap, as dis- 
tinguished from the variety of hard Castile, or Marseilles soap, 
which is "mottled" by iron soap; mixed with lime-water, calcium 
soap Linimentum Calcis, U. S. P. ), while an ammonium soap, (Lirii- 
menfum ammonice, U. S. P.), may be made by mixing ammonia 
water, alcohol, cotton-seed oil and oleic acids, — all containing 
oleates, chiefly, of the respective metallic radicals. Their mode 
of formation is indicated in the equation on p. 439. The alkali- 
rhetal soaps are soluble in alcohol, the others insoluble. • Linimen- 
tum Saponis and Linimentum Saponis Mollis are official. A green 
soap, much used on the continent of Europe, and, indeed, official 
in Germany (formerly as Sapo Viridis, now as Sapo Kalinus 
Venalis), is made by adding indigo to ordinary soft soap; the 
yellow color of the soap yielding with the indigo a greenish com- 
pound. Curd Soap is a soap made with sodium hydroxide and a 
purified animal fat consisting principally of stearin. It will, of 
course, chiefly contain sodium stearate. In pharmacy it is often 
advantageously employed instead of the "hard soap." 

The hard soap met with in commerce is made from all varieties 
of oil, the commoner kinds being simply the product of the evapo- 
rated mixture of oil and sodium hydroxide, while the better sorts 
have been separated from alkaline impurities and from the glycerin 
produced on boiling the oil with sodium hydroxide lye, by the addi- 
tion of common salt, or of excess of lye, to the liquors, which causes 
the precipitation of the pure soap as a curd. Potassium soajo is not 
so readily precipitable by salt; moreover, some sodium soap results. 
Saponification on the small scale is much facilitated by first well 
mixing the oil with 5 percent, of sulphuric acid, and letting this 
mixture stand for twenty-four hours. The dark product is then 
readily soluble when boiled with sodium hydroxide, and the clear 
liquid yields a crust of white soap on cooling. If required quite fi-ee 
from alkali, the resulting soap is boiled with water until dissolved, 
salt is added, and the whole cooled. A cake of pure soap results. 

The cleansing action of soap is really the cleansing action of a 
dilute solution of alkali, a small quantity of soap interacting with 
a large quantity of water to form acid stearates and palmitates, 



442 ORGANIC CHEMISTRY. 

and even acid oleates after a time, which separate from the solution, 
and free alkali, which remains in solution. 

• Yellow soap is a common, cheap soap, containing a good deal 
of resin soap, resin consisting chiefly of acids — pinic, sylvic, 
pimaric, etc. — which readily interact with alkalies to form true 
soaps. 

Saponification. — This term is now extended in chemistry so as 
to include any process analogous to the foregoing — any reaction 
in which an alkali decomposes an ethereal salt or alkyl salt (ester). 

Solid Fats. 

1. Lard { Adeps, U. S. P.) is the purified internal fat of the 
abdomen of the hog — the perfectly fresh omentum or flare, freely 
exposed to the air to dissipate animal odor, rubbed to break up 
the membranous vesicles, melted at about 130° F. (54.4° C), and 
filtered through paper or flannel. 2. Benzoinated Lard {Adeps 
Benzoinatus, U. S. P.) is lard heated over a water-bath with ben- 
zoin (fifty parts to one), which communicates an agreeable odor 
and prevents or retards rancidity. Purified lard is a mixture of 
oleine and stearine. Margarine, formerly supposed to be a con- 
stituent of lard and other soft fats, is now regarded as a mere 
mixture of palmitine (the chief fat of palm-oil) and stearine. 
3. Suet, the internal fat of the abdomen of the sheep, purified by 
melting and straining, forms the oflicial Prepared Suet ( Sevum 
Prceparatum, U. S. P.) ; it is almost exclusively composed of 
stearine, or glyceryl stearate, C3H5(CjgH.^.02)3. Tallow is chiefly 
mutton-fat and beef- fat, but may contain other animal fats; some 
vegetable fats also are termed tallow. 4. Expressed oil oi Nut- 
meg, commonly but erroneously termed Oil of Mace, is a mixture 
of a little volatile oil with much yellow and white fat ; the latter 
is myristin or glyceryl myristate, €3115(0^^112.02)3. 5. Oil of Theo- 
hroma, or Cacao butter {Oleum Tlieobromatis, IJ. S. P.), chiefly 
stearine, but with one higher and some lower homologues (Heintz), 
is a solid fat pressed from cocoa nibs the roasted and broken seeds 
of the Theobroma Cacao. The seeds contain from one-half to two- 
thirds of this fat. [Cocoa is too rich for use as food, hence it is 
diluted with farina (affording ^^ cheap cocoa^^) or sugar (affording 
chocolate) or has a portion of its fat extracted, while its solublity 
is, in certain brands, usefully increased by a process which results 
in a slight addition to the potassium salts of its ash, chiefly to the 
potassium phosphate.] 6. Cocoanut oil or butter, a soft fat con- 
tained in the edible portion of the nut of Cocos nucifera, or cocoa- 
nut of the shops, is a mixture containing glyceryl compounds of 
six acid radicals — namelv, those of caproic (C^Hj^Og), caprylic 
{C^YL^P^), rutic (C,oH^g02), lauric (C,2H2302), myristic (C,,H2,02), 
and palmitic (0,^113^02) acids — Avhich, like some acid radicals from 
resin, when united with sodium, form a soap differing from ordi- 



FIXED OILS. 443 

nary hard soap (sodium oleate) by being tolerably soluble in a 
solution of sodium chloride; hence the use of cocoanut oil and 
resin in making marine soap, a soap which for the reason just 
indicated, readily yields a lather in sea-water. 7. Kokum Butter, 
Garcinia Oil, or Concrete Oil of Mangosteen, a whitish or yellow- 
ish-white fat obtained from the seeds of Garcinia Indica or G. 
purpurea, is composed of stearine, myristicine and oleine. It is 
recognized in the old Pharmacopoeia of India {Garcinia^ purpurece 
Oleum). 

Butter commonly yields 87| percent, of insoluble fat acids on 
saponification and decomposition of the soap by acid. Other ani- 
mal fats, with which butter is likely to be adulterated, yield about 
95J. Hence the percentage of fat acids, and, especially, volatile 
acids, insoluble acids, and soluble acids, yielded by a suspected 
sample of butter, indicates purity or the opposite. Occasionally, 
however, a sample of genuine butter may not conform to the fig- 
ures, hence they cannot be relied on to show the exact extent of 
sophistication. 

Fixed Oils. 

Fixed and Volatile oils are naturally distinguished by their 
behavior when heated; they also differ in their chemical nature, a 
fixed oil being, as already stated, an ethereal salt, while a volatile 
oil is usually a hydrocarbon of some kind, mixed with a compara- 
tively small proportion of a substance — containing oxygen as well 
as carbon and hydrbgen — to which the odor of the oil is largely 
due. Substances of the latter kind are now articles of trade under 
the name of "concentrated essential oils." 

Drying and Non-drying Oils. — Among fixed oils, most of which 
are glyceryl oleate with a little palmitate and stearate, a few such 
as — 1. Linseed oil [Oleum Lini, U. S. P., contained in Linum, 
U. S. P., which when reduced to a coarse powder, is ground lin- 
seed), and 2. Cod-liver oil {Oleum Morrhuce, U. S. P.), and, to 
some extent, castor and croton oils, are known as drying oils, from 
the readiness with which they absorb oxygen and become hardened 
to a resin. Linseed commonly contains 37 or 38 percent, of oil ; 
25 to 27 percent, is obtained by submitting the ground seeds to 
hydraulic pressure, 10 to 12 percent, remaining in the residual oil- 
cake. Boiled oil is linseed oil which has been boiled with lead 
oxide. This treatment increases the already great tendency of lin- 
seed oil to resinify, forming linoxyn on exposure to air. The dry- 
ing oils appear to contain linoleine, an oily substance distinct from 
oleine. Cod-liver oil contains an unimportant trace of iodine, 1 
in one or two million parts, according to Stanford ; a little choline 
is found also, and other bases, Gautier and Mourgues having iso- 
lated aselline, CgjH.^.^N^, and morrhuiue, C,^H„.N3, besides butyl-, 
amy]-, and hexyl-amines and dihydro-lutidine. Among the non- 




444 ORGANIC CHEMISTRY. 

drying oils are the following : — 3. Almond oil {Oleum Amygdalce 
Krpressum, U. S. P.), yielded both by the bitter {Amygdala Amara, 
U. S. P.) and the sweet seed {Amygdala Dulcis, U. S. P.), to the 
extent of 45 and 50 percent, respectively. 4. Lycopodium {Lyco- 
podium, U. S. P.), a yellow powder composed of the spores of the 
common Club-Moss {Lycopodium clavatum), contains a large pro- 
portion of a very tluid fixed oil ; also an alkaloid (Bodeker), lyco- 
podine, C32H.,N203. 5. Oil of inale fern {Aspidium, U. S. P.), a 
vermifuge obtained by exhausting the rhizome with ether and 
removing the ether by evaporation — a dark-colored oil containing 
a little volatile oil and resin. Its active constituent appears to be 
filmaron, C^.H.^Ojg, a bright yellowish-brown powder, insoluble or 
sparingly soluble in water and alcohol, but easily soluble in ether, 
acetone, etc. By certain decompositions filmaron yields ^/icicaciV/, 
C\^H^gO-. The extract also contains flavaspidic acid, aspidinol, 
and other substances. 6. Fixed oil of mustard, a bland, inodor- 
ous, yellow or amber oil, yielding by saponification and action of 
sulphuric acid, glycerin, oleic acid, and erucic acid, ILCy^Jl^-fi^ 
(Darby). 7. Arachis oil is found to the extent of 40 or 50 percent, 
in the seeds of the Arachis hypogcEa, the Pea-nut, Ground-nut, or 
Earth-nut (so-called because the pod of the herb by the growth of 
its stalk downward if forced beneath the surface of the ground and 
there ripens). It is chiefly oleine, but contains hypogseine, palm- 
itine, and arachine. The oil is largely used in India in place of 
olive oil, and is becoming much employed in Europe, especially 
for soap-making. 8. Olive o\\ [Oleum Olivce, \J. S. P.), already 
noticed. 9. Shark-liver oil from Squalus carcharias, is used as a 
substitute for cod-liver oil in India. 10. Croton oil {Oleum Tiglii, 
U. S. P.). Geuther states that no such acid as crotonic is obtain- 
able from croton oil, but acetic, butyric, valeric, and higher mem- 
bers of the oleic series, together with tiglic acid, HCgll.O.^. H. 
Senier states that alcohol separates croton oil into a soluble oil con- 
taining the powerful vesicating principle of croton oil and an insolu- 
ble non-vesicating but powerftilly purgative principle. .Kobert 
states that free crotonoleic acid is both the vesicant and the purga- 
tive. 11. Sesame oil (Gingelly, Teal, or Benne Oil) from the seeds 
of Sesamum indicum, is also largely used in Europe. It has most 
of the characters of the best olive oil. It may be detected in olive 
oil by well shaking the sample with a solution of pyrogallol in con- 
centrated hydrochloric acid, and separating and boiling the acid 
liquid, a purplish color resulting if sesame oil be present. 12. 
Gynocardia oil or chaulmoogra oil, from the seeds of Gynocardia 
odorata {Chaulmugra). It consists of gynocardic, palmitic, hypo- 
gaeic, and cocinic glycerides, with some gynocardic and palmitic 
acids (Moss). 13. Castor oil {Oleum Ricini, U. S. P.) is chiefly 
glyceryl ricinoleate, 0.^11.(0,^,113303)3, or ricinoleine, a slightly oxi- 
dized oleine, soluble, unlike most fixed oils, in alcohol and in 
glacial acetic acid. Castor-oil seeds were stated, by Tuson, to con- 



I 



MANNITE. 445 

tain an alkaloid, ricinine, to which Beck gave the formula, 
Cg^H^gN^Og. Soave holds that ricinine is not an alkaloid and that 
its formula is C^^H^gN^O^. It possesses no purgative property. 
Castor-oil seeds also contain an albumose, ricin, resembling, 
physiologically, but not quite chemically, the abrin, of jequirity. 



Trihydric Alcohols, of the CjjB[2n._g(OH)3 series. 
Pyrogallol or Pyrogallic acid. — Trihydroxybenzene, CgH3(0H), 
{Pyrogallol,\],^.V.). (.S'ee p. 343). 



Polyhydric Alcohols. — Erythrite or Lichen Sugar, C^H^(OH)^, 
found in Protococcus vulgaris, Boccella tinctoria, and B./ucif or mis, 
is one of the few known tetrahydric alcohols. Quercite, the sugar 
of acorns, is pentahydric ; Mannite is hexahydric. Sorbite, which 
is also hexahydric, occurs in the fruits of the order Rosacece. 

Mannite, CgHg(OH)g. — Boil manna with 15 or 16 parts of 
alcohol, filter, and set aside ; mannite separates in colorless 
shining crystals or acicular masses, to the extent of from 60 to 
80 percent, of the manna. It is closely related to the ordinary 
sugars, fructose (levulose) yielding mannite by the action of 
nascent hydrogen (sodium amalgam) : — 

C.H„0, + 2H = C,H,.0, 

Fructose Hydrogen Mannite 

Mannite or mannitol does not undergo fermentation in contact 
with yeast. With nitric acid it forms explosive nitromannite, 
CeHg(N03),. 

Manna is a concrete saccharine exudation obtained by making 
transverse incisions in the stems of cultivated trees of Fraxinus 
Ornus. It occurs in stalactitic pieces, varying in length and thick- 
ness, flattened or somewhat concave and of a pale yellowish-brown 
color on their inner surface, and nearly white externally. This 
manna, which is known as flake manna, is crisp, brittle, porous, 
crystalline in structure, and readily soluble in about six parts of 
water. Odor faint, resembling honey ; taste sweet and honey-like, 
combined with a slight acridity and bitterness. It contains about 
10 percent, of moisture. Mannite is also met with in celery, onions, 
asparagus, certain fungi and sea- weeds ; it occurs in the exudations 
of apple-trees and pear-trees, and is produced during the viscous 
fermentation of sugar. When oxidized, it yields first the sugar 
termed mannose, CH,,OH(CHOH)^COH, then some mannonic acid, 
CH20H(CH0H),C00H, and finally saccharic acid, (CHOH),- 
(COOK),. 



446 



ORGANIC CHEMISTRY. 



Dulcite, isomeric with mannite, is formed by the action of sodium 
amalgam pn galactose (from milk sugar). It differs from mannite 
by yielding mucic acid, (CH0H)^(C00H)2, isomeric with saccharic 
acid, when oxidized with nitric acid. 



QUESTIONS AXD EXERCISES. 
Describe the process for the preparatiou of ether, giving equations. — 
How is commercial ether purified ? — How is phenol artificially and com- 
mercially prepared ? — How would you distinguish phenol from creosote? 
— Give the formulae and systematic names for picric acid, sodium car- 
bolate, and resorcinol. — Give names for the substances having the formulae 
C6H4OH.CH3 and C6H5CH2OH. — What are glycols and how are they pre- 
pared? — Give formula and mention the chief properties of gyceriu. — 
What is the specific gravity of glycerin ? — By what tests is glycerin 
recognized? — Enumerate some official preparations in which glycerin is 
employed. — Give a sketch of the general chemistry of fixed oils, fats and 
soaps.— What is the difierence between hard and soft soap? — Which soaps 
are official? — Name the source of lard. How is ^^Adeps, U. S. P.," obtained? 
— Mention the chief constituents of suet. — Whence is cacao-butter 
obtained ? — Why is marine soap so-called, and from what fatty matter is 
it almost exclusively prepared ? — What do you understand by dryincj and 
non-drying oils? — In what respect does castor oil difier from other oils? — 
Classify pyrogallol {PyrogaUic acid), erythrite, mannite, and dulcite. — 
Describe the source and characters of manna. 



ALDEHYDES AND ACIDS. 

Aldehydes and acids may be formed by the oxidation of the 
primary alcohols, glycols, etc. Monohydric alcohols, having 
only one hydroxyl (OH) group, form monobasic acids, dihydric 
alcohols (glycols) having two hydroxyl groups, yield monobasic 
and dibasic acids: and so on. Thus: — 



CH3CH2OH 

Ethyl alcohol 



CH^OH 



r yields 



CH3COH 

Acetaldehvde 



) J CH3COOH 

I ^lld I Acetic acid 



CH.OH 

Glycol 
or 
Ethylene glycol 



yields CH,OH ^ 



COH 

Glycolaldehyde J 



)- <! 



and 

also 



COH 

I 
COH 

Oxalaldehyde 
or Glyoxal 



and 



and 



f CH3OH 

I I 

j COOH 

I Glycollic 



acid 



COOH 

I 
COOH 

Oxalic acid 



It will be seen that the groups COH and COOH denote respectivehj 
an aldehyde and an acid, the H in the COOH group being replace- 
able by a metal, as in the case of CH3.CO.OXa (sodium acetate). 



ALDEHYDES AND ACIDS. 447 

Acids may also be obtained by acting on the nitriles'^ (or cyan- 
ides of the hydrocarbon radicals, with hydrochloric acid and 
water. Thus: — 



CH3CN + 


2HP 


+ HCl = 


CH3COOH 


+ HN.Cl 


Acetonitrile 


Water 


Hydrochloric 
acid 


Acetic acid 


Ammonium 
chloride 



Many aldehydes and acids occur in nature; for example, oil of 
meadow-sweet (salicylaldehyde), oil of bitter almonds (benzalde- 
hyde), tartaric acid, citric acid, etc. 

General Reactions. — Aldehydes form crystalline compounds 
with acid potassium sulphite; by oxidation they yield acids, and 
by the reducing action of nascent hydrogen they yield alcohols; 
while acids yield aldehydes and then alcohols by reduction with 
nascent hydrogen. With oxides, hydroxides, carbonates, and 
sometimes with metals, acids form metallic derivatives (salts). With 
the alcohols, acids yield alkyF or ethereal salts, as, for instance, 
acetic ether. By the action of the chloride, iodide, or bromide 
of phosphorus their hydroxyl group is replaced by chlorine, 
iodine, or bromine: — 

3CH3COOH + PCI3 = 3CH3CO.CI + PO3H3 
Acetic Phosphorus Acetyl Phosphorus 

acid trichloride chloride acid 

Like inorganic acids, they form anhydrides by the elimination of 
water: — 

2CH3COOH - H,0 = cH3Co}^ 
Acetic acid Water Acetic anhydride 

The important aldehydes and acids will now be mentioned. 

1 The uitriles may be prepared by the interaction of the halogen deriva- 
tives of the hydrocarbons with potassium cyanide — : 

CH3CI + KCN = CH3CN + KCl 

Methyl Potassium Methyl cyanide Potassium 

chloride cyanide or acetonitrile chloride 

The reactions of nitriles indicate that the hydrocarbon radical is united 
to the carbon of the cyanogen group. In the isomeric substances called 
isonitriles or carbnmines (obtained by the interaction of the halogen deriva- 
tives of the hydrocarbons with silver cyanide) the hydrocarbon radical 
appears to be united to the nitrogen of the cyanogen group. 

■^ Alkyl Salts. Alhjl, from the Arabic article «Z,the, as in alkali, alcohol, 
etc., and the termination common to the names of such radicals as etliyl. 
arayl, and phenyl, and as seen in methyl, the prototype of such names. 
In Germany the word ester (see p. 401), a mere variation of the word ether. 
is similarly employed. In the scientific chemistry of both countries it is 
thus sought to restrict the name ethers to the organic radical oxides, as 
common ether, (C2H5)20 [Mher, U. S. P.). 



448 ORGASIC CHEMISTRY. 

The Acetic Series of Monobasic Acids, QJl.^^.Q 0.0^. 

These acids are formed by the two general methods given, 
namely, from primary alcohols of the ethyl series and from cyan- 
ides of the paraffin hydrocarbon radicals. 

Formic Acid, H.COOH. See i^. 324. 

Formaldehyde, H.COH, is obtained by passing a mixture of 
methyl alcohol vapor and air over a heated spiral of metallic copper. 
At ordinary temperatures it is a gas which dissolves readily in water. 
An aqueous solution of formaldehyde, commercially known as 
"formalin,"' is largely used as an antiseptic and disinfectant. 
This Solution of Formaldehyde [Liquor Formaldehydi, U.-S. P.), 
contains about 40 percent, of formaldehyde, HCOH, and is a 
liquid of suffocating odor. When evaporated over sulphuric acid, 
a polymeride, C3Hg03, jjaraforrnaldehyde, is formed ; and when 
allowed to remain in contact with lime-water, another polymeride, 
CgH^^Og, formo-se, is produced, which is a mixture of sugars. This 
polymerization of an aldehyde is of interest as suggesting methods 
for preparing sugars by synthesis. 

By the action of ammonia on formaldehyde, hexamethylenamine 
or hexamethylene-tetramine, (CH., igX^ {Hexamethylenamina, 
U. S. P.) is obtained. 

Acetic Acid, CH3COOH (Methyl-formic acid). Obtained by 
oxidizing ethyl alcohol and in other Avays. See p. 281. 

Aldehyde, or Acetaldehyde, C.^H^O, or CH^COH. 

Experiment. — Place together, iu a capacious test-tube (or 
flask), about four parts of potassium dichromate and twelve 
of water ; cautiously mix four parts of alcohol with five of 
concentrated sulphuric acid, and allow the mixture to flow 
slowly through a stopcock funnel on to the contents of the 
tube, and gently warm the mixture: aldehyde («/cohoI 
c/eAvf/rogeuatum), a highly volatile liquid, is immediately 
formed, and its vapor evolved, recognizable by its peculiar, 
somewhat fragrant odor. Adapt a cork and rather long 
bent tube to the test-tube, and let some of the aldehyde 
slowly distil over into another test-tube, the condensing-tube 
being kept as cool as possible. Set the distillate aside for a 
day or two ; the aldehyde will have nearly all disappeared, 
and acetic acid be found in the tube. Test the remaining 
liquid by means of litmus-paper ; it will be found to have an 
acid reaction ; make it slightly alkaline by adding a drop or 
two of solution of sodium carbonate, then boil to remove any 
alcohol and aldehyde present, add sulphuric acid, and notice 
the characteristic odor of the acetic acid eyolved^ .' 

These experiments will render the process of oxidation de^ 
scribed in connection with acetic acid more easily understood. 



ALDEHYDES AND ACIDS. 449 

Pure diluted alcohol is not oxidized by exposure to air alone ; but 
in presence of the ferment, Mycoderma aceti, it is oxidized first to 
aldehyde and then to acetic acid. 

In the above process the potassium dichromate and sulphuric 
acid furnish nascent oxygen, which then acts on the alcohol (just 
as in presence of the ferment mentioned above, the oxygen of the 
air acts on the alcohol in fermented infusion of malt, and in beer 
or wine), giving aldehyde : — 

SCHgCHpH + K^Crp, + 4H^S0 

Alcohol 

- 3CH3COH + K,SO, + Cr,(S0,)3 + 7Hp 
Aldehyde 

The aldehyde rapidly, even when pure (more rapidly when impure), 
absorbs oxygen and yields acetic acid : — 

2CH3COH 4- O2 = 2CH3COOH 
Aldehyde Oxygen Acetic acid 

The aldehyde from the above reaction may be mixed with twice 
its volume of ether, placed in a bottle surrounded by ice, and 
saturated with dry ammonia; a crystalline coi pound, aldehyde- 
ammonia, CH.^.CH.0H.NH2, separates. Pure aldehyde may be 
obtained from this by distilling with dilute sulphuric acid. 

Tests. — Aldehyde heated with solution of potassium hydrox- 
ide gives a brownish-yellow resinous mass of peculiar odor. 
Its aqueous solution reduces silver salts, giving a mirror-like 
coating to the inside of a test-tube. When acted on by phenol 
dissolved in sulphuric acid, it gives a red color. Aldehyde 
on keeping, or in contact with sulphuric acid, zinc chloride, 
etc., yields two polyraerides — metaldehyde, ;rC2H^0, and 
paraldehyde, C^H^fi.^, the latter having a characteristic odor. 
Paraldehyde {Paraldehydum, U. S. P.) boils at 253.4° to 
257°F. (123° to 125°C.), dissolves in water, alcohol, or ether, is 
neutral, and should not become colored on standing for two 
hours with solution of potassium hydroxide (absence of alde- 
hyde). It may be congealed to a clear crystalline mass which 
melts at 51° F. (10.5° C). 

Chloral. 

Chloral, or trichloraldehyde, CC1...C0H, is a chlorine substitu- 
tion derivative of aldehyde, although it cannot directly be obtained 
by acting on aldehyde with chlorine, because condensation pro- 
ducts are formed. 

Experiment. — Pass a rapid current of dry chlorine into 
pure absolute alcohol so long as absorption occurs. During 
29 



450 ORGANIC CHEMISTRY. 

the first hour or two the alcohol must be kept cool, and after- 
ward gradually warmed till ultimately the boiling-poiut is 
reached. The crude product is mixed with three times its 
volume of sulphuric acid and distilled, again mixed with a 
similar quantity of sulphuric acid and again distilled, and 
finally rectified from quicklime. 

In the formation of chloral it would seem that the substances 
first formed are hydrochloric acid and aldehyde, the latter of 
which instantly combines with alcohol to form acetal: — 

CR^CH^OH + CI., = CH,COH -]- 2HC1 

Alcohol Chlorine Aldehyde Hydrochloric acid 

CH3COH .+ SC^H-OH = CHg.CH.COC^H,), + H^O 

Aldehyde Alcohol Acetal Water 

Acetal ^ by further chlorination yields trichloracetal: — 
CH3.CH(0C,H.), -f 3C1, = CCl3CH.(OaH,)2 + 3HC1 

Acetal Chlorine Trichloracetal Hydrochloric 

acid 

Trichloracetal when acted on by the hydrochloric acid yields 
ethyl chloride and chloral aicoholate: — 

CCl3CH<^^A _!_ HCl = CCl3CH<^^A +C2H5CI 

Trichloracetal Chloral aicoholate Ethyl chloride 

From the aicoholate, trichlor-aldehyde or chloral is liberated by 
treatment with sulphuric acid: — 

CC1,.CH. (0G2H,)0H+H,S0, = CCl.COH+C^H.HSO.+ Hp , 

Chloral aicoholate Sulphnric Chloral Ethyl-hydrogen Water 

acid sulphate 

Properties. — Chloral is a colorless liquid, of oily consistence. 
Sp. gr. 1.502. Boiling-point 201.2° F. (94° C ). Its vapor has 
a penetrating smell, and is somewhat irritating to the eyes. When 
mixed with water, heat is disengaged, and solid, white, crystalli- 
zable, hydrated chloral CCl3CH(OII)2 {Chloralum hydrahim, 
U. S. P.), also called Chloral Hydrate, results. ''Hydrated 
Chloral" is a true glycol, is systematic name being trichlorethyl- 
idene glycol: — 

C.,H,(OH), CC1,CH(0H), 

Ethylene glycol Trichlorethylidene glycol 

Hydrated chloral fi.ises easily when heated, solidifies, at about 
120° F. (48.9° C), boils at' from 202° to 206° F. (94.4° to 

1 Methjlal. — CH2(OCH3)2 the lowest member of the series, is occasion- 
ally used as a soporific. 



CHLORAL HYDRATE. 451 

96.7° C). It sublimes as a white crystalline powder, l^otli 
chloral and hydrated chloral are soluble in water, alcohol, ether, 
chloroform and oils. Oils and fats are also soluble in hydrated 
chloral. The aqueous solution should be neutral, and should give 
no reaction with silver nitrate. Chloral, especially if it contains 
a trace of acid, may undergo a spontaneous change into an opaque 
white isomeric modification, metachloral, insoluble in water, 
alcohol, or ether, but convertible by prolonged contact with water, 
or by distillation, into the ordinary condition. By action of 
dilute alkalies chloral yields alkali-metal formate and chloro- 
form : — 

CCI3COH + KOH = H.CO.OK + CHCI3 

Chloral, or rather concentrated aqueous solution of hydrated 
chloral (3 in 4), injected beneath the skin yields chloroform, 
and produces narcotic effects (Liebreich, Personne). Chloroform 
itself admits of similar hypodermic use (Richardson). If admin- 
istered by the stomach, thirty to eighty grains of solid hydrated 
chloral are required. The final products of the reaction of the 
chloroform and blood are sodium formate and chloride. A con- 
centrated alcoholic solution of potassium hydroxide effects an 
analogous change i—CHCls + 4K0H = H.COOK + 3KC1 + 

m^o. 

By the oxidizing action of nitric acid, hydrated chloral is con- 
verted into trichloracetic acid, CCI3COOH, {Acidum Trichlor- 
aceticum, U. S. P.), a white crystalline solid. Ammonia water 
and moist calcium hydroxide, as well as weak solutions of 
fixed alkalies, hydrated chloral into a metallic formate and chloro- 
form. The reaction with the slaked lime being especially definite 
and complete (Wood), it may be employed in ascertaining the 
quantity of hydrated chloral in a sample of the commercial article. 

2CCl3CH(OH)2 + Ca(0H)2 = 2CHCI3 + (HCOO),Ca + 2H,0 



2X164.12 2X11845 

From the foregoing equation and molecular weights, it is 
obvious that 100 grains of hydrated chloral, if quite dry, will 
yield by distillation with 30 grains of slaked lime and an 
ounce of distilled water (in a small flask with a long bent 
tube kep-t cool by moistened paper), 72.17 grains of chloro- 
form by weight or (the sp. gr. of chloroform being taken at 
1.493), about 52 minims. 

Small quantities of hydrated chloral in dilute solutions may bo 
determined by converting its chlorine into a soluble chloride by 
treatment with zinc and acetic acid, and titrating with volumetric 



452 ORGANIC CHEMISTRY. 

solution of silver nitrate (Short). A quantity of solution con- 
taining not more than 0,05 gramme is placed in a small flask with 
granulated zinc and acetic acid, and allowed to stand twenty-four 
hours; the solution is then poured off and the zinc washed two or 
three times with distilled water, a little potassium chromate added. 
It is then titrated with tenth-normal silver nitrate solution in the 
usual way, the acetic acid and zinc acetate not interfering with 
the indications. 1000 Cc. of the silver solution indicate 5.47 of 
hydrated chloral. 

Pure Hydrated Chloral. — Liebreich, who first proposed the use 
of hydrated chloral, gives the following as the characteristics of 
the pure article: — Colorless, transparent crystals. Does not decom- 
pose by the action of the atmosphere, does not leave oily spots 
when pressed between blotting-paper, affects neither cork nor paper. 
Smells agreeably aromatic, but a little pungent when heated. 
Tastes bitter, astringent, slightly caustic. Seems to melt on rub- 
bing between the fingers. Dissolves in water like candy without 
first forming oily drops; and the solution is neutral or faintly acid 
to test-paper. Dissolves in carbon bisulphide, petroleum, ether, 
water, alcohol, oil of turpentine, etc. Its solution in chloroform 
gives no color when shaken with sulphuric acid. Boiling-point 
203° to 205° F. (95° to 96.1° C). It volatilizes without residue. 
Distilled with sulphuric acid, the chloral should pass over at 205° 
to 207° F. (96.1° to 97.2° C). It melts at 133° to 136° F. (56° 
to 57.7° C), again solidifying at about 120° F. (48.8° C). Gives 
no chlorine reaction on treating the solution in water (acidulated 
with nitric acid) with silver nitrate. 

Impure Hydrated Chloral. — Yellowish, cloudy. Decomposes; 
leaves spots when pressed between blotting-paper; attacks corks 
and the paper of the packing. Has a pungent and irritating 
smell; on opening the bottle is sticky and often emits fumes. 
Taste strongly caustic. With water forms oily drops or is partially 
insoluble. Boils at a higher temperature. On treatment with 
sulphuric acid it turns brown, with liberation of hydrochloric 
acid. Gives chloride reaction on treating the solution in water 
(acidulated with nitric acid) with silver nitrate. 

Chloralformamide, {Chloralformamidum, U. S. P.), CCl^CHOH, 
NH.COH, is a crystalline solid produced by the direct union of 
anhydrous chloral and formamide. 

Chloralose, CgH^^Clg O^, is a derivative of chloral, prepared by 
heating together anhydrous chloral and glucose, then extracting 
with ether, and repeatedly distilling with water. 

Chloral alcoholates are obtained on combining alcohols with 

chloral. Chloral alcoholate or trichlorethylidene ethyl ether, 

OTT 
CCl3CH<^^ TT is obtained by mixing alcohol with chloral, it 

is in fact "hydrated chloral" with one hydroxyl group replaced 
by(OaH,). 



BROMAL: BUTYL CHLORAL. 



453 



Hirsclisohii's test for chloral alcoholate in hydrated chloral is 
as follows: — Add to 1 gramme of hydrated chloral 1 Cc. of nitric 
acid of sp. gr, 1.38; in the presence of chloral alcoholate yellow 
vapors or a yellow liquid will result at ordinary temperatures, 
or on warming. 

Bro7nal, CBrgCOH, hromal hydrate, CBr3CH(OH)2, and bromal 
alcoholates, are produced when bromine is employed instead of 
chlorine in the interaction with alcohol. lodal, CI3COH, is also 
known. 

Butyl Chloral, CaH^Cl^COH, originally, but erroneously, 
termed croton chloral, is a product of the action of dry chlorine 
on cold aldehyde. Butyl-chloral hydrate or hydrous butyl chloral 
(wrongly called croton-chloral hydrate), C3H^Cl3CH(OH)2 {tri- 
chlorbutylidene glycol), occurs in pearly white trimetric laminge, 
having a pungent but not acrid odor, and an acrid nauseous taste. 
It fuses at about 172°F. (77.8° C. ) to a transparent liquid, which, 
in cooling, commences to solidify at about 160° F. (71.1° C). 
Soluble in about 50 parts of water, and in its own weight of 
glycerin or of alcohol (90 percent.); it slowly dissolves in 20 
parts of chloroform. The aqueous solution is neutral or but 
slightly acid to litmus. It does not yield chloroform when heated 
with solution of potassium hydroxide or with milk of lime (absence 
of chloral hydrate). 

T/ie Acetic Series of Acids — Continued. 

Propionic Acid (ethyl-formic acid), CgH.COOH, is produced by 
oxidation of propyl alcohol. 

Butyric Acid (propyl-formic acid), Cgll^COOH, is formed by 
general methods ; also during the fermentation of cheese. It is 
found as a glyceryl salt in butter (whence the name butyric acid). 

Valeric Acid or Valerianic, C^HgCOOH. There are several 
isomeric varieties of this acid, the valeric acid from valerian and 
angelica root, and that artificially formed from amyl alcohol 
{see p. 425) being isovaleric acid, or isopropylacetic acid, 
CII(CH3)2CH2. COOH, the normal acid having the constitution 
CH3CH2CH2CH2.COOH. 

Palmitic Acid, Cj.H3,C00H, fromfats ; stearicacid, C,,H,.COOH, 
{Acidum Stearicum, U. S. P. ), from suet ; cei^otic acid, Cg^H. .,00011, 
from beeswax ; and melissic acid, CggH^jjCOOH, from beeswax and 
from carnauba wax (from the surface of the leaves of Copernicla 
cerifera, a Brazilian palm), belong to the acetic series. 



The Lactic Series. 

Acids of the Lactic Series, C„H,n(OH)COOH. 
embraces hydroxy-derivatives of the acetic series, 
hydrogen being replaced by the hydroxyl group. 



—This series 
one atom of 



454 ORGANIC CHEMISTRY. 

CH3COOH CH^lOHjCOOH 

Acetic acid Hydroxyacetic or glycollic acid 

Though they possess only one carboxyl (COOH) group, yet, 
having an alcoholic hydroxy 1 group, they may sometimes have 
two of their hydrogen atoms replaced by metals. 

They are best formed by hydrolysis of the nitriles produced by 
the union of hydrocyanic acid with aldehydes or ketones ; also by 
partial oxidation of glycols with dilute nitric acid ; and by acting 
on monochloro-derivatives of the acids of the acetic series with 
moist silver oxide : — 

2CH2CI.COOH + Ag,0 + H2O = 2CH2OH.COOH + 2AgCl 
Monoehloraeetic acid Glycollic acid 

Carbonic Acid or Hi/droxyformic Acid, OH. CO. OH, the first 
of this series, has been studied already. Carbamide or Urea, 
NH2.CO.XH2, the diamide of carbonic acid, is interesting his- 
torically as being the first organic compound synthetically pro- 
duced from inorganic sources {see p. 370). The acid amide of 
carbonic acid, car bamic acid, NHg.CO.OH, occurs as an ammonium 
salt, NH2.CO.ONH4, in the ammonium carbonate of pharmacy. 
Ethyl carbamate or Urethane, NH^.CO.OC^H., {^thylis Car- 
bamas, U. S. P.) is a mild hypnotic. 

Glycollic Acid (Hydroxyacetic acid), CHgOH.COOH, is found 
in the leaves of the Virginia Creeper ; artificially it may be obtained 
by carefully oxidizing glycol, and by the action of silver oxide on 
dextrose and fructose. 

Lactic Acid (Hydroxypropionic acid), C2H^(0H)C00H. Several 
isomeric hydroxypropionic acids are known; the lactic acid of fer- 
mentation (so-called ethylidene* lactic acid), CH3CH.(0H)C00H, 
and sarcolactic acid, from flesh, being those of technical importance 
{see p. 832). 

The Acrylic Series. 

Acids of the Acrylic Series, CnH2n_iC00H. 

Acrylic Acid, C^H^COOH, or CH, : CH.COOH, is formed by oxi- 
dizing acrolein (acrvlaldehyde, see Glvcerin) with silver oxide. 

Crofonic Acid, CgH.COOH, or CH3CH : CH.COOH, formerly 
supposed to be a constituent of croton oil, may be formed by oxi- 
dizing croton-aldehvde, and by acting on allvl cyanide, CgHgCN, 
with water and hydrochloric acid :— C3H5CN +^2H,0 -f HCl = 
CgH.CO.OH + NH.Cl. 

Oleic Acid, C^gHg^Og, is found as a glyceryl salt in many fats and 
oils. 

1 Substances having the CH3CH group are called ethylidene compounds. 
Compare hydrated chloral, trichloTethylide'/e glycol, CCIsCH.lOHJa. 



ACIDS OF ACETIC, LACTIC, GLYOXYLIC SERIES. 455 



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456 ORGANIC CHEMISTRY. 

Preparation of Oleic Acid. — Olive oil is saponified by means 
of potassium hydroxide and the resulting soap decomposed by 
tartaric acid, which liberates oleic and stearic acids. The oleic 
and stearic acids are heated with lead oxide, forming lead oleate 
and stearate, the former being dissolved out from the latter by 
ether. The ether is evaporated and the lead oleate treated 
with hydrochloric acid, which liberates oleic acid. 

Elaidlc Acid (isomeric with oleic acid) is formed by passing 
nitrogen peroxide into oleic acid; it is more stable than oleic acid, 
distilling unchanged. 

The Benzoic Series. 

Acids of the Benzoic Series, CnH^n.^COOH. — The acids of this 
series are formed by oxidizing hydrocarbons, by the oxidation of 
the corresponding alcohols, and by the hydrolysis of the correspond- 
ing nitriles. There are numerous isomers of all these acids, ben- 
zoic acid excepted. 

Benzoic Acid, CgH^COOH, [Acidani Benzoicuni, U. S. P.), occurs 
naturally in gum benzoin (Gum Benjamin), which contains from 
12 to 15 percent, the remainder of the '' gum " being mainly com- 
posed of two resins having the fonnulse C^QH^j-Og and CggH^QO.. 
Benzoic acid may be obtained by oxidizing benzaldehyde, 
CpHjCOH, which may be prepared from benzotrichloride {see p. 
409). Toluene, CpH.CH^, may be directly oxidized into benzoic 
acid, the methyl group (OH3) being resolved into COOH. Benzoic 
acid may also be produced by heating hippuric acid (benzoyl gly- 
cine or benzoyl glycocoll) with hydrochloric acid, p. 325. For 
other modes of obtaining benzoic acid artificially, see p. 321. Ben- 
zoic acid heated with lime yields benzene : — 

C„H,COOH + CaO = C,H, + CaCOg 

Benzoic acid Calcium oxide Benzene Calcium carbonate 

Benzaldehyde, CgH^COH (Benzaldehydum, U.S. P.), forms the 
greater part of oil of bitter almonds (see Amygdalin, p. 497). It is 
a colorless liquid, soluble in 30 parts of water, and in all propor- 
tions in ether and alcohol. Like other aldehydes, it forms a 
crystalline compound with acid sodium sulphite — in this case 
CeHj.COOH.NaHSO^. 

Benzoyl Chloride, C^HjOCl, results from the action of chlorine 
on benzaldehyde or of phosphorus pentachloride on benzoic acid. 
Benzaldehyde also results from the oxidation of the benzyl alcohol 
(C,H,OH) of balsam of Peru. 



HYDROXYBENZOW SERIES. 457 

The Hydroxyhenzoic Series. 

Acids of the Hydroxyhenzoic Series, C^Hgn-gOH.COOH. — Just 
as the acids of the lactic series are related to the acetic series, so 
are the acids of the hydroxyhenzoic (or salicylic) series related to 
the benzoic series. 

CH3COOH CH^H. COOH 

Acetic acid Hydroxyacetic or glycollic acid 

CgH^COOH CgHpH.COOH 

Benzoic acid Ortho-hydroxybenzoic or salicylic acid 

Salicylic OY Ortho-hydroxijbenzoic Acid, C^H^OH.COOH {Acidum 
Salicylicum, U. S. P.). Salicylic acid may be made by the oxida- 
tion of salicylaldehyde {vide infra). Sodium salicylate may be 
prepared by the action of carbonic anhydride on sodium-phenol 
(Kolbe). To accomplish this, phenol is mixed with sodium 
hydroxide, forming sodium-phenol, or sodium carbolate, CgHjONa. 
The sodium-phenol is then saturated with carbonic anhydride at 
the ordinary temperature, by which sodium phenyl carbonate is 
produced. The latter on being heated in closed vessels is trans- 
formed into sodium salicylate. From this salicylic acid may be 
obtained by the action of hydrochloric acid, and it may be purified 
by recrystallization from alcohol. It is identical with the natural 
acid. 

C.Hg.ONa -1- CO2 = C.H^O.CO.ONa 

Sodium-phenol Sodium phenylcarbonate 

C,H,O.CO.ONa = C.HpH.CO.ONa 

Sodium Sodium 

phenylcarbonate salicylate 

Salicylic acid, like phenol, is a powerful antiseptic but is free 
from the taste and smell of phenol. It is only slightly soluble in 
cold water, but readily soluble in hot water, alcohol, ether, and 
in aqueous solutions of such alkali-metal salts as borax, sodium 
phosphate, or potassium citrate, which it converts into acid salts 
with formation of a salicylate. A similar antiseptic cresofic acid 
(hydroxytoluic acid, C^H^OH.CH^.COOH) is similarly obtained 
from cresol or cresylic acid, C^H^OH.CH.^. Ferric chloride pro- 
duces a violet coloration with both salicylic and cresotic acids. 
Both acids have antipyretic properties. The alkali-metal salicy- 
lates, and probably therefore the cresotates, are very feeble anti- 
septics. Sodium salicylate [Sodii SaUcylas, U. S. P.), (NaC^H^CJ.,, 
H^O, made by neutralizing salicylic acid with sodium hydroxide 
or carbonate, forms small, colorless scales, or tabular crystals, 
soluble in alcohol, and readily soluble in water. Ammonium Sali- 
cylas {Ammonii Salicylas, U. S. P.), is a very similar salt. As phenol 
often contains cresylic acid, commercial salicylic acid may contain 
cresotic acid. An alcoholic solution of salicylic acid allowed to 



458 ORGANIC CHEMISTRY. 

evaporate spontaneously (exposure to dust being avoided), should 
leave a white residue free from color even at the points of the 
crystals. lodosalicylic acid, C^HglOs, and di-iodosalicyllc acid, 
C.H^l203, are used in medicine ; as also is acetylsalicylic acid, 

CgH^/ p^^TT , which is known as aspirin. 

Salicylaldehyde, or ortho-hydroxybenzaldehyde (salicylol, sali- 
cylousacid, salicyl hydride), CgH^OH.COH. — Found in the essen- 
tial oil of meadow-sweet {Spiroea ulmaria) ; also obtained by the 
oxidation of salicin. It may be artificially formed by the action 
of chloroform on sodium-phenol. 

Preparation. — Mix 10 parts of phenol with 20 parts of 
sodium hydroxide dissolved in 30 parts of water in a flask 
having an upright condenser, and gradually add 20 parts of 
chloroform. After heating the flask on a water-bath, until all 
chloroform has disappeared, add excess of hydrochloric acid, 
when a red-violet oil will rise to the surface. Pour the con- 
tents of the flask into a retort, and pass steam through it till 
no more aldehyde comes over. The reaction is as follows : — 

CeHjOXa + 3NaOH + CHCI3 = CeH.OXa.COH + 3XaCl + 2H2O 
Sodium- chloroform Sodium salicyl- 

phenol aldehyde ' 

Sodium salicylaldehyde, treated with hydi'ochloric acid and dis- 
tilled, gives salicylaldehyde : — 

CeH.OXa.COH + HCl = C,HXaH)COH + NaCl 

Sodium salicyl- Salicylaldehyde 

aldehyde 

The oil which passes over (orthohydroxybenzaldehyde) may be 
purified from phenol (with which it is always contaminated) by 
treating with acid sodium sulphite, which forms a compound with 
the aldehyde, leaving the phenol which may be removed by dis- 
solving it in ether. An isomeric salicylaldehyde (parahydroxy- 
benzaldehyde) is formed along with the ortho-aldehyde, and 
remains dissolved in the water in the retort, fi-om which it is pre- 
cipitated on cooling. 

Methyl Salicylate, CH.^C.H.O^, formerly known as ' ' gaultheric 
acid," forms the chief part, at least 90 percent,, of the essential 
oil of gaultheria {Oleum Gaultherice, U. S. P.) or winter-green, 
{Gaultheria procumbens, the fresh leaves of which yield about 0.4 
percent, of oil). It also occurs in several species of violet (Man- 
delin). Oil of sweet birch {Betula lenta) is methyl salicylate. 
Gaultherin, a glucoside existing in the bark of Betula lenta, when 
decomposed by mineral acids, by alkalies, or by heating the 
aqueous solution to 130°-140° C, yields a carbohydrate and methyl 
salicylate. Methyl Salicyla^, U. S. P. , is produced synthetically. 



TRIHYDROXYBENZOIC SERIES. 459 

Phemjl Salicylate, CgH.OH.CO.OCgH., {Phenylis Salicijlas, 
U. S. P.), or salol is an antiseptic, antipyretic, anti-rheumatic 
remedy. It is white, crystalline, soluble in alcohol, almost in- 
soluble in water, and has a faint aromatic odor. 

Othoform, a new anaesthetic, is the methyl ester of para-amido- 
meta-hydroxybenzoic acid. 

Vanillin or Methylprotocatechuic Aldehyde, {Vanil- 
linum, U. S. P.), CgHgO;, or CgH,X0H)(0CH3)CH0, is the sub- 
stance to which the odor and flavor of- vanilla are due. It also 
occurs in Siam benzoin, Rosa canina, etc. The white crystals 
commonly found on vanilla ( Vanilla, U. S. P.), (the prepared un- 
ripe pods of Vanilla planifolla), termed variillin, were found by 
Carles to be a weak acid. It occurs in vanilla to the extent of 
from 1^ to 3 percent. Vanillin has in recent years been prepared 
artificially by Tiemann and Haarmann from coniferin, a glucoside 
existing in the sap wood of pines. The substance remaining after 
the removal of glucose from coniferin, or, indeed, coniferin itself, 
by action of a mixture of potassium dichromate and sulphuric acid, 
yields vanillin. It may also be obtained by a series of reactions 
starting from that of carbonic anhydride on potassium-phenol ; 
also from the eugenol of oil of cloves. By action of hydrochloric 
acid, vanillin yields methyl chloride and protocatechuic alde- 
hyde. Artificial vanillin is now manufactured by various patented 
methods. 



The Trihydroxybenzoic Series. 

Acid of the Series, C,R,,_^,{OJI)fiOOB:. Gallic Acid, or tri- 
hydroxybenzoic acid, CeH2(OH)3C60H (see p. 343). By the 
elimination of one molecule of water from two molecules of gallic 
acid, tannic acid is produced. 



rcooH 

CeHj(OH), 

(CO ^ 

^ (0H)3 
Gallic acid Tannic acid 



^«-^2 1 (0H)3 



'"6^2 I (0H)3 J 



Gallic acid, by the action of heat yields pyrogallol ov pyrogalUc 
acid and carbonic anhydride. 

C,H,(0H)3C00H = C,H3(OH)3 + CO, 



460 ORGANIC CHEMISTRY. 

The Cinnamic Series. 

Acids of the Cinnamic Series, C„H2n_^C00H. — Cinnamic acid, 
CgH^COOH, may be obtained from the balsams of tolu and Peru, 
and from storax. It may be made artificially by aid of Perkin's 
reaction, which consists in heating 2 parts of benzaldehyde with 
3 of acetic anhydride and one of sodium acetate. 

1. Balsam of Peru {Balsamum Peruvianum, U. S. P.), an exu- 
dation from the trunk of Myroxylon Pereirce, is a rqixture of oily 
matter with about one-quarter or one-third of resinous matter and 
6 percent, of cinnamic acid. The oil, by fractional distillation in an 
atmosphere of carbonic anhydride, under diminished pressure, inx- 
nishes benzyl alcohol, CgH.CHgOH, benzyl benzoate, CgHgCO.OCjH^, 
and benzyl cinnamate, CgH^CO.OC^H^, or cinnamein (Kraut). By 
action of alcoholic solution of potassium hydroxide it yields 
potassium benzoate and cinnamate, and benzyl alcohol ; also cm- 
namyl alcohol, CgH.CH,,OH, otherwise known as peruvine or 
styrone. It also often holds in solution metacinnamein or styracin, 
CjgH^g02, polymeric with cinnamaldehyde, CgH.COH. The resin 
of balsam of Peru seems to result from the action of moisture on 
the oil. Any admixture of resin, oil, storax, benzoin, or copaiba, 
with balsam of Peru is detected by mixing 6 grains of slaked lime 
with 10 drops of the balsam, when a soft product results if the 
specimen be pure, but hard, if impure ; further, the mixture, on 
being warmed until volatile matter is expelled and charring com- 
mences, gives no fatty odor. 2. Balsam of Tolu {Balsamum 
Tolutanum U. S. P.), is an exudation from the trunk of Myroxylon 
Toluifera ; in composition it closely resembles balsam of Peru, but 
is more easily resinified. It contains benzyl benzoate and cinna- 
mate, cinnamic acid, a small proportion of benzoic acid (Busse), 
and about 1 percent, of a volatile hydrocarbon, tolene, Cj^H^g. 
The cinnamic acid crystals may be seen with a lens when a little 
of the balsam is pressed between two warmed pieces of glass. Old 
hard balsam of tolu is a convenient source of cinnamic acid, 
which may be extracted by the same process as that by which 
benzoic acid is obtained from benzoin — namely, ebullition with 
alkali, filtration, and precipitation by addition of hydrochloric 
acid. In syrup of tolu, {Syrupus Tolutanus, U. S. P.), the cinnamic 
acid is liable, if certain micro-organisms are present, to develop 
carbonic anhydride and acetylene, the latter communicating an 
unpleasant smell, CgHgOg = CO, + 4C2H2. 3. Storax is an oleo- 
resin obtained from Liquidambar orientalis. It contains a volatile 
oil termed styrol, cinnamene, or cinnamol, CgHg, — which possibly 
(Berthelot) is condensed acetylene, 4C2H2, — cinnamic acid, st^^ra- 
cin, or cinnamyl cinnamate, CgH.CO.OCgHj,, and a soft and a 
hard resin. Styrol differs from similar hydrocarbons in being 
converted into a polymeric solid, termed metastyrol or draconyl, 
on heating to about 400° F. (204.4° C). For medicinal use, 



DIBASIC ACIDS. 461 

storax {Styrax, U. S. P.), is purified by solution in alcohol, filtra- 
tion, and removal of the alcohol by distillation. By oxidation 
with potassium dichromate and sulphuric acid it yields an odor 
resembling that of essential oil of bitter almonds. 

Coumariu, CgHgOg (the principle of the Tonka bean), may be 
obtained by acting on the sodium-derivative of salicylaldehyde 
with acetic anhydride and sodium acetate (Perkin). 



Dibasic Acids. 
These have two carboxyl (COOH) groups in the molecule. 
The Succinic Series. 

Acids of the Succinic Series, CnH2„(COOH)2. — These acids may be 
formed by the oxidation of glycols, or by the action of water 
and hydrochloric acid on the cyanides of the olefines, obtained by 
acting on the olefine dibrom-addition products with potassium 
cyanide. 

Oxalic Acid, H.jOfi^ or (C00H)2, is the first of this series. It 
may be obtained by oxidizing glycol, C2H4(OH)2 — 

CH2OH COOH 

I + 2O2 = I + 2H2O 

CH2OH COOH 

Glycol Oxalic acid 

Also by the action of carbonic anhydride on sodium : — 
2CO2 + 2Na = Na2C20, 

Carbonic anhydride Sodium Sodium oxalate 

For other methods, see Oxalic Acid, p. 302. 

Oxamide, C202(NH2)2, the analogue of urea — carbamide, 
CO(NH2)2 — is formed on mixing ethyl oxalate w^ith ammonia 
water; or by passing cyanogen into aqueous hydrochloric acid, 
C2N2 + 2H2O = (CONH2)2. 

Succinic Acid, C2H(,COOH)2. {See p. 339). 

The Malic Series. 

Acids of the Malic Series, C„H2n_iOH(COOH)2.— Malic, or 
hydroxysuccinic acid, C2H3(OH) (COOH).^, is obtained artificially 
by acting on bromosuccinic acid, C2H3Br(COOH)2, wath moist 
silver oxide, the bromine being replaced by hydroxyl. It is con- 
tained in unripe mountain-ash berries, morello cherries, etc. {See 
p. 332.) 

Asparagin (amidosuccinamic acid), CgHgNH^x p.^xr/^ 
{See p. 332). ' ' 



462 ORGANIC CHEMISTRY. 



The Tartaric Series, 

Acids of the Tartaric Series, CJ1^,_,{0B.).XC00II\. —Tartaric 
Acid, (dihydroxysuccinic acid), C2H2(OH)2(COOH)2, may be ob- 
tained by oxidizing erythrite, C2H2(OH)2(CH20H)2. [See p. 
444). For other modes of formation, see p. 305. There are four 
isomeric tartaric acids, differing in their relation to polarized 
light. 

The Phthalic Series. 

Acids of the Phthalic Series, 0Jl2r^_^{C001A)^.— Phthalic Acid, 
CgH^(C00H)2, is obtained by the oxidation of naphthalene and 
naphthalene tetrachloride, or a mixture of benzene and benzoic 
acid. By distillation it forms phthalic anhydride, CgH^O^, and 
this, when heated Avith phenol and sulphuric acid, yields pjienol- 
phthalein, a light yellow crystalline powder, which, when dissolved 
in alcohol, is used in alkalimetry on account of its property of turn- 
ing reddish-purple in presence of the slightest excess of alkali. 
There are three phthalic acids, ordinary phthalic or orthophthalic 
acid, isophthalic or metaphthalic acid, and terephthalic or para- 
phthalic acid. {See p. 411.) 

Teibasic Acids. 

These have three carboxyl (COOH) groups in the molecule. 
Tricarballylic Add, or propane-tricarboxylic acid C3H5(COOH)3, is 
the first of these acids ; its hydroxy-derivative is citric acid, 
C3H^(OH)(COOH)3 (hydroxy-propane-tricarboxylic acid), found in 
a variety of fruits. It has already- been described {see p. 308). 

Other Polybasic Acids. 

Tetrabasic acids — as pyromellitic acid, CpH2(C00H)^ — and hexa- 
basic acids — as mellitic acid, Cg(COOH)g — are known. 

Ketones. 

Just as primary alcohols on losing hydrogen by oxidation yield 
aldehydes, so secondary alcohols {see p. 417) yield ketones : — 

aH2„^.iCH20H — H, = C„H2„+aC0H (aldehyde) 
(C„H2„+02CHOH — H; = {CJA,.^,\ CO (ketone) 

Like aldehydes, ketones are converted by reduction with hydro- 
gen into the corresponding alcohols. Like aldehydes, ketones 
form crystalline compounds with acid sulphites. While, however, 
aldehydes by oxidation yield corresponding acids, ketones yield 
acids whose molecules have a smaller number of carbon atoms than 
the original ketones. 



RELATION OF ACETIC AND DIBASIC ACIDS. 463 



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464 OBGAXIC CHEMISTRY. 

Acetone, CgH^O, or dimetlujl-l-etone, (CH3),C0 or CH3.CO.CH3, 
Acetonum U. S. P., the best known of the class, may be obtained 
by strongly heating calcium acetate, carbonate remaining ; 
{ClA.fOO)f^ = (CH3)2CO + CaC03. The calcium salts of other 
fatty acids split up in a similar manner (hence perhaps the name 
- — from /cfw, keb, I si)lit, and the original acetone), yielding other 
ketones, as propione, butyrone, valerone, etc. The mixed calcium 
salts give corresjDonding ketones. Thus acetate and caprate yield 
methyl-nonyl ketone, CH3 — CO — CgH^g, the chief natural constit- 
uent of oil of rue. Acetophenone or phemjl-methyl ketone, CgH., 
CO.CH3, is known as hypnone. 



QUESTIONS AXD EXEECISES. 

Give general methods for the formation of aldehydes and acids. — How 
is acetaldehvde prepared ? — Describe the reactions that occur in the manu- 
facture of chloral and hydrated chloral. — What is the nature of the action 
of alkalies on hydrated chloral ? — Mention the characters of pure and 
impure liydrated chloral. — What relation has valeric acid to amyl alcohol ? 
Give the relations between the acetic and lactic series of acids. — To what 
series do the following acids belong : — oleic, butj^ric, oxalic, and citric? — 
How is benzoic acid prepared? — Give the differences between balsam of 
Pern, tolu, and gum benzoin. — -How is oil of bitter almonds prepared, and 
how can it be distinguished from so-called artificial oil of bitter almonds ? 
— Give methods of preparing artificial salicylic aldehyde and acid. — Give 
systematic names of tartaric, succinic, carbonic, salicylic and citric acids. 



Volatile Oils. 



The Volatile or Essential Oils exist in various parts of plants. 
They usually are mixtures of the liquid hydrocarbons or elceoptens 
(from e/aiov, elaion, oil, and d~rouai, optomai, to see) with oxidized 
hydrocarbons, Avhich are commonly solid or camphor-like bodies 
termed stearoptem (from areap, stear, suet), and which on cooling 
often crystallizes out ; or on distilling an oil the stearopten may 
remain in the retort, being less volatile than the elfeopten. The 
volatile oils often are associated with further oxidized substances 
termed resins. 

The tendency of the results of recent investigations is to show 
that instead of the characteristic odor of an essential oil being due 
to one single principal constituent, the other bodies present have a 
distinct influence in determining the odor. Oils of caraway, anise, 
and linaloe are examples of those in which the aroma is due to a 
single odorous substance — carvone, anethol, and linalol ; but in 
many volatile oils the conditions are more complex. Kose oil affords 
a .striking example of the important influence which combinations 
of odoriferous bodies sometimes exercise on the perfume ; the oils 
of rose, geranium, and palmarosa contain approximately the samq 



KETONES. 465 

percentage of geraniol, which is identical in the three oils. While, 
however, geranium and palmarosa oils are valued in proportion to 
the amount of geraniol they. contain, the value of rose oil depends 
upon the various other substances present. 

The process by which volatile oils are usually obtained from 
herbs, flowers, fruits, or seeds, may be imitated on the small 
scale by placing the material (bruised cloves or caraways, for 
instance) in a tubulated retort, adapting the retort to a Liebig's 
condenser, and passing steam, from a flask, through a glass 
tube to the bottom of the warmed retort. The steam in its 
passage through the substance takes up some of the vapor of 
the oil and carries it into the condenser, whence, cooled and 
liquefied, it flows along with the condensed water, into the 
receiving vessel, where it will be found floating on the water. 
It may be collected by running off" the distillate through a 
glass funnel having a stopcock in the stem, or by letting the 
water from the condenser drop into a test-tube or similar tube 
which has a small hole in the bottom, and is placed in a larger 
vessel containing water, the water and oil being subsequently 
run off separately from the tube as from a pipette. The water 
will in most cases be the ordinary official medicated water of 
the material operated on {Aqua, Anisi, Aurantii Florum, 
Cinnamomi, Fceniculi, Menthce, Piperitce, Menthm Viridis, 
Rosce). Volatile oils, like fixed oils, stain paper ; but the stain 
of the former is not permanent like that of the latter. Oils of 
lemon and orange are sometimes obtained by mere pressure of 
the rind of the fruit. Volatile oils are " concentrated " by 
removing inodorous terpene, whereby the so-called terpeneless 
oils are obtained. 

The presence of alcohol in an essential oil may be detected and 
its quantity estimated by shaking with an equal bulk of pure 
glycerin. The»latter dissolves the alcohol, and is augmented in 
volume according to the amount of alcohol present (Bottger). 
(For tests for alcohol, see p. 423.) 

A large number of volatile oils are employed in medicine, either 
in the pure state, in the form of saturated aqueous solutions 
(medicated waters), or solutions in alcohol {Spiritus Amygdalae 
Amarce, Anisi, Cinnamomi, Gaidtherioe, Juniperi, Lavandnlce, 
Metiihce Piperitce, Mentha', Viridis, or as leading constituents in 
various barks, roots, leaves, etc. Perfumes ( ' ' scents " or ^ ' essences, ' ' 
including ''lavender-water" and ''eau de Cologne") are for the 
most part solutions of essential oils in alcohol (45 to 90 percent.), 
or spirituous infusions of materials containing essential oils. 
The following oils are, directly or indirectly, included in the 
30 



466 ORGANIC CHEMISTRY. 

Pharmacopaeias^ : — 1. VolatiJe oil of Bitter Almond {see p. 497), 
2. Oil of the fruits of Ajwain or Omum, Carum Ajowan, or 
Ptychotis Ajoican, contains cymol or cijmene (C^^H^J, and a 
stearopten {AJwainka-phid, flowers of ajwain) identical with. thj/7no I, 
CjqH^^O. 3, Oil of Dili, a pale, yellow, pungent liquid of 
sweetish Avarm flavor, distilled from dill-fruit; it contains a 
hydrocarbon, anethene (C^oH^g), and an oxidized oil (C^qH^^O) 
identical with the carvone of oil of caraway (Gladstone). 4. Oil 
of Anise [Oleum Anisi, U. S. P.), a colorless or pale yellow liquid, 
of sweetish warm flavor, distilled in Europe from the anise fruit 
[Pimpinella anisum), but chiefly in China, from the fruit of star- 
anise {Illicium verum); it is a mixture of a hydrocarbon, isomeric 
with oil of turpentine, and anethol, a stearopten (C^qH^jO) which 
crystallizes out at low temperatures. The melting point of anethol 
is 70° F. (21. 1° C.) (Moreau and Chauvet). Oil of Anise congeals, 
when stirred, at temperatures between 50° and 59° F. (10° to 
15° C), and should not again become liquid below 59° F. (15° C). 
The congealing point of the natural oils appears to be dependent 
on the proportion of the fluid to the solid constituent, a very small 
quantity of the former lowering the congealing and melting points 
very considerably. 5. Oil of Betida {Oleum Betulce, U. S. P.), 
obtained from the bark of the Sweet Birch, Betula Lenta. Com- 
pare methyl solicylate, p. 458. 6. Oil of Chamomile, a bluish or, 
when old, yellow oil, of characteristic odor and taste, distilled 
from chamomile-flowers [Anthemis U. S. P.). The official variety 
[Anthemls nobilis) yields about 0. 2 percent, of an oil composed of 
a hydrocarbon (Cjf,H,g) and an oxidized portion (C^oHj^Og) Avhich, 
heated with potash, gives potassium angelate (KC^H^O^), whence 
is obtained angelic acid (HC5H,02). According to Demarcay, 
Kopp, and Kobig, the oil is a mixture of butyl and amyl angel- 
ates and similar bodies. Naudin has also obtained from chamo- 
miles anthemen, a hydrocarbon crystallizing in needles. The 
flowers of another variety [Matricaria chamomilla) contain a 
stearopten (C^oHjgO) having the composition of laurel-camphor. 
7. Oil of Horse-radish root seems to consist mainly of ally iso- 
thiocyanate, C^H-NCS. 8. Oil of Orange peel f^Oleum Aurantii 
Corticis, U. S. P.), and the oils of various species of Citrus; namely: 
— 9. Lemon [Oleum Limonis, U. S. P., from Limonis Cortex, 
U. S. P., the fresh outer part of the pericarp of the fruit of (7. 
medica, var. ^ Limonum); 10. Lime (Italian, from C. limetta; 
West Indian, from C. medica, var. acidd); 11. Bergamot {irom C. 
bergamia)) 12. Citron and a variety of citron termed cedra ; 
resemble each other in com]:)Osition, all containing a variety of 
limonene {hesperidene), a hydrocarbon, C,,H2^, and a small 
quantity of oxidized hydrocarbons [CjoHjoOg, Ci^Hj^O, and 

1 The student is not expected to remember, but to understand, all that 
follows respecting the volatile oils. 



VOLATILE OILS. . 467 

(Wright and Piesse) CgQlTg^Oa], etc. Lemon oil consists chiefly 
of a limonene, CioH^g, boiling at 176° C, together with a small 
quantity of phellandrene. Its chief aromatic constituents are the 
aldehydes, citral, CjoHj^O, and citronellal, 0^0^18^- ^ terpene- 
less oil of lemon has been described by Geissler, who states that it 
excels the commercial oil in odor, flavor, and stability. Oil of 
bergamot appears to owe its fragrance to 40 or 50 percent, of Imalyl 
acetate, C^gHj^CgHgOg. It also contains a stearoj^ten, bergapten, 
CjgHgO^. Expressed lime essence contains a soft resin. 13. Oil 
of Neroli or Orange-Flower (distilled from the flowers of the bitter 
orange tree. Citrus Aurantium, var. Bigaradia), the aqueous solu- 
tion of which is ofiicial in the forms of water [Aqua Aurantli 
Florum, U. S. P. and Aqua Aurantii Florum Fortior, U. S. P.), 
and syruj) {Syrupus Aurantii Florum, U. S. P.), contains a fra- 
grant hydrocarbon (C^oH^g), colorless when fresh, but becoming 
red on exposure to light, and an inodorous, oxidized hydrocarbon. 
Strong acids, especially nitric, attack the oil in orange-flower water, 
imparting to the fluid a rose tint. 14. Oil oi Petit Grain, dis- 
tilled from the leaves and shoots of the orange-tree, consists chiefly 
oi linalyl acetate , Q-^^^^C^^O^. 15. The leaves of ^o/c?o (P(S^«?ms 
Boldus), a Chilian shrub (tonic and hepatic), yield 2 percent, of 
essential oil (and, according to Bourgon and Verne, an alkaloid, 
boldine). 16. Oil of Buchu-leaves {Buchu, U. S. P.), consists 
chiefly of a fluid oil, C^oHjgO, holding in solution a crystalline 
stearopten, diosphenol, CioH^gOg. 17. Oil of Cannabis indica, see 
p. 474. 18. Oil of (the lesser) Cardamoms, from the seeds of 
Elettaria repens (Cardamonmm, U. S. P.), freed from their peri- 
carps, is chiefly a hydrocarbon (CjoHj^) isomeric with oil of tur- 
pentine (terpilene and probably limonene) and a camphor resem- 
bling turpentine-camphor (C,oH,p, 3H2O). 19. Oil of Cajuput 
{Oleum Cajuputi, U. S. P.), from the leaves oi Melalhica Leucaden- 
dron, is a mobile bluish liquid, consisting of hydrous cajuputene, 
cajuputol, or cineol {eucalyptol), C^oHi^OH, and terpineol as well as 
butyric, valeric, and benzoic aldehydes. Fresh cajuput-oil has a 
green hue, which is perhaps transient, for the color of the commer- 
cial oil is due to copper (Guibourt and Histed): certainly the green 
coloring-matter of pure cajuput-oil is organic and either oily or 
chlorophylloid. 20. Oil of Caraway-frwit {Oleum Carl, T\.^.V., 
from Carum, U. S. P.), is a mixture of carvone (formerly called 
carvol) (CjoH^^O) and cervene which is a limonene (C^pH,^). 21. Oil 
of Gloves [Oleum Caryophylli, U. S. P.), and of Pimento {Oleum. 
Pimentce, U. S. P.), both heavier than water, consist of eugenol 
[Eugenol, U. S. P.), (CjoH,202) and a sesquiterpene, O,.!!.^^ {caryo- 
phyllene in the case of oil of cloves, which contains also traces of 
vanillin). 22. Oil of Cascarilla has not been fully examined. 
23. Oil of Cinnamon and of Cassia is mostly cinnamic aldehyde 
(C^H^COH), Cinnalaetydum, IJ. S. P. It also contains eugenol 
and phellandrene. Boiled with nitric acid, it yields benzaldehyde, 



468 ORGANIC CHEMISTRY. 

CgH^COH, and benzoic acid, C^H^COOH; with chlorinated lime 
it yields calcium benzoate, (CgH.C00)2Ca ; and with potassium 
hydroxide it gives potassium cinnamate, CfiH^COOK. The sp. gr. 
of oil of cinnamon {Oleum Cinnamomi, U. S. P. ), varies from 1.045 
to 1.055. 24. Oil of Cifronella, a Grass Oil, from Andropogon 
nardus, is chiefly composed of citronellal, CjoHjgO. Kremers also 
obtains hep toic aldehyde, C.Hj^O, a terpene (CjoHjg), etc. 25. Oil 
of Copaiba {Oleum Cojmibce, U. S. P.), and, 26, of Cubeb {Oleum 
Cubebce, U. S. P.), contain sesquiterpenes, Q^^^^. The cubebene 
of the latter oil is sometimes associated with hydrous cubebene, the 
so-called cubeb ccanphor, Cj^H^.OH. Oil of cubeb also contains a 
small quantity of a terpene (CioH^g). 27. Oil of Coriander { Oleum 
Coriandri, U. S. P.), consists of coriandol, C^oH^gO, and a terpene, 
CjoH^g. 28. The fruits of Cumin or Cummin [Cuminum Cyminum), 
an ingredient of many curry -powders, contain about 3 percent. , and 
those of Water Hemlock or Cowbane ( Cicuta virosa) about 1^ percent., 
of an essential oil comj^osed of cymol or cymene. Cj^Hj^, and cuminic 
aldehyde, CyHj^COH. The latter is an aldehyde which readily unites 
with alkali-metal bisulj^hites and yields byoxidation cuminic acid, 
CgH^^COOH. Cymol also occurs in Garden Thyme ( Thymus vul- 
garis). 2<^. 0\\ of Erigeron, [Oleum Erigerontis,\].^. v.). 30. The 
fresh leaves of Eucalyptus globulus, E. oleosa, E. conerifolia, E. 
dumosa, E. odorata, and other "mallee," ''scrub," or shrub-like 
eucalypts, furnish about 1 percent, of an oil {Oleum Eucalypti, 
U.S. P.), w^hich contains from 40 to 60 percent, of cienol or 
eucalyptol, C^qR^^O {Eucalyptol, U. S. P.), boiling at about 176° C, 
freezing at 0° C, sp. gr. 0.925 together with pinene, C^oHjg. E. 
amygdalina yields an oil which contains little cineol and muchphel- 
landrene (the latter more readily alterable than other terpenes, and 
characterized by yielding a crystalline mass with nitrous anhydride). 
E. maculaia, var. citriodora, contains an aldehyde similar to that of 
citronella. Difierent species of eucalyptus may yield oils differing 
in specific gravity, flavor, and odor. It is now generally accepted 
that the medicinal efficacy of eucalyptus oil is due to the cineol 
Avhich it contains. Like the turpentines the eucalyptus oils are 
good solvents of resins. Their sp. gr. A'aries greatly — from 0.030 
to 0. 040 below or above 0. 900. A^oiry states that cineol is present 
also in the oil of Lavandtila spica, oil of sjnke ov ''foreign" oil of 
lavender. Red gum is from the bark of E. rosfrata and other spe- 
cies, and is used solely for its astringent properties. 31. Ele- 
campane-root { Inula Heleninm) by distillation with water yields 
solid volatile helenin (CgH^O), inulol, a camphor-oil (CjoHj^O), 
and imilic anhydride or lactone {C^AA^^fd^, as well as, according to 
Marpmann, crystals of almdic acid {Q.^AA^p.^ and fluid alantol 
(CpH^jO) each more powerfully antiseptic than helenin. 32, Oil 
of' Fennel {Oleum Fcenicidli, U. S. P.), obtained from the fruit of 
Fwniculum, U. S. P.), differs in odor, but contains the same proxi- 
mate constituents as oil of anise. 33. Oil of Geranium, or Ginger 



VOLATILE OILS. 469 

Grass oil, from Andropogon schcenanthus, and various species of 
Pelargonium, contains geraniol (C^^H^gO). Barbier and Bouveault, 
however, give the name limonool to the essential oil of Androj^ogon 
schcenanthus, and state that it is different from oil of pelargonium. 
34. Grains of Paradise {Amomum melegueta), Guinea Grains or 
Melegueta Pepper, Semina Cardamomi Majoris, contain essential 
oil (CioHjg and CioH^gO) and a highly pungent principle, termed 
by Thresh paradol, Gfi^p^, isomeric with the capsaicin of the 
same chemist. 35. Oil of Hedeoma {Hedeoma, U. S. P., the leaves 
and tops of Hedeoma pulegioides) ov American Pennyroyal [Oleum 
Hedeoma U. S. P.), Qontama pulegone iO^^^fi), and yields ^soAe/)- 
toic acid (C^Hi^.,), and other substances (Kremers). 36. Oil of 
Juniper [Oleum juniperi, U. S. P.), contains pinene, C^oH^g, cadi- 
nene, CjgH^^, and a crystalline substance which has been called 
juniper camphor. 37. Oil of Lavender Flowers [ Oleum Lavandulce 
Florum, U. S. P.), contains linalool, linalyl acetate, and a minute 
proportion of cineol ; pinene, CioH^^, is present in some samples, 
but is not a constant constituent. 38. Oil of Myrcia, oil of bay, 
or bayberry oil (sp. gr. 0.975 to 0.990) is obtained from the leaves 
of Myrcia acris. It contains eugenol with some methyl- eugenol 
and small quantities of other substances. 39. Oil or butter or 
camphor of Orris [Iris Florentind) is a soft solid lighter than water. 
Fliickiger and Hanbury found it to be chiefly myristic acid asso- 
ciated with a small quantity of essential oil. 40. Oil of Pepper- 
mint {Oleum MenthcB PiperitcE U. S. P.) contains several hydrocar- 
bons, CjgHjg, menthone, CjoH^gO, and other bodies, and deposits 
crystalline peppermint camphor known as menthol, CjoHigOH, 
when exposed to 'low temperatures. The latter is official {Menthol, 
U. S. P.). It is also yielded by the oil of Mentha arvensis (vars. 
piperascens and glabra). 41. Pulsatilla : — Various species of 
Anemone and Ranunculus yield an acrid oil which with water gives 
poisonous crystalline a/? emo/ii/i [O^.lA^fi^) and amorphous anemomc 
acid (Cj.Hj^O^). 42. Oil of Spearmint {Oleum Menthm Viridis, 
U.S. P. ), the common Mint of the kitchen garden, contains carvone, 
C^oR^fi, and a terpene. 43. Oil of Pennyroyal {Mentha Pulegium) 
consists chiefly of the ketone, pulegone (CjoH^gO). 44. Oil of 
Nutmeg {Oleum My risticce, U. S. P.), is composed of a hydrocarbon, 
myristicene (CjoHjg), and myristicol (CjoH^gO), and cymene 
(C^oHi^) (Gladstone). Mace, the arillus or net-like envelope of 
the nutmeg appears to yield similar bodies and also myrisficin, 
^12^14^3 (Semmler). 45. Oil or Otto or Attar of Roses (Oleum 
Rosce, U. S. P.), contains citronellol (CioH,,,OH), geraniol (C,oH^. 
OH), and minute quantities of other constituents ; the odor is not 
due to any single substance, but to the blending of geraniol and the 
other constituents. According to Fliickiger, the solid hydrocar- 
bon also present yields succinic acid as the chief product of its 
oxidation by nitric acid, and in other respects affords evidence of 
belonging to the paraffin series of fats. A(pia Rosa', U. S. P., is 



470 ORGANIC CHEMISTRY. 

obtained by diluting with water the official Aqua Eosse Fortior. 
The latter is ''water saturated with the volatile oil of rose petals, 
obtained by distillation." 46. Oil of Rosemary-tops {Oleum Ros- 
mariiii, U. S. P.), exists in the plant to the extent of from 1| to 3 
parts per 1000. It contains a hydrocarbon (CjoH^g) resembling 
that from Myrtle, Myrtus commu7iis, also camphor (CjoH^gO) and 
borneol and cineol (Cj^H^yO) in variable proportions. 47. Oil of 
Rue contains methyl-nonyl-ketone, Cj^H220 or CH3 — CO — CgH^g 
as chief constituent. Gorup-Besanez and Grimm have obtained 
artificial oil of rue {Q^^^^O), as one of the products of the destruc- 
tive distillation of calcium acetate and caprate {see Ketones). 
According to Greville Williams oil of rue is chiefly euodic alde- 
hyde {O^^.^^O), some lauric aldehyde (Cj2H2^0) also being present. 
48. Oil of Sage contains the hydrocarbon pinene, CjoH^g, along 
with thujone, CioHj^O, and cineol and borneol, Cj^H^gO. 49. Oil 
of Savin {Oleum Sabince, U. S. P.), obtained from the topsof Jwwi- 
perus Sabina, contains sabinol, CjpHjgO, and sabinyl acetate. 
According to Wallach, it contains also a sesquiterpene, CuH,^. 
50. Oil of Elder-flowers occurs in the flowers in very small quan- 
tity ; it has a butteiy consistence ; it contains a terpene (CjoHjg), 
and probably a paraffin. 51. Oil of Sandal-wood {Oleum jSantali, 
U. S. P. ) is composed (Chapoteaut) of two substances : mostly of 
sanfalal, an aldehyde having the formula Ci5H2^0 (boiling at 572° 
F.,300°C.), and a small quantity of the corresponding alcohol hav- 
ing the formula C15H26O (boiling at 590° F., 310° C). It occurs to 
the extent of about 2J percent, in the fragrant white or yellow 
sandal-wood of India, Santalum album, a small tree of the natural 
order Santalacese, and not to be confounded with the Pterocarpus 
santalinus, a tree of the natural order Leguminosae, which furnishes 
the inodorous Red Sandal-wood or Red Saunders Wood or Bar- 
wood of the dyer. 52. Oil of Sassafras {Oleum Sassafras. U.S. P.), 
contains nine-tenths of its weight of Safrol or Sassafrol, CjoHjq02, 
(Safrolum U. S. P.), also eugenol and a small quantity of a ter- 
pene. Sassafras camphor, C^oHigO, is deposited when the oil is 
exposed to a low temperature. 53. Oil of Black Sassafras, so- 
called, from the dried bark of Cinnamomum olivej^i also contains 
safrol and eugenol as well as cineol and cinnamic aldehyde. 54. 
Oil of Mustard {Oleum Sinapis Volatile, U. S. P.), consists of all yl 
iso-thiocyanate, C^H^NCS, with small quantities of allyl cyanide, 
C.jHgCN {see p. 427). If contaminated with alcohol, its sp. gr. 
is below 1.015. 55. Oil of Sweet Flag {Acorus calamus) contains 
a terpene, CioHi^. (The rhizome is said to contain Acorin, C^gHg^jOg 
a bitter glucoside). 56. Oil of common garden Thyme ( Oleum 
Thymi, U. S. P.), contains cymene or cymol (CjoH^J, thymene 
Cj„II,g), and thymol and carvacrol {C^Qii^Jd). Thymol, U. S. P., 
may be obtained from oil of Thymus vulgaris, Monarda punctata, 
or Carum copticum. Thymol crystallizes out when oil of thyrne 
or of ptychotis, etc., is kept at a low temperature for a day or two. 



VOLATILE OILS. 4T1 

It may also be obtained by shaking the oils with caustic alkali, 
and treating the separated alkaline liquid with an acid. It may 
be purified by distillation, or by crystallization from alcohol. It 
would seem that as an antiseptic thymol is quite as valuable as 
carbolic acid. Thymol Iodide (Thy7nolis lodidum) is official. 57. 
Oil of Turmeric {Curcuma longa) is said by Jackson and Menke to 
be chiefly an alcohol having the formula CjgHg^OH. They name 
it turraerol. It is a light yellow volatile oil, having the sp. gr. 
0. 902. It is to this oil that turmeric (hence curry powder, partly) 
owes its flavor and odor. 58. Oil of Valerian-root ( Valerianae, 
U. S. P. , from Valeriana officinalis) contains the two terpenes, cam- 
phene and pinene, CjoHig, together with several borneol esters — 
formic, acetic, butyric, and, especially, iso-valeric. A sesquiter- 
pene, Ci5ll24, and some other substances are also present. Accord- 
ing to Bruylants, the strongly-smelling iso-valeric acid does not 
exist free in the oil, but is formed by the decomposition of the 
borneol ester. Iso-valeric acid can rapidly be obtained from the 
rhizome by oxidation with a mixture of potassium dichromate 
and dilute sulphuric acid. The potassium salt is formed in quan- 
tity when oil of valerian is allowed to fall, drop by drop, on heated 
potassium hydroxide, and by the action of sulphuric acid on the 
potassium salt thus produced, iso-valeric acid is obtained. Valeri- 
ana Wallichil furnishes an Indian valerian oil resembling, in its 
general characters, the oil from V. officinalis. 59. Indian oil of 
Verbena, Lemon-grass Oil, or Indian Melissa Oil, is obtained from 
Andropogon citratus. It consists mainly of citral associated with 
small quantities of an isomeric aldehyde and of citronellal. 60. 
Oil of Ginger {Zingiber, U. S. P.), is, according to Thresh, a com- 
plex mixture of hydrocarbons and their oxidation products ; cym- 
ene (CjoHi^) is present, a terpene, aldehydes, and ethereal salts. 
61. The oil obtained from the so-called tvorm-seed {Artemisia 
marifima) consists mainly of cineol (CipHjgO), American Worm- 
seed contains a volatile oil {Oleum Chenopodii, U. S. P.). 

Caoutchouc or India-rubber, and Gutta Percha. 
Caoutchouc is the hardened juice of Dichopsis Gutta, Hevea 
(several species), Castilloa elastica, Urceola elastica, Ficus elastica, 
and other plants. Heated moderately with sulphur, it takes up 
2 or 3 percent, and forms vulcanized India-rubber; at a higher tem- 
perature a hard horny product, termed eboniie or vulcanite, results. 
The official India rubber [Elastica, U. S. P.), is '' the prepared 
milk-juice of several species of Hevea." Gutta Percha is the 
concrete "drop" or juice of the percha (Malay) tree, Isonandra 
gutta, and of other Sapotaceous plants. White gutta percha is 
obtained by precipitating a solution of the ordinary gutta percha 
in chloroform by the addition of alcohol, washing the precipitate 
with alcohol, and finally boiling it in water and moulding it into 
the desired form while still hot^ 



472 ORGANIC CHEMISTRY. 

These two elastic substances, in the pure state, are hydro- 
carbons (OgH^)^, usually slightly oxidized. AVhen caoutchouc is 
distilled, a terpene, CioHje) called caoutchin, is obtained. 



Camphors. 

In addition to the stearoptens or camphors already mentioned as 
being contained in or formed from volatile oils, there is one that 
is a common article of trade. It is obtained from the wood of 
Cinnamomum Camphora, or Camphor-laurel, in Japan (termed in 
Europe, Dutch camphor, because imported by the Dutch) and in 
China (known as Formosa camphor), by a rough process of distil- 
lation with water, and is resublimed in this country ( Camphora, 
U. S. P.). The formula of laurel-camphor is C.oH^gO. Sp. gr. 
about 0.990; melting point, 175^ C; boiling point, 204° C. 
Bromine heated with camphor gives monobromated camphor 
C^oHjgBrO) and hydrobromic acid. Eecrystallized monobromated- 
camphor occurs in white prisms ( Cam^wm J/o/io6;-o;wa^a, U. S. P.). 
The essential oil, from which doubtless camphor is derived by 
oxidation, is easily obtained from the wood, and is occasionally 
met with in commerce under the name of liquid camphor or camphor- 
oil. It contains hydrocarbons resembling terebenthene and citrene, 
and hydrous camphor (CjoH^gO,H.,0) as well as camphor. By 
exposure to air it becomes oxidized and deposits common camphor. 
Camphor distilled with phosphoric anhydride yields cymene, 
CjoHj^. There is another kind of camphor, Borneol, in European 
markets, less common than laurel-camphor, but highly esteemed 
by the Chinese; it is obtained from Dryobalanops aromafica, and 
is denominated Sumatra or Borneo Camphor. It differs slightly 
from laurel-camphor in containing more hydrogen, its formula 
being Cj^H^gO. It may be obtained by acting on camphor with 
hydrogen, the camphor being dissolved in some inert liquid such 
as toluene, and sodium added; the sodium forms a compound, 
^10-^15^-^^' ^'liile the hydrogen thus liberated acts on another 
portion of the camphor, forming borneol, CiqH^.OH— a better result 
being obtained if absolute alcohol is used' instead of toluene 
(Jackson and Menke). Borneo camphor is accompanied in the 
tree by a volatile oil fC.^H,/) isomeric with oil of turpentine. 
Inis oil, oorneene, is also occasionally met with in trade under the 
name of liquid camphor or camphor-oil, but differs from laurel- 
camphor oil in not depositing crystals on exposure to air. 

The constitution of the camphors is still somewhat doubtful. 
Camphor is soluble to a slight extent in water, about 1 in 700. 
The official Camphor Water (Aqua Camphorre, U. S. P.), is a 
solution obtained by dissolving cam]ihor in a little less than its 
own weight of alcohol, triturating the solution with purified talc, 



BESINS. 473 

permitting most of the alcohol to evaporate, then gradually adding 
water to the residue, and filtering till clear. 

Common camphor, and many other of the camphors, oily 
hydrocarbons, and oxidized hydrocarbons, yield camphoric acid, 
CgHj^(C00H)2, {Acidium Camphoricum, U. S. P.), and camphor- 
onic acid, C^H9(OH)(COOH)2, when attacked by oxidizing agents. 
Such reactions indicate natural relationships. Camphoric acid is 
an antiseptic. Ceratu7n Camphorce, Liimnentum Camphorcd, and 
Spiritus Camphoroi are official. 

Cantharidin, C^qH^^^^j ^^^ active blistering principle of can- 
tharides {Cantharis, U. S. P.) and other vesicating insects (such 
as Mylabris cichorii or Telini Fly, Mylabris phalerata, and others 
common in India), has most of the properties of a camphor or a 
stearopten. It slowly crystallizes from an alcoholic tincture of the 
beetles, in fusible, volatile, micaceous plates. The following pro- 
cess for the extraction of cantharidin is by Fumouze: Powdered 
cantharides are macerated with chloroform for twenty-four hours; 
and this treatment is repeated twice with fresh quantities of 
solvent, the residue having been well squeezed each time. The 
collected solutions are then distilled, and the dark-green residue 
treated with carbon bisulphide, which dissolves fatty, resinous, 
and other matters and precipitates the cantharidin. The precipi- 
tate is placed on a filter, washed with carbon bisulphide, and 
recrystallized from chloroform. Greenish and Wilson published a 
process for the quantitative determination of cantharidin in can- 
tharides. (See Pharmaceutical Journal, vol. Ix., p. 255.) The 
average amount found is six or seven parts in one thousand. Can- 
tharidin is readily soluble in warm glacial acetic acid, and 
still more readily in acetic ether or chloroform. Cantharides from 
which the fat has been removed by petroleum ether yield their 
cantharidin with great facility. 

Massing and DragendorfF consider cantharidin to be an anhy- 
dride, and that with the elements of water it {orms cant haridic acid 
(H^Cj^Hj^O-). Piccard gives to cantharidin the formula CjoHjgO^. 
Homolka assigns to it the formula CgH^^O.^CO. COOH. 

Ceratum Cantharides, and Tinctura Cantharidis are official. 

Resins, Oleoresins, Gum-Resins. 

Resins seem to be products of the oxidation of terpenes and 
the allied hydrocarbons; they occur in plants, generally in associa- 
tion with volatile oils. They closely resemble camphors and 
stearoptens, but are not volatile, and differ from oils and fafs 
chiefly in being solid and brittle. For convenience they are 
classified as resins, oleoresins, and gum-resins, the distinctions 
being founded as much on physical as on chemical properties. 

Oleoresins are mixtures of a resin and a volatile oil. 

Gum-resins are mixtures of a resin or oleoresin and srum. 



474 ORGANIC CHEMISTRY. 

Balsams are commonly described as resins or oleoresins which 
yield benzoic and cinnamic acids; they are Benzoin {Benzo'uium, 
U. S. P.), Balsam of Peru {Balmmum Peruvianum, U. S. P.), 
Balsam of Tolu {Balsamum Tolutanum. U. S. P.), and Storax 
{Styrax, U. S. P.), and are respectively treated of under the 
above-named acids. 

Some oleoresins, containing neither of the above acids, are often 
termed balsams {e.g., balsam of copaiba, and Canada balsam); 
these are described under the head of Oleoresins. 

PESi:Nrs^. — Resin, rosin, or colophony {Resina, U. S. P.), is the 
type of this class. Its source is the oleoresin or true turpentine 
of the conifers, a substance which by distillation yields spirit of 
turpentine and a residuum of rosin. ' 'Brown' ' and ' 'white' ' resin 
are met with in trade. The former is the residue of American, 
the latter of Bordeaux turpentine (from Pinus Abies, etc., and 
Pinus maritima respectively). The chief constituents of brown 
resin are pinic acid, HCg^H^gO,, and sylvic acid, identical in com- 
position but differing in prop'erties {see Isomerism), the former 
being soluble and the latter insoluble in cold alcohol. White 
resin or "galipot" is chie-^j pimaric acid, also isomeric with 
pinic acid. Pinic acid, cautiously heated, yields colophonic or 
colopholic acid. Eesin, by destructive distillation, yields resin oil, 
the first portion being "pale," the next "blue," and the third 
"green" resin oil. Mixed with other oils, these oils are used for 
lubricating purposes and in the manufacture of printing ink. 
Among the products of the destructive distillation of resin, Tich- 
borne found ''colophonic hydrate,'' C^^^Jd.^, HgO, a white 
inodorous crystalline substance, and by depriving this of water 
obtained white crystalline colophonin, C,oH220.^. Eesin is soluble 
in oil of turpentine. Contact with sulphuric acid immediately 
colors it strongly red. 2. Arnicin C20H30O,, the chief acrid, and 
one of the active, principles of the rootlets and rhizome of Arnica 
and of the flowers {Arnica, U. S. P.), is a resin, and, probably, a 
glucoside. 3. Cannahin, said to be the active principle of Indian 
Hemp {Cannabis Indica, U. S. P.), was obtained in 1846 by T. 
and H. Smith, and is a resin. According to Yignolo the essential 
oil of Cannabis Indica, purified by distillation in a current of 
steam and extraction with ether, is a mobile liquid boiling at 
248°-268°C. After repeated distillation from metallic sodium in 
order to remove a stearopten, it yields a sesquiterpene, 0,-112^, as 
a mobile colorless oil of aromatic odor which boils at 256°, and 
has a density of 0.897 at 15.3° C, and is slightly Ltvo- rotatory. 
This soon resinifies on exposure to air, and on adding concen- 
trated sulphuric acid to its chloroform solution the liquid becomes 
first green, then blue, and red on heating. Yignolo concludes 

' The student is not expected to reniemher, but to understand all that 
follows respecting the resins. 



RESINS. 475 

that the ''cannabene" prepared from this oil by Personne, was a 
mixture. Preobraschensky has stated, and since re-asserted, that 
the active principle is nicotine. Kennedy searched for nicotine 
by two methods, but found none. Hay found an alkaloid, tetano- 
cannabine; Siebold and Bradbury, also H. F. Smith, an alkaloid 
termed caunabinine. Warden and Waddell, after careful investi- 
gations, consider that the active principle of the plant has yet to 
be isolated. Jahns finds choline present. The native names of 
Indian hemp, that is, of the cultivated ''dried flowering or fruit- 
ing tops of the female plants of Cannabis sativa," are ganga and 
gunjah. It is chiefly grown in Bengal. Guaza is the name of 
the Bombay product which includes the wild plant. Both are 
used for smoking, and form the equivalent of the tobacco of 
western nations. Bhang, or ddee, consists of the dried leaves, 
fruit, and twigs of the wild plant. Its infusion is used as a 
beverage, as tea is in Europe and elsewhere. Hashish, made 
from bhang, corresponds to Extractum Cannabis Indicce, U. S. P. 
Charas or churras is a resinous exudation of the plant, and is also 
used for smoking. All these preparations are stimulating and 
narcotic. 4. Capsicum-fruit contains a resin (p. 477). 5. Castorin, 
a resinous matter, is the name given to the chief constituent of 
Casta?', the dried preputial follicles and included secretion of the 
Beaver (Castar Fiber). 6. Copal. — The best copal is the exuded 
resin of trees of extinct forests, and is found beneath the surface 
of the ground in the neighborhood of existing trees. It appears 
to be a mixture of acids, but its character is still obscure. 
Experiments by Wallach and Eheindorff" show that when copal is 
distilled, and the oily distillate washed with soda and distilled 
with steam, a mobile liquid boiling at 40°-350° C. is obtained. 
The lowest boiling portions of this liquid seem to contain iso- 
prene; the portions boiling at 154°-164° consist principally of a 
hydrocarbon of the composition C^oHig, which was proved to be 
pinene, and the fractions boiling at about 175° were found to 
contain dipentene. 7. Doundahe-bark, an African febrifuge, 
from Sarcocephalus esculentus, owes its activity to resinoid sub- 
stances, according to Heckel and Schlagdenhauffen. 8. Dragon's 
Blood is a crimson-red resin found as an exudation on the mature 
fruits of a Rotang or Eattan Palm {Calamus draco). According 
to Dieterich it contains a large proportion of aromatic esters, with 
dracoalban, Q.^^YL^f)^, dracoresen, C.^H^p^; ^^^ ^^^er substances. 
9. Ergotin, is a very active resinoid constituent of Ergot {Ergota, 
U. S. P.), i.e., the sclerotium (compact mycelium or spawn) of 
Claviceps purpurea, originating in the ovary of the common rye, 
Secale cereale. According to Wenzell, ergot contains two alka- 
loids, ecboline and ergotine, to the former of which, he says, the 
activity of ergot is due. Blumberg considers these alkaloids to bo 
identical. Tanret states that an unstable alkaloid termed 
ergotinine occurs in ergot to the extent of 1 per 1000 and that it is 



476 ORGANIC CHEMISTRY. 

accompanied by a camphor; also ergosterin, CjgH^^jO, HgO, 
resembling cholesterin. DragendorfFand Podwissotzki assert that 
ergot owes most of its activiy to sclerotic or sclerotinic acid, present 
to the extent of about 4 percent. Recent investigations seem to 
show that cornutine is an active alkaloid of ergot, associated with 
ergotinic and sphacelinic acids, picrosclerotine and ergotinine. 
The activity really seems to be due to a combination of alkaloids 
and acids, and not to any one constituent, as no principle repre- 
senting the full activity of ergot has been extracted. Ergot also 
contains choline, vfhich. by decomposition may yield trimethylamine, 
"JEi-gotin" {Extractum Ergotoe, U. S. P.), is obtained from ergot by 
extraction with alcohol (60 percent.), and purification of the 
product. 10. Guaiacum-resin {see p. 501). 11. Jalap-resin [see 
p. 502). 12. Kousso {Ousso, U. S. P.), yields yellow crystals of 
a resinoid substance readily soluble in alkaline liquids, kosin or 
koussin, C^^^fi^^. It is, perhaps, an anhydride. 13. Mastic is 
a resinous exudation obtained by incision from the stem of the 
Mastic or Lentisk tree. Nearly nine-tenths of mastic is mastichic 
acid, C20H32O3, a resin soluble in alcohol; the remainder consists 
of masticin, C2QH32O, a tenacious elastic resin, and a terpene having 
the formula CioH^g. 14. Mezereum, the dried bark {Mezereum 
U. S. P.) of Daphne Mezereum, Mezereon, Daphne laureola, 
Spurge Laurel, and of Daphne Gnidium, owes its acridity to a resin. 
15. Pe/J796'r contains resin (see p. 538). 16. Burgundy pitch i& ih.& 
melted and strained exudation from the stem of the Spruce Fir, 
Picea excelsa. The term Burgundy is ^ misnomer, the resin never 
having been collected in or near Burgundy; Finland, and to a 
small extent, Baden, and Austria being the countries whence it is 
derived. Its constituents closely resemble those of ordinary resin. It 
is often adulterated and imitated by a mixture of resin with palm- 
oil, water, etc., from which it may readily be distinguished by its 
duller yellow color, highly aromatic odor, greater solubility in 
alcohol, and almost complete solubility in twice its weight of 
glacial acetic acid (Hanbury). 17. Podophyllum-resin — In pre- 
paring the resin of podophyllum, or May-apple {Resina Podophylli, 
U. S. P.), an alcoholic extract of the rhizome and rootlets (Podo- 
phyllum, U. S. P., from Podophyllum pelfafum), is poured into 
acidulated water; the resin is then deposited. According to 
Guareschi, podophyllum contains a glucoside resembling con- 
volvulin. Podwissotzki has extracted from podophyllum a small 
quantity of crystalline coloring matter, fat, a bitter crystalline acid, 
a bitter crystalline neutral principle, and an amorphous acid resin. 
Kiirsten states that the latter yields a crystalline active substance, 
podophyllofoxin, Cg^H^^Oc, (Dunstan and Henry, Cj^Hj^O^) which 
seems to be the active principle both of Podophyllum peltatum, the 
U. S. drug and P. emodi, the Indian plant, 18. Pyrethrin is the 
acrid resinous active principle of the root of Anacyclus pyrethrum 
or Pellitory-root {Pyrethrum, U. S. P.). According to Buchheim, 



OLEOBESINS. 477 

alkalies break it up into piperidine and pyrethric acid. The crys- 
talline poisonous principle obtained by Bellesme from Pyrethrum 
carneum^ the powder of which (and P. roseum, and especially P. 
cineraricefolium, or Dalmatian Insect Powder) is the well-known 
** insecticide, " has not yet been analyzed. 19. The resins of 
Rhubarb. [See Chrysophanic Acid.) 20. Rottlerin, CggHg^Og, is 
the crystalline resin from Kamala, the minute glands that cover 
the capsules of Rottlera tinctoria: to this and, apparently, allied 
resins [isorottlerin, A. G. Perkin) Kamala owes its activity as an 
anthelmintic. 

Oleoresins. — 1. Oleoresin of aspidium [Oleoresina aspidii, 
U. S. P.), is obtained from the male fern [Dryopteris filix-mas) by 
exhausting the finely-powdered rhizome with acetone. 2. '^Cap- 
sicin,^' a term suggestive of a definite chemical substance, is a 
name somewhat unhappily accorded to an indefinite substance, an 
oleoresin {Oleoresina Capsici, U. S. P.), obtained by digesting 
Capsicum fruit {Capsicum, U. S. P.), in acetone. Besides volatile 
oil and resin, capsicum fruits contain much fatty matter which 
Thresh states is chiefly free palmitic acid. {See also Capsicine 
and Capsaicin, p. 531). 3. Copaiba {Copaiba, U. S. P.), is a mixt- 
ure of essential oil (CigHgJ, copaivaol, Q^^^^ (Strauss), with 2 or 
more percent, of brown soft resin, and 30 to 60 percent, of a yellow 
dark resin consisting mostly of copaivic acid, C20H32O2, with oxy- 
copaivic acid, C^qK^JJ^ (Fuhling), and mefacopaivic acid, G^^H^^O^ 
(Strauss). Copaiba, containing about equal parts of this acid and 
of the oil, heated with a fourth of its weight of theoflScial magne- 
sium carbonate, yields a transparent fluid, owing to the formation 
of magnesium copaivate and solution of this soap in the essential 
oil. With an equal weight of the carbonate, enough soap is 
produced to take up the whole of the essential oil, and form a 
mass capable of being rolled into pills. A much smaller quantity 
of calcined magnesia, as might be expected, effects the same result; 
but more time, often several days, is required before the inter- 
action is complete. Quicklime has a similar effect. Copaiba, 
unlike 4, Wood-oil or Gurjun Balsam, a similar oleoresin from 
Dipterocarpus turbinatus is almost entirely soluble in absolute 
alcohol and in petroleum spirit. Copaiba is often slightly fluo- 
rescent ; Gurjun balsam is highly fluorescent. The stated analogy 
of Gurjun balsam to copaiba is borne out by its chemical com- 
position; for by distillation it yields about 40 percent, of an 
essential oil identical in composition with oil of copaiba, the non- 
volatile portion being resinous. The adulteration of copaiba with 
fixed oil is best detected by heating 20 or 30 drops in a capsule 
until all essential oil has evaporated. (Turpentine is betrayed by 
its odor during this evaporation.) The residue, copaiba resin, is 
brittle if pure, and more or less sticky or soft if fixed oil is present. 
5. Oleoresin of cubeb, an alcoholic extract of cubeb decanted from 
waxy matter, is official, Oleoresina Cubebia, U. S. P. 6. Ehnni 



478 ORGANIC CHEMISTRY. 

is an exudation from a tree growing in the Philippine Islands. 
It consists of volatile oil (C^QHjg) with 80 or more percent, of two 
resins, the one {Q.^qH-^^O^) soluble in cold alcohol, the other, 
Amyrin, (C5Hg).,H20, almost insoluble, associated with Amyric 
acid, (C5Hg).0^ (Buri). There is an a- and a /3-amyrin, each hav- 
ing the formula Cg^H^gOH (Vesterberg). It also contains small 
quantities of two crystalline bodies soluble in water, Bryoidin, 
(C5Hg)^,3H20, and Breidm (Fliickiger). The Icacin of Stenhouse 
and Groves is either identical with amyrin, or perhaps has the 
formula (C.Hg)g, H,0. All these substances are probably hydrous 
terpenes. 7. Wood-tar {Piv Liquida, U. S. P.), is a mixture of 
several resinoid and oily substances (among others Creosote, see p. 
434) obtained by destructive distillation from the wood of Finus 
palusfrls and other pines. When heated, it yields a terebinthinate 
oil {Oleum Picls Liquidce, U. S. P.) and a residue of pitch. {Earth 
Pitch or Asphalte, appears to be a partially oxidized petroleum.) 
0/eum Cadinum, U. S. P. , " Htdle de Cade, ' ' or Juniper Tar Oil, 
is the product of the similar destructive distillation of Juniperus 
Oxycedrus. 8. Turpentines. — These oleoresins have been men- 
tioned in connection \vith oil of turpentine, their volatile constit- 
uent, and resin, their fixed constituent. 9. Common Frankincense 
is the concrete turpentine of Finus palustris and Finus tceda. 
10. Canada Balsam {Terebinthina Canadenis, U. S. P.), is largely 
gathered in the province of Quebec, and is the turpentine or oleo- 
resin of the Balm of Gilead Fir [Abies balsamea). 11. Sumbul- 
root {Sumbul, U. S. P.), contains 9 percent, of resin, to which 
probably it owes its stimulating properties. The resin consists of 
two parts, one soluble in ether and the other in alcohol, together 
with valeric, sumbulic, and sumbuolic acids. By dry distillation 
it yields a blue oil. 12. Oleoresin of Lupulin (Oleoresina Lupu- 
lini, U. S. P.) is an ethereal extract of the yellow glandular 
powder {Lupulinum, U. S. P.), attached to the small nuts at the 
base of the scales which form the aggregate fruit of the Hop 
{Humulus, U. S. P.). It contains a volatile oil which is chiefly 
composed of a sesquiterpene, an oxidized oil or resin, a bitter 
extract containing the hop-bitter, lupulinic acid, C.-H^^O^, and 
tannic acid. It generally contains a good deal of earthly dust, but 
should not yield more than 12 percent, of ash, and not more than 
40 percent, of matter insoluble in ether. 13. Oleoresin of Pepper 
{Oleoresina Piper is, U. S. P.), is obtained by exhausting powdered 
black pepper by percolation with acetone, removing the acetone by 
distillation and spontaneous evaporation, and straining through 
cotton to separate the oleoresin from the crystals of piperine that 
have been deposited. 14. Oleoresin of Ginger [Oleoresina Zingiberis, 
U. S. P.), is obtained from ginger, in powder, by exhausting it 
with acetone in a percolator and freeing the percolated liquid 
from acetone by distillation and spontaneous evaporation in a 
warm place. 



GU3I-RES1NS. 479 

Gum-resins. — 1. Ammoniacum is an exudation from Dorema 
Ammoniacum. It contains 20 percent, of gum, a little volatile 
oil, and 70 percent, of resin (C^oHggOg — Johnston). 2, Asafetida 
{Asafcetida, U. S. P. ), is a gum-resin obtained, by incision, from 
the living root of i^erw/a/oe^j(/a. It contains from 50 to 70 per- 
cent, of a resin which is partly ferulaic acid, C^qH^qO^, 25 to 30 
percent, of gum (about two-thirds arabin, one-third bassorin, 
p. 494), a little vanillin, and 3 to 5 percent, of volatile oil, which 
(Semmler) contains two sulphur compounds, C^H^^S2, and Cj^HjoSj, 
two terpenes, C^^H^g, and a sesquiterpene, O^^ii^^. 3. Euphor- 
bium, an old drug which is an emetic and purgative gum-resin, 
contains an amorphous active resin, crystalline eujphorhon, Cj^Hg^O, 
and other substances. 4. The ordinary or Siam Gamboge {Cam- 
bogia, U. S. P.), of European trade is obtained from the Garcinia 
Hanburii ; the gamboge of India from G. morella. When of best 
quality, it contains about 20 percent, of a gum, and 75 to 80 per- 
cent, of a yellow resin termed gambogic acid, Q^^^^O^. 5. Gal- 
banum consists of about 25 percent, of gum, about 65 percent, of 
resin, and 9 or 10 percent, of volatile oil. Moistened with alcohol, 
and then with hydrochloric acid, some varieties of galbanum yield 
a purple color. Galbanum heated for some time to 212° F. 
(100° C. ) with hydrochloric acid, the liquid separated and shaken 
with ether or chloroform, and the latter evaporated, yields some- 
what less than 1 percent, of colorless acicular crystals of umbelli- 
ferone, CgHgOg. According to Fliickiger and Hanbury, umbelli- 
ferone is soluble in water ; its solution exhibits, especially on 
addition of an alkali, a brilliant blue fluorescence which is 
destroyed by an acid. A small fragment of galbanum immersed 
in water, shows fluorescence on the addition of a drop of ammonia. 
The same phenomenon occurs with asafetida, and slightly with 
ammoniacum ; it is probably due to traces of umbelliferone pre- 
existing in these drugs. Umbelliferone is also produced from 
many other aromatic umbelliferous plants, as Angelica, Levisticum 
(Lovage, the basis of an old cordial or liquor), and Me^im, when 
their respective resins are submitted to dry distillation ; also from 
the resin of Daphne mezereum. The fluorescence of umbelliferone 
may be shown by dipping bibulous paper into water which has 
stood for an hour or two on lumps of galbanum, and drying it. 
A strip of this paper placed in a test-tube of water with a drop of 
ammonia will give a superb blue solution, instantly losing its color 
on the addition of a drop of hydrochloric acid. 6. Myrrh 
{Mijrrha, U. S. P.), an exudation from the stem of Commiphora 
Mijrrha, contains about half its weight of soluble arabinoid gum, 
10 percent, of insoluble gum (probably bassorin), 2^ of volatile 
oil, isomeric with thymol and carvone (Kohler), and about 25 
percent, of resin (myrrhic acid). 7. Olibauum ov Tims masculum, 
or Arabian Fraukincense (from various species of Boswc/fia is 
about one-third gum and nearly two-thirds resin (C^QH.,^Pg), with 



480 ORGANIC CHEMISTRY. 

a little hjTlrocarbon (C\oH,g) and oxidized hydrocarbon volatile 
oils. It has always been an imjiortant ingredient of incense — 
myrrh, storax, benzoin, and such fragrant combustible resinous 
substances, being other constituents. 8. Scammomj {see p. 505). 
Gum-resins need only to be finely powdered and rubbed in a 
mortar with water to yield a medicinal emulsion, in which the fine 
particles of resin are held in suspension by the aqueous solution 
of gum. 



QUESTIONS AXD EXERCISES. 



What are the general chemical characters of volatile oils?— How do vola- 
tile oils usually difler chemically from fixed oils?— Describe the usual 
process by which volatile oils are obtained.— How does natural turpentine 
differ from turpentine of trade ?— With what object is commercial turpen- 
tine rectified ?— What is the chemical nature of India-rubber and gutta 
percha?— How is India-rubber vulcanized and converted into ebonite or 
vulcanite?— ^Lention the difference in composition between the volatile 
oils of Anthemis nobilis and Matricaria ChamomiUa.—Giye the systematic 
name for oil of horse-radish.— State the general composition of the oils of 
lemon, hme, bergamot, citron, and cedra.—Xame the constituents of oil 
of cloves.— In what respect does otto of roses diff'er from other oils? — 
What class of substances forms the chief part of oil of rue ?— How is cam- 
phor-oil related to camphor ? — In what respects do Borneo or Sumatra 
camphor and camphor-oil diff'er from the corresponding products of Japan 
and China ? — How may Borneol be artificially prepared ? — How do resins 
occur in nature ? Distinguish between resins and camphors. Mention 
the points of difference of resins, oleoresins, gum-resins and balsams. — 
Name the sources of common resin or rosin. — Enumerate some official 
articles of which the active constituents are resins. — Give the distinguish- 
ing characters of Burgundy pitch. — What is the average proportion of oil 
and of resin in the so-called balsam of copaiba? — Explain the effect of 
magnesium carbonate, magnesia, and lime on copaiba. — Why doammonia- 
cum, asafetida, gamboge, galbanum. myrrh, and similar substances give 
an emulsion by mere trituration with water ? 



CARBOHYDRATES. 



Under the name carbohydrates there are grouped a large number 
of compounds containing carbon with hydrogen and oxygen in the 
same proportion as in water. They include sugars, dextrin, starch, 
cellulose, etc. The molecules of some of these are very comj^lex, 
but are resolved by hydrolysis into sugars such as glucose. 

The most commonly occurring carbohydrates contain six or 
multiples of six carbon atoms ; but analogous substances with three, 
five, seven, eight, or nine carbon atoms in the molecule are also 
known. 

The sugars are among the simplest of the carbohydrates. A 
large number of them, some identical with previously known 



I 



GLUCOSES 481 

natural sugars, some previously unknown, have been synthesized. 
They are partially oxidized polyhydric alcohols, having one of their 
alcohol groupings oxidized into an aldehyde or ketone group. For 
example, the trihydric alcohol glycerin, on oxidation with bromine 
in presence of solution of sodium- carbonate, yields glycerose, which 
has all the characters of a sugar. 

H H H H H .^ 

HC— C— CH+ 0=HC— C— Cf ^ + H,0 


H H H H H 

This, however, is not stable, but spontaneously condenses into a 
glucose, CpHj^20g. 

Erythrose, C^HgO^, is an example of a sugar with four, and 
arabinose, CgH^^O^, of one with five, atoms of carbon. Most of the 
natural sugars are glucoses (CgHj^Oj.) or compounds of two or three 
molecules of glucose minus water (bioses or trioses). 

Sugars with seven, eight, and nine atoms of carbon have been 
constructed by treating glucoses with hydrocyanic acid, which 
combines with the aldehyde or ketone group to form the nitrile of 
an acid containing one more carbon atom. This on hydrolysis 
gives the acid, the lactone [see p. 504) of which may be reduced 
in acid solution to the corresponding sugar by the action of sodium 
amalgam. This process is then repeated to get an eight-carbon 
sugar, and so on. One of these seven-carbon sugars was found to 
be identical with a natural sugar, perseite, but most of them have 
not yet been found occurring naturally. 

Glucoses, Cfi^fi^. 

Glucoses, CpH^Pg. There are two chief types of these six-car- 
bon sugars, differing from each other in the position of the alcohol 
grouping that has undergone oxidation, and classed accordingly as 
aldehyde and ketone sugars — aldoses and ketoses. Ordinary glu- 
cose, or dextrose is an example of the first class, Q.n^ fructose or 
loevulose of the second. Each of these classes contains a very large 
number of physical isomers, differing from each other in their 
action on polarized light and in some other respects ; these may be 
most readily distinguished from one another by means of the physi- 
cal characters of the compounds they form with phenyl-hydrazine 
{see p. 510). The large number of these isomers is accounted for, 
on the stereo- chemical theory, by the circumstance that there are 
no fewer than four asymmetrical carbon atoms {see]). 306) in each 
molecule. Thus there are three dextrose>s, dextro-rotatory, Ltvo- 
rotatory, and inactive ; three analogous mannoses ; three fructoses 
or laevuloses, etc. 

All the glucoses above mentioned have been obtained artificially, 
the starting-point being an artificial glucose {acrosc, C,.H,.,d,,) 
31 



482 ORGANIC CHEMISTRY, 

obtained by the condensation of formaldehyde — 6CH20=CgHj20g; 
it is probalDly in a similar way that natural sugars are produced by 
plants. 

Glucose (from yAvKvq, glucus, sweet), or Grape-sugar, or Dex- 
trose is often seen in the crystallized state in dried grapes or raisins 
and other fruits ; the sugar of diabetic urine, also, is one of the 
many glucoses. Its crystalline character is quite distinct from 
that of cane-sugar, the latter forming short monoclinic prisms, 
while grape-sugar occurs in masses of small six-sided plates. Grape- 
sugar is also less soluble in water, but more soluble in alcohol than 
cane-sugar. 

According to Fresenius, the percentage proportion of saccharine 
matter in the dried % is 60 to 70, grape 10 to 20, cherry 11, mul- 
berry 9, currant 6, whortleberry 6, strawberry 6, raspberry 4. 

Fructose, or Fruit-sugar, or Loevulose is the uncrystallizable, or 
very difficultly crystallizable, constituent of "inverted" cane- 
sugar. It is found in the grape, fig [Ficiis, U. S. P.), cherry, 
gooseberry, strawberry, peach, plum and other fruits, often with 
dextrose or with cane-sugar. Fruit-sugar reduces cupric salts and 
silver ammonium nitrate. 

Ordinary fructose is Isevo-rotatory, while sucrose and ordinary 
glucose are dextro-rotatory; the latter rotate a ray of polarized 
light to the right and the extent of the rotation varies with the 
amount of sugar present — a fact easy of application in determining 
the amount of sugar present in syrups or in diabetic urine. 

Artificial Formation of Grape-sugar from Cane-sugar. Test 
for Sugar. — Dissolve a grain or two of cane-sugar in water. 
To a portion of this solution placed in a test-tube add more 
water, two or three drops of solution of cupric sulphate, a con- 
siderable quantity of solution of potassium hydroxide (enough 
to turn the color of the liquid from a light to a dark blue), 
and heat the mixture to the boiling-point ; no obvious imme- 
diate change occurs. To another portion of the sugar solution 
add a drop of sulphuric acid, and boil for ten to twenty min- 
utes, then add the cupric solution and alkali, and heat as before; 
a yellowish-red precipitate of cuprous oxide, CUgO, is produced. 
This test is exceedingly delicate. 

The above reaction is due to the conversion of the cane-sugar, 
CJ2H22OJ1, into inverted sugar, ''^ a mixture of glucose and fructose, 

' The name inverted sugar originated from the fact that while a solution 
of cane-sugar rotates the plane of polarization of light to the right, the 
sense of the rotation is reversed, or " inverted," when cane-sugar ishydro- 
lyzed into glucose and fructose. Although the glucose so obtained is right- 
rotating and is equal in quantity to the fructose, yet the latter possesses 
left-rotating power to such an extent as to predominate over the right- 
rotation of the glucose, and a left rotating mixture results. 



r 



GLUCOSES. . 483 

by the influence of the sulphuric acid, and to the reducing action 
of the glucose and fructose on the cupric solution. The formation 
of a precipitate immediately, without the action of acid, shows the 
presence of the latter sugars — its formation only after ebullition 
with acid indicating, in the absence of starch or dextrin, cane-sugar. 
In this reduction-process the sugar is oxidized and broken up into 
several substances ; but the exact nature of the reaction has not 
been ascertained. 

Dextrin also reduces the cupric salt to cuprous oxide, unless its 
solution is cold and very dilute. It does not, however, so act on 
a solution of cupric acetate acidified with acetic acid, while glucose 
produces with this liquid the usual red cuprous precipitate (Bar- 
foed). 

Sugar from Starch. — Boil starch with a small quantity of 
water and a drop of sulphuric acid as in the preparation of dex- 
trin, but continue the ebullition for several minutes ; on testing 
a portion of the cooled liquid with iodine, and another portion 
with the heated alkaline solution of a cupric salt, as just 
described, it will be found that the starch has nearly all become 
converted into a sugar — glucose. Malose is also formed, at 
first, but by the continued action of the acid is changed to glu- 
cose. When made on a large scale, a warm (131° F., 51° C.) 
mixture of starch and water, of the consistence of cream, is 
slowly poured into a boiling solution of one part of sulphuric 
acid in one hundred of water, the whole boiled for some time, 
the acid neutralized by adding chalk, the mixture filtered, the 
liquid evaporated to a thick syrup and set aside; in a few days 
it crystallizes to a mass resembling solidified honey. In this 
operation a small quantity of dextrin remains with the glucose; 
but if the process be conducted under pressure, conversion, 
according to Manbre, is complete. Sugar made from the starch 
of rice, maize, etc., is largely used for table syrups, confection- 
ery, bee food, and as a partial substitute for malt in brewing. 
It is known as 'patent sugar, saccliarine, maltose, etc. 

In the United States the dealers term the syrups "glucose," 
and the further evaporated solid product ''grape sugar." The 
former contain one-third or more of glucose, about one-fifth of 
maltose, one-fourth or more of dextrin, and about one-sixth or 
one-fifth of water; the latter often contain about three-fourths of 
glucose, from none up to one-third of maltose, and one-seventh or 
one-sixth of water. 

Galactose (from milk-sugar), Sorbinose (from mountain-ash 
berries), Inosite (from muscle), llannose (from mannito), Gulose, 



484 ORGANIC CHEMISTRY. 

Fonnose, li-Acrose, Dambose (from a caoutchouc), and Scyllite 
(from many fish) are other glucoses. 

Saccharoses, or Bioses, Ci2H220n. 

Cane-sugar, or Sucrose {Saccharum, U. S. P.), is a- frequent con- 
stituent of vegetable juices. Thus it forms the chief portion of 
cassia pulp (from Cassia Fistula, U. S. P.), is contained in the 
carrot and turnip, but is most plentiful in the sugar-cane; much, 
however, is now obtained from the sugar-maple and beet-root. 
On evaporation of the juice, common brown or moist sugar crystal- 
lizes out; this bv re-solution, filtration through animal charcoal, 
evaporation to a highly concentrated syrup, and crystallization in 
moulds, vields the compact crystalline conical loaves known m the 
trade as " loaf-sugar. These loaves when broken mto fragments or 
sawn into cubes form lump- or cube-sugar. From a slightly less 
concentrated svrup, slowly cooled, the crystals termed sugar-candy 
are deposited, ' white or colored, according to the color of the 
syrup. The official syrup {Sijrupus, U. S. P.), is an aqueous 
solution. 

The sugar in fresh fruits is mainly cane-sugar ; but by the 
action of the acid, or possibly of a ferment in the juice, it is 
gradually converted into a mixture of glucose and fructose in 
varying proportions. Ripe Hips contain 30 percent, of such 
sugar, besides gum and acid malates and citrates. Sugar from 
flowers, as gathered in the form of syrup by bees, is probably a 
mixture of these two varieties. It is gradually altered to a crys- 
talline or granular mass consisting largely of glucose, as seen in 
dried fruits, such as Raisins and the Prune {Prunum, U. S. P.), 
and in solidified Honey. Honey, {Mel, U. S. P.), often contains 
pollen, hairs, spores, the dust from the flowers, and various floc- 
ciilent matters which cause it to ferment and yield mannite, alcohol, 
and acetic acid; hence for use in medicine it is desirable that a 
process of purification be adopted which yields clarified honey. 
Honey and cane-sugar are the bases of the official Confections. 

Maltose, ^^^^2^^^ — This crystallizable sugar is formed, together 
with dextrin, when diastase or dilute acids act upon starch. In 
the case of diastase it is the ultimate product, but the dilute acids 
may convert it into glucose. It differs also from glucose in its 
optical activity. 

Cane-sugar, maltose, and grape-sugar yield alcohol and carbonic 
anhydride by fermentation, the cane-sugar and the maltose appa- 
rently undergoing hydrolysis before the production of alcohol 
commences. 

In bread-making, some of the starch is converted into dextrin, 
and this into sugar by the ferment. The above action then goes 
on, the liberation of gas producing the rising or swelling of 
the mixture of flour, water, and yeast (dough). The temperature 



SACCHAROSES. 485 

to which the mass is subjected in the oven causes the escape of 
most of the alcohol, and the expansion of the bubbles of carbonic 
anhydride in every part of the now spongy loaf. The carbonic 
anhydride gradually evolved when flour is worked up for bread 
with a mixture of dry sodium bicarbonate and tartaric acid 
(best preserved by previous admixture with dried flour and 
a little magnesium carbonate) — baking-powder — exerts similar 
influence. The least objectionable method of introducing car- 
bonic anhydride, however, is that of Dauglish, whose patent 
aerated bread is made from flour by admixture with carbonic acid 
water under pressure by the aid of machinery. On removal from 
the cylinder, the resulting dough expands by the natural elasticity 
of the imprisoned carbonic anhydride, and the oven completes 
the process. All fermented bread retains, obviously, a little alcohol, 
sometimes 0.25 percent. 

Action of Alkali on Sugar. — To a solution of grape-sugar 
add solution of potassium or sodium hydroxide, or solution of 
potassium carbonate, and warm the mixture ; the liquid is 
darkened in color from amber to brown, according to the 
amount of grape-sugar present. A very little picric acid 
greatly intensifies the color. 

Tests. — The above, the copper-reaction, and the fermenta- 
tion process (p. 420) form three good tests for the presence of 
grape-sugar, and, indirectly, of cane-sugar. A piece of 
merino or other woolen material, previously dipped in a solu- 
tion of stannic chloride and dried, becomes of a brown or 
black color when dipped in a solution of glucose and heated 
to about 300° F, (about 150° C.) by holding before a fire. 

Barley sugar is made by heating cane-sugar with water until the 
whole is liquefied and then boiling off" the added water, a change 
from the crystalline to the vitreous condition occurring, with 
absorption of heat. The greater portion of confectioners' 
* ' sweets ' ' are formed of vitreous sugar. They slowly revert to 
the crystalline condition, with evolution of heat. Treacle Molasses 
or Melasses (from Mel, honey), or Golden Syrup, chiefly results 
from the application of too much heat in evaporating the syrups 
of the sugar-cane; it is a mixture of cane-sugar with uncrystal- 
lizable sugar and more or less coloring matter. Licorice-root 
[Olycyrrhiza, U. S. P.), contains much uncrystallizable sugar. 

Caramel — Heat a grain or two of sugar in a test-tube until it 
blackens and froths; the product is caramel, or burnt sugar (the 
Saccharum TJstum of pharmacy). It is used as a coloring agent 
for gravies, confectionery, spirits, vinegar, and similar materials. 
It is a mixture of substances, ''caramels" having slightly 
varying properties. 



486 ORGANIC CHEMISTRY. 

Milk-sugar, or Lactase, C^,^.^fi^^,H,f) (Saccharum Lactis, 
U. S. P.), the sweet priDciple of the milk of animals, is not 
susceptible of alcoholic fermentation by ordinary yeast ; certain 
species of saccharomyces, however, convert it into alcohol. It 
resembles grape-sugar in reducing an alkaline cupric solution 
with precipitation of cuprous oxide. It is obtained from milk 
by adding a few drops of acid, stirring, setting aside for the 
curds to separate, filtering, evaporating the whey to a small 
bulk, filtering again if necessary, and allowing to cool and 
crystallize. The deposited crude '' sngar-ssmd'' is afterward 
refined and recrystallized. Thus obtained milk-sugar has the 
formula above given, but if deposited from the hot solution 
during evaporation, the crystals are anhydrous, C^Ji^fi^^. 
Milk-sugar is convertible by the action of dilute acids, 
(hydrolysis) into galactose and glucose ; these may be made 
to interact to form milk-sugar. Powdered milk-sugar is used 
in pharmacy as a vehicle for potent solid medicines. The 
ofiicial article is met with in white hard crystalline masses or 
as a white powder, odorless, faintly sweet Soluble in 4.79 
parts of water at 25° C, and in 1 part of boiling water. It 
should not leave more than 0.25 percent, of ash when incin- 
erated with free access of air. A limit of ash is necessary as 
a test of purity, because magnesium carbonate of oxide, if 
added to neutralize the acidity of the whey during evapora- 
tion, as is sometimes done, gives rise to the presence of mag- 
nesium lactate in the milk-sugar, and this salt being converted 
into carbonate or oxide incineration, increases the amount 
of ash. 

Saccharic Acid, H^C.H^O,, or C,H,(OH)^(COOH),, is 
the product of the oxidation of sucrose, glucose, starch, gum, 
and lignin by nitric acid, Mannose yields manno-saccharic 
acid, isomeric with saccharic acid. Mucic acid, also isomeric 
with saccharic acid, may be obtained by the oxidation of lac- 
tose gum and dulcite. 



Melitose or Melitriose (from eucalyptus) is a triose, giving on 
hydrolysis galactose, glucose, and fructose. ^lelezitose (from the 
larch) and Ti^ehalose (from Turkish manna), belong to the Saccha- 
roses. 

'■'■Honey-dew'''' is a viscid saccharine matter occasionally met 
with on the leaves of the lime, maple, black alder, rose, and other 
trees, being a sweet })rinciple exuded from aphides. Sometimes 
it is sutficiently abundant to dry and fall on the ground, forming 



A3£YL0SIS OR AMYLOIDS. 487 

a veritable ''shower of manna." It is a mixture of cane-sugar, 
inverted sugar, and dextrin. 



QUESTIONS AND EXERCISES. 

Into what three classes may the carbohydrates be divided ? How is 
grape-sugar obtained from cane-sugar?— How are cane-sugar and grape- 
sugar analytically distinguished ?— How is dextrose obtained from starch? 
—Mention the chief sources of cane-sugar.— Give chemical explanations 
of the processes of bread-making.— What is the difference between fruit- 
sugar and honey ?— Describe the effect of heat on cane-sugar.— How is 
milk-sugar obtained, and how does it differ from other sugar ?— How may 
mucic and saccharic acids be obtained ? 



Amyloses, or Amyloids, nCJl^fi^ 

Starch, nCgHioOg, is contained in large or small quantities 
in nearly every plant. It forms about 60 to 70 percent, of 
wheat, and from 20 to 30 percent, of potatoes. The starch 
officially recognized in the Pharmacopoeia (Amylam) is that 
of maize (Zea Mays). 

Experiment. — Rasp or grate, or scrape with a knife, a por- 
tion of a clean raw potato, letting the pulp fall on to a piece 
of muslin placed over a small dish or test-glass, and then pour 
a slow stream of water over the pulp ; minute particles or 
granules pass through the muslin and sink to the bottom of 
the vessel, fibrous matter remaining on the sieve. The gran- 
ules consist of potato starch. Even diseased potatoes furnish 
good starch by this method. Wheat-starch may be obtained 
by tying up some flour in a piece of calico, and kneading the 
bag in a slow stream of water flowing from a tap, the wash- 
ings running into a deep vessel, at the bottom of which the 
starch collects ; the sticky matter remaining in the bag is 
gluten. 

The blue starch of the shops is artificially colored with smalt or 
indigo, to neutralize the yellow tint of recently washed linen ; it 
should not be used for medicinal purposes. Starch dried in mass 
splits up into the familiar columnar masses in which the commer- 
cial article is met with. 

Gluten is the substance which gives tenacity to dough and bread. 
It seems to be a mixture of vegetable fibrin, vegetable casein, and 
an albuminous matter termed glutin. Each of these bodies con- 
tains about 16 percent, of nitrogen. In the anhydrous condition 
gluten consists of carbon 52.6 percent., hydrogen 7 percent., nitro- 



488 ORGANIC CHEMISTRY, 

gen 16 percent., and oxygen, with a trace of sulphur, 24.4 per- 
cent. Wheaten Flour contains about 72 percent, of starch and 
11 of gluten, as well as sugar, gum, fine bran, water, and ash. 
The compactness of barley, well seen in Hmked or Pearl Barley, 
is said to be due to the large amount of vegetable fibrin present. 
During germination the fibrin is destroyed ; hence, probably, the 
cretaceous character of malt. Oatmeal, popular when made into 
' 'jDorridge, " is rich in albuminoids, or flesh-forming constituents, 
containing nearly 16 percent. Sago is granulated starch from the 
Sago Palm ; tapioca from the Bitter Cassava ; each has less than 
1 percent, of albuminoids. The white translucent Rice grains are 
the husked seeds of Oryza sativa. Rice is a staple article of food in 
tropical countries. Ground rice {Oryzce Farina), resembles flour 
of wheat in composition, but contains from 85 to 90 percent, of 
starch. 

Mucilage of Starch. — Mix two or three grains of starch 
with first a little and then more water, and heat to the boil- 
ing point ; starch mucilage results. This mucilage or paste is 
not a true solution ; by long boiling, however, a portion of 
the starch becomes dissolved. In the latter case the starch 
probably becomes somewhat altered. 

Test. — To some of the mucilage add a very little fi-ee iodine; a 
deep-blue color is produced. This reaction is a very delicate test 
for the presence of either iodine or starch. The starch must be 
in the state of mucilage ; hence in testing for starch the substance 
supposed to contain it must first be boiled with water. The solu- 
tions used in the reaction should also be cold, or nearly so, as the 
blue color disappears on heating, although it is partially restored on 
cooling. The iodine reagent may be iodine- water or tincture of 
iodine. In testing for iodine, its occurrence in the free state must 
be ensured by acidulation if necessary, and the addition of a drop, 
or even less, of chlorine-water. Excess of chlorine must be 
avoided, or iodic acid will be formed, which does not color starch. 

The so-called iodide of starch scarcely merits the name of a 
chemical compound, the state of union of its constituents being 
so feeble that it is decomposed at 100° F. (37.7° C), while sub- 
stances which attack free iodine remove that element from it. 
Thus the alkalies, hydrogen sulphide, sulphurous acid and other 
reducing agents, destroy the blue color. Dry starch will absorb, 
according to its source, from 6 to S percent, of iodine ; but in the 
state of mucilage three times the quantity. There are probably 
three definite compounds of starch with iodine. With nitric acid, 
starch yields an explosive compound {Xyloidin) Oy^^^O^Q^O^^. 
Two isomeric tetranitro-derivatives, as well as a penta- and a hex- 
anitro-derivative, are known. 



■} I 



STARCH. 



489 



Composition of /Starch Granules. — Starch granules consist mainly 
of granulose, soluble in cold water and giving an indigo color with 
iodine, and starch cellulose, insoluble in water and giving with 
iodine a dirty yellow color, with, possibly, other carbohydrates. 
The starch cellulose forms an external coating upon the granule, 
and also exists mixed with the granulose inside the granule. If 
this coating be broken by mechanical means, the continued appli- 
cation of cold water removes all the granulose, leaving the cellu- 
lose insoluble. By the action of diastase, ptyalin, and other fer- 
ments, and by other means, the granulose may be converted into 
sugar and dextrin, leaving the starch cellulose unacted upon. 

Microscopic Examination of Starches. 

All kinds of starch aiford the blue color with iodine, showing 
their chemical similarity. Physically, however, the granules of 
different starches differ from each other ; hence a careful micro- 
scopic examination of any starch, or of any powder or vegetable 
tissue containing starch, enables the observer to state, with a high 
degree of probability, the source of the starch, either at once if 
he has much experience, or after comparing the granules in ques- 
tion with authentic specimens. (A glance at the accompanying 
eight engravings^ of common starches will show to what extent 
different starch granules differ naturally in size, shape, general 
appearance, distinctness and character of the rugce, and position 
of the more or less central point of hilum). While from different 
starches individual granules may be picked out which much resem- 
ble each other, the appearance of each starch as a whole is fairly 
characteristic; that is to say, each group oi granules differs in one 
or more characters from similar groups of granules of other starches. 

A quarter-inch object-glass will commonly suffice for the micro- 
scopic examination of starch. A very little of the starch is mixed 
on a glass slide with a drop of water, and a piece of thin covering- 
glass placed on the drop and gently pressed, so as to provide a 
very thin layer for observation. Instead of water, diluted alcohol, 
diluted glycerin, turpentine or other essential oil, Canada balsam, 
and other fluids may be used in cases where the markings or 
other appearances are not well defined. The illumination also of 
the granules may be varied, the light being reflected or trans- 
mitted, concentrated or diffused, white or colored, polarized or 
plain. Polarized light is especially valuable in developing differ- 
ences, and in intensifying the effects of obscure markings. By 
polarized light the granules of potato starch appear as if trav- 
ersed by a black cross; wheat starch granules and many others 
also peculiarly and characteristically influence polarized light. 
Distinctive characters will sometimes present themselves only 

^ By permission of Messrs. Longmans & Co., these engravings have 
been copied, with very few modifications, from the plates in two of the 
three vohimes of the original edition of Pereira's " Materia Medica." 



490 



ORGANIC CHEMISTRY, 



STARCHES. 

(Magnified 250 diameters.) 



'--250^ of an inch 



Figs. 42 to 49. 




INULIN. 491 

when the granules are made to roll over in the fluid in which they 
have been temporarily mounted, or when the slide is gently 
warmed. Starches which have already been subjected to the in- 
fluence of heat, partly, as in sago or tapioca, or almost entirely, as 
in bread, will of course differ in appearance from granules of the 
same starch before being dried, cooked, or torrefied. The char- 
acters of a starch will also vary somewhat according to the age 
and condition of the plant yielding it. 

The description of the microscopic characters of some varieties 
of starch^ is as follows : — 1. Wheat starch : A mixture of large 
and small granules, the former lenticular in shape, and marked 
with faint concentric striae surrounding a nearly central hilum. 

2. Maize starch : Granules more uniform in size, frequently polyg- 
onal, somewhat smaller than the large granules of wheat starch, 
and having a very distinct hilum but no evident concentric striae. 

3. Rice starch : Granules extremely minute, nearly uniform in 
size, polygonal, and without evident hilum or strise. 

The student may place fair confidence in the accompanying 
illustrations, and in most of the published engravings of starch 
granules ; but in microscopic analyses of importance the worker 
should, if possible, himself obtain actual specimens of starches 
for comparison from the respective seeds, fruits, and other tissues. 

Inulin, GCgHjoO., H^O (Kiliani), occurs with similar substances, 
pseudo-inulin, 160^11^^0 ^,lifi, and inulermi, lOC^^HioOg, SH^O 
(Tanret). It is a white powder apparently occupying the place of 
starch in the roots of many plants, especially those of the natural 
order Composit(je. Twenty to forty-five percent, has been obtained 
from elecampane {Inula heleniwn). It is also contained in the 
dahlia, colchicum, arnica, dandelion, chicory, artichoke, etc. It 
is soluble in boiling water, nearly all being re-deposited on cool- 
ing. Iodine turns it yellow. Long ebullition converts it into a 
kind of gum. Like starch, inulin is convertible into sugar, but 
by its own special ferment, the existence of which in the Jeru- 
salem Artichoke has been demonstrated by J. R. Green. This 
ferment differs from diastase in being without the power of con- 
verting starch into sugar. 

Lichenin, nOJi^QO^, is a white starch-like powder largely con- 
tained in many lichens — Iceland "Moss," Cefraria Islandica, and 
many others. It is soluble in boiling water, and the fluid gelatin- 
izes on cooling. It may be precipitated from its aqueous solution 
by addition of alcohol. With iodine it gives a reddish-blue color. 

Glycogen, or animal starch, is the name given to the solid matter 

^ For plates and descriptions of the characters of other starches occur- 
ring in plants used for medicinal purposes, the reader is referred to works 
on Materia Medica, and to the indexes of Journals of PharnKU'v. as well 
as to general works and magazines on microscopy. For engravings of 
starch granules m sifu, see Berg's "Anatoniischer Atlas," published hy 
Gaertuer. Berlin. 



492 ORGANIC CHEMISTRY. 

stored in the liver and resulting from the dehydration of the 
digested hydrated food which has been carried to the liver by the 
portal vein. 

Dextrin, nCfi^fi^. — Mix a few grains of starch with half 
a test-tiibeful of cold water and a drop or two of sulphuric 
acid, and boil for a few minutes ; no thick mucilage is formed, 
and the liquid, if sufficiently boiled, yields, on cooling, no blue 
color with iodine ; the starch has become converted into dex- 
trin and sugar. Dextrin is also produced if starch is main- 
tained at a temperature of about 320° F. (160° C.) for a 
short time. Dextrin is largely manufactured in the latter 
way, and a paste of it is used by calico printers as a vehicle 
for colors ; it is termed British gum. The change may also 
be eifected by diastase, a peculiar ferment existing in malt. 
Mix two equal quantities of starch with equal amounts of 
water, adding to one a little ground malt, then heat both 
slowly to the boiling-point ; the mixture without malt thickens 
to a paste ; that with malt remains thin, its starch having be- 
come converted into dextrin and maltose. 

Diastase is probably a mixture, but possibly an oxidation prod 
uct, of the coagulable albuminoids. It is so named from didaraaig 
(diastasis) separation, in allusion to the separation, or rather altera- 
tion, it effects among the constituent atoms of the molecule of 
starch. This function is shared by the saliva, pancreatic juice, 
bile, and the intestinal and other juices. The function is com- 
pletely destroyed when the albuminoids are coagulated by a tem- 
perature of from 176° to 178° F. (80° to 81° C). 

The Action of Diastase upon Starch. — Diastase has scarcely any 
action upon unbroken starch granules. The granules must be 
ruptured by gelatinization with heat and moisture, or in some 
other way. When a solution containing diastase, such as a cold 
water infusion of malt, is allowed to act upon gelatinous starch or 
starch-paste at 140° to 160° F. (60° to 71° C), liquefaction occurs. 
It is possible to operate so that when liquefaction has taken place, 
the solution shall give no reaction for sugar or dextrin. If this 
solution be concentrated and allowed to cool, a glistening white 
precipitate of soluble starch falls. Soluble starch is probably the 
result of the partial decomposition of the more complex molecule 
of granulose or gelatinous starch. The next step in the action of 
diastase upon gelatinous starch is the breaking down of the solu- 
ble starch molecule into dextrin and maltose. At least ten dex- 
trins are successively produced, each simpler than the one preced- 
ing it, the proportion of maltose being correspondingly increased. 
The dextrins first produced give a red or brown color with iodine, 



MALT. 493 

while those last produced, and having a simpler molecule, give no 
color with iodine. The final reaction may be expressed thus : — 

10(C,,H,,0,o) + 8H,0 = 8(C,,H,,O,0 + 4.{C,U,,0,) 
Soluble starch Maltose Dextrin 

The dextrins are distinguished by their rotatory power, their reduc- 
ing action on cupaic salts, and in other ways. 

Starch heated with glycerin is converted into the soluble variety. 
The latter may be precipitated from an aqueous solution by strong 
alcohol. A concentrated solution in water gradually gelatinizes, 
owing to reconversion into insoluble starch (Zulkowsky). 

The Action of Dilute Acids upon Starch. — Dilute acids act upon 
gelatinous starch in the same way as diastase, except that the final 
product is glucose. 

Malt {Maltum, U. S. P.), (the word malt is said to be derived 
from Welsh mall, soft or ' 'rotten' ' ) is simply barley which has been 
softened by steeping in water, and allowed to germinate slightly, 
any further change being then arrested by the application of heat 
in a kiln. During germination the gluten breaks up and yields a 
glutinous substance termed vegetable gelatin, diastase, and other 
matters. To the vegetable gelatin is due much of the ' ' body ' ' of 
well-malted and slightly-hopped beer ; it is precipitated by tannic 
acid ; hence the thinness of ale (pale or bitter) brewed with a large 
proportion of hops or other material containing tannic acid. A 
portion of the diastase reacting on the starch of the barley con- 
verts it into dextrin, and, indeed, carries conversion to the further 
stage of maltose, as will be explained immediately. The tempera- 
ture to which the malt is heated is made to vary, so that the sugar 
of the malt may or may not be partially altered to a dark-brown 
coloring material ; if the temperature is high, the malt is said to 
be high-dried, and is used in porter-brewing ; if low, the product 
is of lighter color, and is used for ale. The diastase remaining in 
malt is still capable of converting a large quantity of starch into 
dextrin and maltose ; hence the makers or distillers of the various 
spirits operate on a mixture of malted and unmalted grain in pre- 
paring liquors for fermentation. 

Extract of 3Ialt {Extractum Malti, U. S. P.), is an evaporated 
infusion of malt. Taken with food, its. diastase aids in the con- 
version of starch into maltose and dextrin, and, pro tanto, assists 
enfeebled digestive powers. 

3C«H O, + HP = C„H,,0„ + C,H,,0, 

starch Maltose Dextrin 

As diastase begins to lose this power at temperatures above 150° 
F. (55.5° C), that limit should not be exceeded in evaporating 
the infusion ; indeed, if the dissolved albuminoid matters are to 
be retained, the evaporation should be conducted at 120° F. 
(18.8° C). 



494 ORGANIC CHEMISTRY. 

The following method serves for the determination of the 
diastasie power of malt extract: — 1.5 grammes of extract are 
dissolved in 15 Cc. of water and mixed with a mucilage of 
0.1 gramme of starch in 100 Cc. of water. The mixture is 
raised to 140^ F. (60° C.) and tested from time to time by 
adding two drops of iodine solution to 5 Cc. of it, and com- 
paring with 5 Cc. of a similar mixture to which no starch has 
been added. If the two solutions do not exhibit any differ- 
ence of tint this indicates the completion of the reaction. 
Good malt extract will accomplish this within half an hour, 
some samples will take less time, but many commercial 
extracts will require three hours or more. 

Gum is a frequent constituent of vegetable juices, existing in 
large quantity in several species of Acacia. The nature of gums 
is very little known, though most probably they all belong to the 
carbohydrates. According to Fremy, gum contains a calcium 
salt (sometimes also a potassium salt) of the gummic or arable 
radical, though consisting mostly of arabin or arable acid alone. 
The formula of gummic acid is said to be H2Cj2H^gOjQ,H20, but 
from the important researches of 0' Sullivan, it would seem to be 
far more complex, a multiple of the empirical formula CgH^gOj — 
according to Raoult (CgH^QO^).. Gum differs from dextrin in 
yielding mucic acid when oxidized by nitric acid. Good adhesive 
mucilages may be made from such gum-arabic substitutes as 
''ghatti," ''amrad," etc. /«(/k/i G^wm is an exudation from the 
wood of Anogeissus latifoUa.' It has double the mucilaginous 
strength of Gum Acacia {Acacia, U. S. P.). Cerasin or cherry- 
tree gum is calcium metagummate, an insoluble modification of 
acacia gum. Bassorin, traganthin, or adragaufhin, C,2ll2o^io» ^^ ^ 
form of gum which is insoluble in water, but absorbs large quanti- 
ties of that liquid and forms a jelly-like mass : it occurs largely 
in Tragacanth, combined, like arabin, with, calcium. Pectin, or 
Vegetable Jelly, C.^^H^fi^^, 411,0, is the body which gives to 
expressed vegetable juices the property of gelatinizing : it forms 
the chief constituent of Irish or Carrageen "Moss" {Chondriis, 
U. S. P.). Ceylon '' ^loss^' contains from one-third to three- 
fourths of vegetable jelly. Many seaweeds yield a jelly when a 
decoction of them is cooled. The Japanese freeze the jelly of 
GeUdium corneum and then cut it into strips ; these slowly dried 
form the so-called Japanese isinglass, Chinese 3hss, or gelose of 
Payen, It is probably a carbohydrate. With Avater, it is said 
to give a jelly 10 times stronger than that obtained from gelatin. 

The mucilage of marsh-mallow root {Althea, U. S. P.), and of 
linseed or common flax-seed (Linum, U. S. P.), is a gum-like sub- 
stance containing much mineral matter. It is the basis of the 
infusions termed mallow-tea and linseed-tea. Somewhat similar 



DINITROCELLULIN. 495 

mucilage occurs in Bael Fruit, the fresh half- ripe fruit of ^gle 
Marmelos. It is also largely yielded by the seeds of the Quince 
{Pyriis Cijdonia). Salep, the powdered dried tubers of many 
species of Orchis, contains a large quantity of such matter, as also 
does Squill The Indian Ohm and Ispaghul or Spogel seeds also 
appear to contain a considerable quantity. 

Cell id in, or cellulose, nC^U^^O^, the woody fibre of plants, famil- 
iar, in the nearly pure state, under the forms of ' ' cotton wool ' ' 
{Gossijpium Purificatum, U. S. P.), hairs of the seed of various 
species of Gossypium), paper, linen, and pith, is another substance 
isomeric, probably polymeric, with starch. Lignin is a closely 
allied body, lining the interior of the woody cells and vessels of 
plants. By the action of nitric acid of various degrees of concen- 
tration on cellulin, di-, or tri-nitrocellulins, and possibly others, 
are readily formed :—nQ^^fi.ii:^0^)^ ; ^C.H^O^lNOgJs. Trinitro- 
cellulin is highly explosive gun-cotton ; dinitrocellulin is not 
sufiiciently explosive for use instead of gunpowder. Mononitro- 
cellulin has not been so thoroughly examined as the others, but is 
said to be scarcely at all explosive ; its formula is nCgHgO^NOg. 
The heat of a water-bath may explode trinitrocellulin, but not 
dinitrocellulin if pure. The three displaceable hydroxyl groups 
in cellulin may be displaced by groups other than the nitric 
radical. 

Dinitrocellulin (Pyroxylinum, U. S. R), may be prepared 
by the following official process : — Mix 5 fluid ounces of sul- 
phuric acid and 5 of nitric in a porcelain mortar, immerse 1 
ounce of cotton-wool in the mixture, and stir it for three min- 
utes with a glass rod, so that it is thoroughly and uniformly 
wetted by the acids. Transfer the cotton to a vessel contain- 
ing a considerable volume of water, stir it rapidly and well 
with a glass rod; decant the liquid, pour more water upon the 
mass, agitate again, and repeat the affusion, agitation, and 
decantatiou until the washings no longer give a precipitate 
with barium chloride. Drain the product on filter-paper, and 
dry on a water-bath. 

Pyroxylin may also be made by soaking 7 parts of white filter- 
paper, which has been washed in hydrochloric acid and dried, in 
a mixture of 140 parts of sulphuric acid (sp. gr. 1.82) and 70 of 
nitric acid (1.37) for three hours, and well washing the product 
(Guichard). 

Trinitrocellulin or gun-cotton is insoluble in a mixture of alco- 
hol and ether ; dinitrocellulin or pyroxylin is soluble, the solution 
forming ordinary collodion {Collodiuni, IT. S. P.). The official 
])roportions are 40 grammes of pyroxylin dissolved in a mixture 
of 750 Cc. of ether and 250 Cc, of alcohol. After digesting for a 



496 ORGANIC CHEMISTRY. 

few days, decant the liquid from any sediment and preserve it in 
a well-corked bottle. It dries rapidly upon exposure to air, and 
leaves a thin transparent film, insoluble in water or alcohol. 
Flexible collodion [Collodium Flexible, U. S. P.), is a mixture of 
collodion (92 parts), Canada Turpentine (5 parts), and castor oil 
(3 parts). Cantharidal Collodion {Collodium Cantharidafnni, 
U. S. P.), is a solution of the active blistering principle of can- 
tharides in flexible collodion. Many articles of utility and beauty 
are now made of pyroxylin variously colored and sold under the 
name of xylonite {^vlov, xulon, wood) or celluloid. 

Tunicin, or animal cellulose, exists in the mantle of Ascidia. 



QUESTIONS AXD EXEECISES. 

How is wheat-starch or potato-starch isolated ?— Define gluten and glu- 
tin. — Enumerate the proximate principles of wheaten flour. — Is starch 
soluble in water ? — Which is the best chemical test for starch ? — Distin- 
guish physically between the varieties of starch. — Into what compound is 
starch converted by heat?— What occurs when a mixture of starch and 
water is allowed to flow into hot dilute sulphuric acid ? — Describe the 
difierent results of heating starch with water alone, and with water and 
a small quantity of ground malt. — Write a short article on the chemistry 
of malting. — What is the nature of gum arable, and how is it distinguished 
from " British gum " ? — Mention the properties of the products of the 
action of nitric acid of various degrees of concentration on cellulin. — How 
is pyroxylin prepared ? 

GLUCOSIDES. 

Source. — The glucosides are certain vegetable principles which, 
by ebullition with dilute acid, or by other treatment, take up the 
elements of water {i.e., undergo hydrolysis) and yield glucose, 
accompanied by a second substance, which differs' in each case 
according to the glucoside operated on. Some of the glucosides 
may be regenerated from the substances into which they are con- 
verted by hydrolysis. Tannin, which has already been described 
among the acids, is held by some authorities to be a glucoside. 

Mfe on Nomenclature. — The first portion of the names of glu- 
cosides and neutral principles generally is commonly given in 
allusion to origin ; the last syllable is in. 

The following paragraphs deal with the glucosides and with a 
few other non-alkaloidal vegetable principles which are of pharma- 
ceutical interest and importance. 

Absixthin, Cj.H^oO,, the bitter principle of Artemisia Absin- 
thium, or wormwood, yields, when boiled with acids, glucose, 
volatile oil and a resin of the aromatic series. (The liquor 
termed absinthe is ethyl alcohol (of varying strength) flavored with 
natural oil of wormwood, colored by chlorophyll, and slightly 
sweetened. ) 



GLUCOSWES. 497 

Amygdalin, CgoH^.NOjpSHgO. This substance, obtained by 
Robiquet and Boutron-Charlard in 1830, was the first discovered 
glucoside (Liebig and Wohler, 1837). It is a white crystalline 
substance, existing in the bitter almond [Amygdala Amara, 
U. S. P.), but not in the sweet {Amygdala Dulcis, U. S. P.), 
About 2 percent, is readily extracted by strong alcohol from the 
cake left when the fixed oil has been expressed from bitter 
almonds. From the concentrated alcoholic solution ether precip- 
itates the amygdalin. 

Experiment. — Make an emulsion of two or three sweet 
almonds by bruising and rubbing them with water, and notice 
that it has no odor of essential oil of bitter almonds ; add a grain 
or two of amygdalin : an odor of essential oil of bitter almonds 
is at once developed. Bruise two or three bitter almonds and 
rub with water : the volatile oil is again developed. 

The source of the benzaldehyde, or essential oil of bitter almonds, 
in these reactions, is the amygdalin, which, under the influence 
of synaptase or emulsin (a nitrogenous, casein-like ferment existing 
in bitter and sweet almonds), splits up into benzaldehyde, hydro- 
cyanic acid, and glucose : — 

C,oH,,NOj, + 2Hp = C.H.COH + HCN + 2C,H,,0, 

Amygdalin Water Benzaldehyde Hydro- Glucose 

cyanic acid 

As each molecule of amygdalin yields one of hydrocyanic acid, a 
simple calculation shows that 17 grains (mixed with emulsion of 
sweet almonds, Emulsum Amygdake, U. S. P.), will be required to 
form one grain of hydrocyanic acid. The hydrocyanic acid is prob- 
ably in chemical combination with the oil, to the extent of about 
5 percent. According to Lindo, the production of the benzalde- 
hyde is preceded by the formation of benzaldehyde-cyanhydrin, 
CpH.CH(OH)CN. The emulsion and amygdalin occur in different 
parts of the bitter almond. Aqua Amygdalce Amarw, U. S. P^, is 
made from the essential oil, which therefore is also included in the 
U. S. P. 

Test. — The reaction between synaptase and amygdalin is appli- 
cable as a test for the presence of one by the addition of the other, 
even when mixed with much organic matter. 

When amygdalin is warmed with fuming hydrochloric acid, 
mandelic, or phenylglycollic acid, C^Hg.CHOH.COOH, is pro- 
duced. 

Cherry Laurel Water, prepared by distillation with water from 
Laurocerasi Folia contains hydrocyanic acid derived from a reaction 
similar to, indeed probably identical with, that described above, 
for bitter almond oil is simultaneously produced. But the pro- 
portion of amygdalin or analogous substance in cherry-laurel leaves 
32 



498 OBGAXIC CHEMISTRY. 

is most variable ; hence the quantity of hydrocyanic acid in the 
distillate is yariable. 

Linseed yields a glucoside, linamarin, related to amygdalin, for 
it affords glucose and hydrocyanic acid on hydrolysis, 

Frunus Virginiana. -^This, the recently dried bark of Prunus 
serotina, furnishes by distillation an essential oil and hydrocyanic 
acid as also do the seeds of the Quince {Pyrus Cydonia). The Wild 
Black Cherry, collected in autumn, contains amygdalin. 

Caution. — Essential oil of almonds is of course highly poisonous. 
The purified oil or benzaldehyde is almost innocuous ; it is obtained 
on distilling the crude oil with milk of lime and ferrous chloride, 
and drying the product by shaking with fused calcium chloride. 
The so-called " artificial oil of bitter almonds" or nitrobenzene, 
CgHgXOg, when taken in quantity, has been known to produce 
death. The presence of nitrobenzene in oil of bitter almonds is 
detected by adding a little of the oil to a mixture of zinc and dilute 
sulphuric acid, shaking well, setting aside for an hour or two, 
filtering off the clear liquid, which now contains phenylamine, or 
aniline, and adding some potassium chlorate; a violet color is pro- 
duced, due to the oxidation of the aniline with formation of ani- 
line mauve {see p. 555). Or the specimen may be shaken with 
sodium bisulphite to fix the benzaldehyde (for all such aldehydes 
form a compound with sodium bisulphite), and then with ether, 
which dissolves out, and on evaporation will yield, the nitroben- 
zene. 

Arbutix, CjjH^fiO., and mefhyl-arbn.tin, C^gH^gO., are contained 
in the leaves of Arctostaphylos Uva Ursi, Chimaphila umbellata 
{Chimaphila, Y. S. P.), and many ericaceous plants. Arbutin is 
a neutral substance occurring in acicular crystals, and resolvable 
by acids into hydroquinone, CgH^O,, and glucose, and by gentle 
ox.\([?ii\o\\ mto qui7ione, C^H^Oo, and formic acid. Ericolin, Cg^H-gOgj, 
is another bitter glucoside in bear-berry leaves. 

Cathaetic Acid. — The name cathartic acid was given by 
Dragendorffand Kubly to the glucoside-acid to which the purga- 
tive properties of Alexandria and India Senna (Senna, U. S. P. ), 
appear to be chiefly due. Genz states that the formula for the 
acid is C^pH^^yO^j. The acid itself, which is obtained in the form 
of a black mass, is described as insoluble in water, alcohol, and 
ether, while its alkali-metal and other salts which occur in senna 
are readily soluble. Dilute alkalies dissolve it, yielding solutions 
from which it is reprecipitated on adding an acid. Its ammonium 
salts give brownish flocculent precipitates with salts of silver, tin, 
mercury, copper, and lead. When boiled with dilute acids, 
cathartic acid undergoes hydrolysis, yielding cathartogenic acid 
and glucose. 

Buclihorn Juice {Fluidextractum Frangake, U. S. P.), owes its 
cathartic properties to a substance apparently identical with 
cathartic acid. 



GLUCOSIDES. 499 

COLOCYNTHIN, O^^fi^P^r — ^^^^ substance is the active bitter 
and purgative principle of colocynth-fruit {Colocynthia, U. S, P.); 
it is soluble in water and alcohol, but not in ether. By ebullition 
with acids it furnishes glucose and a resined substance. 

CONVOLVULIN. — See Jalapin. 

COTOIN, Cj^H^gO^, appears to be the chief active principle of 
Goto bark, a Bolivian remedy for diarrhoea. A similar bark, false 
coto, or paracoto, contains paracotoin, Q^^fi^, and hydrocotoin, 

Daphnin, C^gH^gOg, is the crystalline glucoside of the bark of 
Daphne Mezereum {Mezereum,\] . S. P.). Boiled with dilute acids, 
it yields daphnetin, CgHgO^, and glucose. The acrid principle of 
mezereum is resinoid. 

Digit ALiN, C^HgO^, Schmiedeberg ; CggHggO^^, Kiliani.— This 
is an active principle of the Foxglove, Digitalis purpurea. Three 
different glucosides have been prepared from the leaves and seeds 
of digitalis : — digitalin, digitonin, and digitoxin (digitoxin occur- 
ring in the leaves only). The preparation known as commercial 
digitalin has been shown to consist of mixtures containing more 
than one of these glucosides. 

The process for the preparation of commercial digitalin consists in 
extracting digitalis-leaves {Digitalis, U. S. P.), with alcohol, distil- 
ling off the alcohol, dissolving the residue in water containing a 
small quantity of acetic acid, removing much of the color from the 
solution by means of animal charcoal, neutralizing most of the 
acetic acid with ammonia, precipitating the glucosides by adding 
tannic acid (with which they form insoluble compounds), washing 
the precipitate, rubbing and heating it with alcohol and lead oxide 
(which removes the acid as insoluble lead tannate), again decolori- 
zing by means of animal charcoal, evaporating to dryness, washing 
out with ether any impurities still remaining, and drying the resi- 
due. The product is uncrystallizable and somewhat indefinite. 

Pure digitalin is prepared from commercial digitalin by dis- 
solving the latter in 4 times its weight of 95 percent, alcohol, add- 
ing 5 times its weight of ether, separating the liquid from undis- 
solved matter and evaporating it in vacuo to about two-thirds of 
its volume, adding water, filtering off and washing the precipitated 
crude digitalin, and then recrystallizing this from 95 percent, alco- 
hol. The pure product is colorless and granular, but it can also 
be obtained in needle-shaped crystals. It is sparingly soluble in 
water, ether, and chloroform, but easily soluble in alcohol. When 
moistened with sulphuric acid and exposed to the vapor of bromine, 
a violet color is produced. On hydrolysis digitalin yields digifali- 
genin, C.^^H.^^.^ ; digitalose, C^H^^O,^, and glucose. 

Digitonin, C^Jl^fi^^. — This glucoside, which does not possess 
the physiological action characteristic of digitalis, is closely allied 
to saponin. It yields on hydrolysis digifogenhi, C^H.^^O.,, galac- 
tose, and glucose. 



500 ORG ASIC CHEMISTRY. 

" Dirjif aline crystal/isee." — On treating commercial digitalin 
with chloroform an inert substance remains undissolved. The solu- 
tion yields on evaporation a substance known in France as digi- 
taline crystallisee which is apparently identical with digitoxin ; it 
may be crystallized from alcohol in radiating needles (Xativelle). 
The therapeutic effect of this substance is identical with that of 
the preparations of digitalis, but more constant in its action, and, 
of course, intensely powerful. 

Digitoxin, C.^^H.^Ou, is the highly poisonous glucoside of digi- 
talis leaves. It yields on hydrolysis digitoxigenin, 0^.^.^^0^, and 
digitoxose, CgHj^O^. 

Elaterix, CgoHogO-. — Boil elaterium, the dried sediment from 
the juice of the squirting-cucumber fruit, with chloroform, filter, 
evaporate, wash the precipitated elaterin with ether, recrj^stallize 
it from chloroform and again wash the crystals with ether. The 
product, [Elaterinum, U. S. P.), occurs in small hexagonal plates or 
prisms. 

Elaterin is probably not a true glucoside. It does not always 
respond to the test for glucose after boiling with acids ; and when 
it does, the reaction is possibly due to prop hefin, a glucoside stated 
by Walz to be present in elaterium. 

Elaterin is the active principle of the so-called elaterium. 
Elaterium occurs in light friable greenish-grey cakes. Good 
specimens of this drug should yield not less than 20 percent, of 
elaterin by the above process. 

Test. — Elaterin is placed in a watch-glass with a drop of liquefied 
carbonic acid, and then two drops of concentrated sulphuric acid; 
a carmine color is developed (Lindo). 

Feaxgulix, C^H^gOg, is a glucoside found in the bark of 
Rhamnm frangula {Frangula, U. S. P.). On hydrolysis it yields 
emodin, C^-Hj^Og, and an unfermentable sugar, rhamnose, C^H^g^.. 

Gextiopiceix or Gextiax-bitter, C20H30O12, the neutral crys- 
talline principle of the root of Gentiana lutea (Ge)ifiana,JJ . S. P.). 
It is soluble in water and dilute alcohol. Alkalies decompose it. 
Dilute acids convert it into gentiogenin and glucose. Gentian 
root also contains a variety of tannin and crystalline acid, 
HCj^HgO-, termed gentianic, or gentisic acid, or genti^in. Fused 
potassium hydroxide, etc., give with the latter an acid (C.HgOJ, 
which has also, unfortunately, been called gentisic acid. 

Glycyrehizix or Ghjcyrrhizic Acid, C^^H.^^Og, Gorup-Besanez; 
C^Hp.^XOjg, Habermann. — Licorice-root {Glycyrrhiza, IT. S. P.), 
in addition to uncrystallizable sugar contains 3 or 4 percent, of a 
sweet substance, glycyrrhizin, which, when boiled with hydro- 
chloric acid or dilute sulphuric acid, yields a resinoid bitter sub- 
stance, glycyrrefin, and an uncrystallizable sugar resembling glu- 
cose. Glycyrrhizin is present in Extractum Glycyrrhizcp, U. S. P., 
Fluidextractum Glycyrrhizfc, U.S. P., and in the evaporated decoc- 
tion {Stick Licorice, Spa?iish Licorice, or Solazzi Juice). It is soluble 



GLUCOSIDES. 501 

in ammoniacal water. The tropical substitute for licorice is the root 
of Abrus precaforiiis or Indian Licorice, the kunch or gunj of Bengal, 
the rata of Hindustan, and the jequirity or jaquerity of Brazil, 
which also contains glucose and glycyrrhizin. The seeds yield 
by maceration a substance which acts as a poison when injected 
into the blood, but not when swallowed. Warden and Waddell 
regard the active principle as an albuminoid and term it abri7i. 
Bruylants and Venneman consider it to be a product of germina- 
tion, and call it jequeritin. Bechamp and Dujardin regard the 
latter as a mixture of legumin and jequerity zymase. Glycyrrhizin 
has considerable power of disguising nauseous flavors. Roussin 
refers the sweet taste of licorice not to pure glycyrrhizin but to a 
combination of glycyrrhizin with alkalies, and states that ammo- 
niacal glycyrrhizin has exactly the sweetness of licorice-root. The 
formula of this ammonium glyeyrrhizate is said by Haberraann to 
be (NH^)3C^^HgQN0jg. Sestini finds that the glycyrrhizin of licorice- 
root is chiefly calcium glycyrrhizate. 

GuAiACiN. — Resin of guaiacum {Guaiacum,\S . S. P. ), an exuda- 
tion from the wood of Guaiacum officinale, is probably a mixture 
of several substances, among which are guaiaretic or guaiaretinic 
acid, C.^qH2^0^ (Hlasiwetz), guaiaconic acid, Q^^^f)^, Sind guaiacin, 
a glucoside. On boiling guaiacum resin with dilute sulphuric 
acid for some time, glucose is found in the liquid, a green resinous 
substance (guaiaretin) remaining insoluble (Kosmann). Most 
oxidizing agents, and even atmospheric air, especially under the 
influence of certain organic substances, produce a blue, then 
green, and finally a brown color when brought into contact with 
an alcoholic solution of guaiacum resin. Ferric chloride is the 
official test for this purpose. These effects are said to be due to 
three stages of oxidation (Jonas). They may be observed on 
adding the solution to the inner surface of a paring of a raw potato. 

Helleborin, C^^'iI^^O^., and Helleborein, C^^M^JJ^.^, are crys- 
talline glucosides occurring in the roots of Black Hellebore {Helle- 
borus niger), or Christmas rose, and Green Hellebore {H. viridis), 
ranunculaceous herbs. The former is insoluble in water, but 
soluble in ether; the latter soluble in water, but insoluble in ether. 

Jalapin, q,Hg,O.,,orC,,H,03O2,, and Convolvulin, C3,H5,A,. 
— Some confusion exists regarding the names of these substances. 
The glucoside originally known as jalapin is now almost uniformly 
called convolvulin in Germany, while the German jalapin, which 
appears to be identical with scammonin, is not infrequently called 
convolvulin. According to Kayser and Mayer, jalap-resin con- 
tains two distinct substances — convolvulin, chiefly obtained from 
Mexican male jalap (Ipomcea Orizabensis) , and jalapin, most 
largely contained in the true jalap {Exogonium purga, or Iponuva 
purga); the former is soluble in ether, the latter insoluble. 
Fliickiger advocated the' names jalapurgin for the ether-insoluble 
jalapin and orizabin for convolvulin, soluble in ether, but these 



502 ORGANIC CHEMISTRY. 

names have not been generally adopted. In the U. S. the name 
convolvulin is applied to the ether-insoluble hard resin which is 
the medicinally active constituent of jalap. 

Jalap-resin {Resbia Jalapce, U. S. P.), is obtained by digesting 
and percolating jalap tubercles [Jalapa, U. S. P.), with alcohol, 
distilling off part of the alcohol, pouring the remainder into water, 
and Avashing and drying the precipitated resin. Jalaj) thoroughly 
exhausted by this process should furnish, according to the Phar- 
macopoeia, not less than 8 jjercent. of resin, of which resin not more 
than three-sixteenths should be soluble in ether, a test which 
excludes resin of Tampico jalap and scammony resin, both of 
which are soluble in ether. The tincture of jalap is sometimes 
decolorized by animal charcoal, and the evaporated product sold 
as "jalapin. " 

Jalap-resin is insoluble in oil of turpentine; common resin or 
rosin, soluble. If the presence of the latter is suspected, the 
specimen should be powdered, digested in turpentine, the mixture 
filtered, and the filtrate evaporated; no residue, or not more than 
that yielded by the turpentine itself, should be obtained. 

Tampico Jalap, from Ipomcea simulam, yields a resin which 
apparently is chiefly convoh^^ilin, but sometimes contains jalapin; 
for a sample obtained by Hanbury was entirely soluble in ether, 
and another extracted by Umney was almost wholly soluble, 
while Evans purified some, of which only half Avas soluble. 

The Kaladana resin (Syn. Pharbiiisin) obtained from the dried 
seeds of IpomcEa hederacea (Syn. Pharbitis Nil), is a resin analo- 
gous to, if not identical with, resin of jalap. 

Turpethurn, Turpeth, is dried root and stem of Ipomoea Turpe- 
thum. It contains turpethin, a resinoid glucoside resembling 
jalapin in properties. The word turpeth is in Persian turbid, a 
cathartic, or turbad, a cathartic root. 

LoGANiN, C25H.^^Oj^, is a glucoside obtained from the pulp of 
the fruit and from the seeds of Strychnos Nux-vomica, Loganiaceee 
{Nux Vomica, U. S. P.), by Dunstan and Short. Boiled with 
dilute sulphuric acid, it yields glucose and loganetin. 

OuABAix, C3oH_^gOi2 (Arnaud) ; or C3oH320^_^, is a very poisonous 
glucoside resembling strophanthin, found in the wood of an 
acokanthera and in arrow poisons prepared from this wood. 

PiCRORHizix is a bitter crystalline glucoside existing, to the 
extent of 15 percent., in the dried rhizome of Picrorhiza Kiirroa. 
Boiled with 1 percent, aqueous hydrochloric acid, it yields glucose 
and resinoid picrorhizetin. Picrorhiza is said also to contain 
cathartic acid (Hooper). 

PiCROTOXix is a crystalline bitter poisonous principle {-iKpbc, 
picros, bitter, and toSikov, toxicon, poison) occurring in Cocculus 
Indicus, the dried fruits of J namirta paniculata. Ludwig regarded 
it as a glucoside; but its constitution is not yet satisfactorily ascer- 
tained. Bar+h and Ivretschy state that the so-called picrotoxin 



GLUCOSIDES. 503 

may be separated into picrotoxi?i proper, CjjHj^OgjHgO, which is 
bitter and poisonous; picrotin, C^gH.^jjOjg+wHgO, which is bitter 
but not poisonous; smd anamirtin, C^gHg^O^Q, which is neither bitter 
nor poisonous. Schmidt asserts that the original picrotoxin is 
definite, and has the formula C^oR^fi^^,- but that some solvents 
decompose it into picrotoxinin, C^^H^gOg, which is poisonous, and 
pic7^otin, CjgHjgO^, which is not poisonous. 

POLYCHROITE, see p, 551. 

QuASSii^, CjoHj^C^s' Wiggers; or C^^lrL^^O^, Christensen, obtained 
from Quassia, U. S. P., is said to be a glucoside; but Oliveri and 
Denaro question the statement, and find quassin to have the 
formula CggH^^O^^. 

SALiciNjCjgH^gO^. — This substance {Salicinum, U. S. P.), is 
contained in and easily extracted from the bark of various species 
of willow {Salix) and of Populus. It occurs in white, shining, 
bitter crystals, soluble in 21 parts of water or 71 of alcohol at 
ordinary temperatures. 

Tests. — 1. To a small portion of salicin placed on a white 
plate or dish, add a drop of concentrated sulphuric acid ; a 
deep red color is produced. 

2. Boil salicin with dilute sulphuric acid for some time ; it 
is converted into saligenin or saligenol, C^HgO^, and glucose. 
Test for the latter by the copper test. 



C,,H.,0, + H,0 = C„H.(OH)CH,OH + C,H„0, 

Salicin Water Saligenol Glucose 

3. To another portion of the liquid, carefully neutralized, 
add a ferric salt; a purplish-blue color is sometimes produced, 
due to the reaction of the saligenin and the ferric salt. The 
saligenin is, however, so rapidly decomposed by acids into 
saliretin, C.HgO, and water, that this reaction is almost value- 
less as a test. The saligenin may, however, be obtained by 
the action of synaptase on salicin. 

4. Heat a mixture of about 1 part of salicin, 1 of potassium 
dichromate, Ik of sulphuric acid, and 20 of water in a test- 
tube ; a fragrant characteristic odor is evolved, due to the 
formation of salicylaldehyde, CgH^OH.COH, an essential oil 
identical with that existing in meadow-sweet (Spircea Uhnaria) 
and in heliotrope. 



CgHpH.CH.pH + O -^ C.H^.OH.COH + H.,0 

Saligenol Nascent Salicylaldehyde Wa"ter 



504 ORGANIC CHEMISTRY, 

Santonin, CigHigOg. — This substance is, apparently, the anhy- 
dride or, rather, lactone,^ of a weak acid (Hesse) insoluble in 
ammonia, but forming a soluble calcium salt. Indeed by boiling 
santonin for twelve hours with baryta water, Cannizzaro has 
obtained a salt from which hydrochloric acid separates santo7iic 
acid, C15H20O4. From a solution of calcium santonate the santonin 
is precipitated by acids. Boiled for some time with dilute sul- 
phuric acid, it yields 87 percent, of an insoluble resinous sub- 
stance {santoniretin) and glucose (Kosmann). Santonin {Santoni- 
num, U. S. P.), is official ; it is soluble in an aqueous solution of 
twice its weight of sodium carbonate. Possibly (Berthelot) san- 
tonin resembles carbolic acid, — in other words, is a phenol, 
Ci5Hir,(OH)3. Its glucosidal character is questionable. 

Process. — The process for its preparation consists in boiling 
santonica, (Santonica, U. S. P.), the dried, unexpanded flower- 
heads or capitula oi Artemisia panciflora) with milk of lime (whereby 
calcium santonate is formed), straining, precipitating the san- 
tonin or santonic acid by the addition of hydrochloric acid, wash- 
ing with ammonia water to remove resin, dissolving in alcohol and 
digesting with animal charcoal to get rid of coloring-matter, 
setting the alcoholic solution aside to deposit crystals of santonin, 
and purifying by recrystallization from alcohol (Mialhe). 

Test. — To highly diluted solution of ferric chloride add an 
equal volume of concentrated sulphuric acid. To this reagent 
add the santonin or powder or substance suspected to be san- 
tonin, and cautiously apply heat. A red, purple, and finally 
violet color is produced (Lindo). Santonin added to warm 
alcoholic solution of potassium hydroxide yields a violet-red 
color. 

Saponin, Cg^H.^O^., H^O, is a peculiar glucoside occurring in 
Soapwort, Saponaria[ the root of the common Pink, and many 
other plants ; its solution in water, even though very dilute, froths 
like a solution of soap. Heated with dilute acid it yields glucose 
and sapogenin, Ci^H2202. Pereira considered smilacin [salseparin 
or parallin), one of the principles of the supposed activity of Sarsa- 
parilla (Sarsaparilla, U. S. P.), to be closely allied to, if not 
identical with, saponin. According to Klunge (''Pharmaco- 
graphia"), parallin, by action of acids, yields parigenin. The 
aqueous solutions of parallin froth when shaken. Von Schultz 
states that sarsaparilla contains three homologous glucosides anal- 
ogous to saponin, namely, sarsaparill-saponin, CooHggOio, sarsa- 
saponin, C.gH.^pOio, and parallin, C^^^^O^Q. 

' Certain hydroxy acids, by loss of water, yield lactones. Aromatic com- 
pounds containing NH2 in the ortho position and losing water by the oxi- 
dation aud removal of one or two atoms of that hydrogen furnish bodies 
whicli may be distinguished as lactams riwA lactims. 



GLUCOSIDES. 505 

Saponin is also met within the root of Poly gala Senega {Senega, 
U. S. P.), though the activity of senega is said to be due to two 
ghicosides, senegin and polygalic acid. 

Saponin is readily obtained from the bark of Quillaja saponaria, 
or soap-bark {Quillaja, U. S. P.), by boiling the aqueous extract 
in alcohol and filtering while hot. Flocks of saponin separate on 
cooling. It is a white, non-crystalline, friable powder. 

The alleged toxic properties of commercial saponin are said by 
Kobert to be due to sapotoxin and quillaic acid which seem to be 
identical with senegin and polygalic acid respectively. 

SCAMMONIN, C^^H-gOio, (apparently identical with the substance 
called convolvulin in Britain). — Boil resin of scammony {Resina 
Scammonii, U. S. P.), with dilute sulphuric acid for some time ; 
glucose may then be detected in the liquid, a resinous acid termed 
scammonolic acid, CiJlsoO.^, being produced at the same time. This 
acid is also obtained by the hydrolysis of convolvulin. Accord- 
ing to Kromer, scammonin is oxidized by nitric acid into oxalic, 
valeric, and butyric acids, carbonic anhydride, and an acid melt- 
ing at 101° C, which is isomeric with sebacic acid. Potassium 
permanganate oxidizes scammonin to oxalic and valeric acids, and 
the monobasic scammonolic acid. Kromer gives the formula for 
scammonin as CggHijoO^.^. 

Natural scammony {Scammonium, U. S. P.), is an exudation 
from incisions in the living root of Convolvulus Scammonia. It con- 
tains from 10 to 20 percent, of gum, and, therefore, when tritur- 
ated with water, gives an emulsion. It should yield at least 75 
percent, of resin soluble in ether. The official resin of scammony 
contains no gum, and therefore gives no emulsion when triturated 
with water. 

Resin of Scammony is almost entirely soluble in ether. Spir- 
gatis states that it is identical with the resin of Mexican Male 
Jalap, which also is soluble in ether. Sulphuric acid slowly red- 
dens it. It is said to be liable to adulteration with resin of true 
jalap, guaiacum-resin, and common rosin. Eesin of true jalap is 
insoluble in ether, guaiacum-resin is distinguished by the color- 
tests mentioned under Guaiacin, and rosin is recognized by the 
action of sulphuric acid. 

SciLLAiN. — Schroflf, and, afterwards Riche and Remont, be- 
lieved the bitter principle of the squill-bulb {Scilla, U. S. P.), to be 
a glucoside. Merck has extracted substances which he has termed 
scillipicrin, scillitoxin, and scillin, and to which the bitter taste 
of squill is due. Scillitoxin appears to be identical with the scil- 
lain of V. Jarmerstedt. Schmiedeberg has given the name sinisfrin 
to a squill carbohydrate. Squill contains a large quantity of 
mucilage. 

The bulbous root of Crinum Asiaticum is included in the Pharma- 
copoeia of India, as a substitute for squill. It has not been chemi- 
cally investigated. 



506 ORGANIC CHEMISTRY. 

Strophanthin, [Strophanthinum, U. S. P.), C32H4SO16, Feist ; 
C3iH4sOj2, Arnaud. — According to Fraser, this is the active prin- 
ciple of strophanthus seeds [Strophanthus, U. S. P.), the dried seeds 
of Strophanthus Kombe, and is a glucoside. He obtained it in 
crystals. Acids convert it into glucose and crystalline strop hcm- 
thidin. Phosphomolybdic acid produces in solutions of strophan- 
thin a bright bluish-green color. Feist states that it yields very 
little, if any, glucose on hydrolysis, but gives, in addition to 
strophanthidin, a white crystalline substance of the formula 
O13H24O10, melting at 207° C, and a sugar of unknown composi- 
tion. Kohn and Kulisch have also investigated strophanthin, 
but they are inclined to accept Arnaud' s formula, and to doubt 
the correctness of Fraser's view and the glucosidal nature of 
strophanthin. Helbing states that its aqueous solution yields, 
with a trace of solution of ferric chloride and some concentrated 
sulphuric acid, a reddish-brown precipitate which after an hour 
or two turns green. Sulphuric acid colors strophanthin dark green, 
changing to reddish brown. Possibly strophanthin is only one of 
the active principles of the different species of strophanthus. 
Strophanthus seeds are used in the preparation of Tinctura Stro- 
phanthi, U. S. P. They contain nearly one-third their weight of 
oil. 



QUESTIONS AND EXERCISES. 

Define glucosides, aud mention those of pharmaceuticalinterest. — Con- 
struct an equation ilhistrative of the formation of oil of bitter almonds 
from amygdaliu. — How much pure amygdaliii will yield one grain of 
hydrocyanic acid? — To what does cherry-laurel water owe its activity? 
—Mention the active principle of senna. — State the circumstances under 
which guaiacum-resin yields glucose. — Mention a test forguaiacum-resin. 
— How may the adulteration of jalap-resin by rosin be detected? — Enumer- 
ate the tests for salicin.— How is santonin officially prepared ? — Name 
sources of saponin. — What is the difference between scammony and resin 
of scammony ? — How would j'ou detect resins of turpentine, guaiacum, or 
jalap, in resin of scammony ? 



UNCLASSIFIED MEDICINAL PRINCIPLES, ETC. 

The following articles, employed medicinally in such forms as 
Decoction, Extract, Infusion, Tincture, etc., contain active princi- 
ples which have not yet been thoroughly examined. Some of 
these principles have been isolated, and a few have been obtained 
in the crystalline condition; but their constitution has not been 
sufficiently well made out to admit of the classification of the 
bodies either among alkaloids, glucosides, acids, or other well- 
marked principles. 



UNCLASSIFIED MEDICINAL PRINCIPLES, ETC. 507 



Agropyrum, or Triticwn, U. S. P., 
Couch-grass. 

Androcjrciphis (B. P. Add. 1900), 
Andrographis Caules ei Radix, 
P. I., from Andrographis pani- 
culata, Kariyat, a bitter prin- 
ciple. 

Anthemis, U. S. P. 

Apocynum, U.S. P., Canadian hemp. 

Asdepias Tuberosa. Pleurisy root. 
(Asclepedin.) 

Aurantii cortex. (Hesperidin.) 

Azadirachta Indica, Indian Aza- 
dirach (B. P. Add. 1900); Aza- 
dirachtce Cortex et Folia, P. I., 
from Melia azadirachta, Neem 
or Margosa. (A resin; CgeHgoOn 
Broughton ) 

Bonducellce Semina, P.I., from 
Ccesalpinia ( Guilandina) Bou- 
ducella. Bonduc-seeds or nickar- 
nuts. 

Buchu, U. S. P. 

Buteoe Semina, B. P. Add. 1900. 

Calendula, U. S. P. Marigold 
( Calendulin, Stoltze. ) 

Calotropis, B. P. Add. 1900, and 
P. I., from Calotropis procera and 
C. gigantea. Mudar. 

CanellcE cor te x. (Cascarillin, 
C12H11O4.) 

Caulophullum Thcdictroides. Blue 
cohosh. Alkaloid ? 

Cimicfuga (Actoea) r acemo sa 
(Cimicifugin ; said by Conard 
to be neutral, and by Falck 
alkaloidal). Black cohosh or 
black snake-i'oot. Cimicifuga. 

Cucurbttce Semina Prmparata, melon 
pumpkin seeds, B. P. Add. 1900. 
or Pepo, U. S. P. from Cucur- 
hita maxima, Duch. {Cucurbiia 
Pepo, Linn.). A remedy for 
tape-worm. 

Cypripedium pubescen s Cypri- 
pedin ?) . Ladies' slipper ( Cypri- 
pedium, U. S. P. ) . 

Euonymus airopurpureus. Euony- 
mus, U. S. P. Wahoo-bark. 
(Euonymin?) 

Eupatorium perfoliatum. Thorongh- 
wort or Boneset. Eupatorium, 

u. s. p. 



Gossypii Cortex. Cotton Root 
Bark, U. S. P. 

Gidancha tinospora, B. P. Add. 
1900, the dried stem of Tinos- 
pora cordifolia [Tinosporce Radix 
et Caules, P. L). 

Hamamelis Virginica. Witch- 
hazel. 

The official portions are 
Hamamelidis Cortex, U.S. P., the 
source of Aqua Hamamelidis, 
U. S. P., and Hamamelidis Folia, 
U. S. P., the source of Fluid- 
extracium Hamamelidis, U. S. P. 

Hydrocotyles Folia, P. L, from 
Hydrocotyle Asiatica. Indian 
pennywort. 

Hygrophila (B. P. Add. 1900), the 
dried herb, Hygrophila spinosa. 

Iris versicolor. Blue flag. (Iridin 
or Irisin ?) 

Kava {Kavoe Rhizoma, B. P. Add. 
1900), a remedy in alcoholism. 

Lactuca. (Lactucin, etc.). The 
milk-juice, dried, yields Lactu- 
carium, U. S. P. 

Lappa, U. S. P., Arctium Lappa, 
Lappa officinalis. Burdock 

Lupulus. 

Magnolia. Swamp sassafras, or 
beaver tree. 

Marrubium, U. S. P. Horehound. 
Marrubein, a crystalline bitter 
substance (Mein). 

3Iaticce Folia. Matico U. S. P. 

Phytolacca, U. S. P., Poke root. 
Phytolaccin, a crystalline sub- 
stance (Claassen). 

Scutellaria, U. S. P., Skullcap. 

Soymidce Cortex, P. I., Rohun 
Bark, from Soymida febrifuga. 

Taraxacum, U. S. P., (Taraxacin). 

Toddalia, the dried root-bark of 
Toddalia acideata, B. P. Add. 
1900 ; Toddalice Radix, P. I. 

Triiicwn repens. Rhizome of 
couch-grass. See Agropyrum,ante. 

Veronica Vir gini ca,voots and 
rhizome. Culvers root; Lept- 
andra, U. S. P. (Leptandrin?). 

Viburnum prunifolium, U. S. P., 
Black haw. Viburnum opulus, 
U.S.P. Cramp-bark. ( Vibuniin). 



508 ORGANIC CHEMISTRY. 

ALKALOIDS. 

Constitution of Alkaloids, or Organic 

Natural Alkaloids.— The natural organic bases, alkaloids, or 
alkali-like bodies {euhg, eidos, likeness), have certain analogies 
with ammonia. The constitution of some of them is compara- 
tively simple, while in many cases it is exceedingly complex and 
has not as yet been fully elucidated. All contain nitrogen, and 
may be regarded as ammonia which has had its hydrogen replaced 
wholly or in part by one or more organic groups of greater or less 
complexity. Some of the more important alkaloids are closely 
related to pyridine, quinoline, etc., compounds which are referred 
to further on. 

Numerous artificial organic bases, having a very simple relation 
to ammonia, have already been formed. These are commonly 
called amines, and they are primary, secondary, or tertiary accord- 
ing as one, two, or three atoms of hydrogen in ammonia have 
been replaced by radicals, as seen in the following general formulae 
(R=any univalent radical): — • 

E) E| E) 

H In e In e In; 

h] h] e] 

or in the following examples : — 



H N C,H, N C,H, N 

H J H ] C,H, 

Ethylamine Diethylamine Triethylamine 

The primary and secondary amines are sometimes called amino- 
bases and imino-bases respectively. 

Formation of some of the Artificial Organic Bases. — A few illus- 
trations will suffice. Just as the addition of hydrogen iodide, HI, 
to ammonia, NH3, gives ammonium iodide, NH^I, so the addition 
of ethyl iodide, C^H.I or EtI {see p. 398), to ammonia gives ethyl- 
ammonium iodide, NHgC^H.I or NH^Etl. A fixed alkali liberates 
ammonia from ammonium iodide ; it liberates ethyl-ammonia 
or ethylamine, NH^Et, from ethyl-ammonium iodide. Ethyl- 
amine with ethyl iodide, EtI, gives diethyl-ammonium iodide, 
NH.^(C2lI.)J or NH^EtJ. From the latter potassium hydroxide 
liberates diethyl ammonia or diethylamine, NHEt.,. Diethylamine 
with ethyl iodide gives triethyl-ammonium iodide, NH(C2H.),J 
or NHEt.J. The latter with caustic alkali gives triethyl-ammonia 
or triethylamine, NEt.,, and this with ethyl iodide gives tetrethyl- ■ 
ammonium iodide, N( C.,II.)^I or NEt J, which is not decompos- 
able by potassium hydroxide. 

What has just been stated respecting ethyl iodide is true of a 
number of other organic iodides, so that a large number of artificial 
organic bases and their salts can be produced. The reactions are 



II 



ALKALOIDS. 



509 



not always so sharp, however, as might be inferred from the pre- 
ceding paragraph, mixtures of primary, secondary, and tertiary 
compounds, rather than a single amine, being obtained. Some 
of these artificial bases not only resemble natural alkaloids, but 
yield solutions which are strongly caustic liquids, like ammonia 
water. 

The radicals in the amines which take the place of the hydrogen 
in ammonia are not necessarily all of one kind as in the case of 
the ethyl derivatives referred to above, but two or more different 
radicals may be present in the same amine. Thus, for example, 
we have methyl-ethyl-amylamine, CgH^^N, or ^ CB.fi ^H^C^hL^^, 
or NMeEtAy, a colorless, oily substance, of agreeable aromatic 
odor, while such substances as methyl-ethyl-propyl-isobutyl-am- 
monium chloride, NCHgCgH^CgH^C^HgCl, have also been prepared. 

Analogues of Amines^ — As might be expected from the analogy 
of phosphorus, arsenic, and antimony with nitrogen, there are 
also known phosphines, arsines, and stlbines ; bases resembling 
amines, but containing the respective elements (P,As,Sb) in place 
of the nitrogen of the amines. 

Methylamine, CH^NHg, and trimethylamine, {CH^.^, have been 
obtained both artificially and from naturally occurring organic 
materials. Methylamine was found by Schmidt, in Mercurialis 
annua and M. perennis, and previously by Eeichardt, who termed 
it mercurialine. Trimethylamine is produced in large quantities in 
the dry distillation of the evaporated residue of the spent wash 
produced in beetroot spirit distilleries. 

Propylamine, CgH^NHg, is a volatile oil, one product of the 
destructive distillation of bones and other animal matters. 

Besides the amines derived from a single molecule of ammonia, 
which are called monamines, there are also diamines, triamiiies, 
etc. , which may be looked upon as derivatives of two, three, etc. , 
molecules of ammonia. Thus ethylene-diamine is represented by 
the formula C2H^(NH2)2. Diethylene-diamine, NH(C2Hj)2NH, 
is used medicinally under the name piperazifie ; its constitution 
resembles that of piperidine {see p. 538), but with the group NH 
taking the place of a CH^ group in that compound. 

Hydroxylamine. — Besides the various amines already mentioned, 
ammonia may have one atom of its hydrogen displaced by 
hydroxyl, hydroxylamine, NH^OH, resulting. Hydroxylamine 
is formed by the reduction of the nitric acid, when zinc, dilute 
sulphuric acid, and a little nitric acid interact. It yields substi- 
tution products, as ethylhydroxylamine, NHCjH^OH, and addi- 
' tion compounds, as hydroxylamine hydrochloride, NH.30H,HC1: — 



(H 


(H 


(C,H, 


N ^ H HCl 

(oh 


nJ h 


N^ H 


N H 


1h 


(oh 


1 OH 


Ammonia 


Hydroxylamine 


Ethyl- 


Hydroxylamine 






hydroxylamine 


hydrochloride 



510 ORGANIC CHEMISTRY. 

Hydroxylamine and aldehydes yield aldoximes. Hydroxyl- 
amine and ketones, such as acetone, yield acetoximes. [See Man- 
uals, not limited to the requirements of medical and pharmaceu- 
tical students.) 

Hydrazine, HgN — NHg. Diethylamine, by action of nitrous 
acid, yields a nitroso-derivative which, on reduction, furnishes 
what apparently is a diamidic compound — diethyl-hydrazine, 
(C2H5)2N — NHj. Hydrous hydrazine has the formula H^N — 
NH2,H20. Hydrazine itself cannot very easily be isolated. Its 
salts with ordinary acids are generally crystalline, and isomorphous 
with corresponding ammonium salts. Acidulated, they have very 
powerful reducing properties, and act as strong poisons toward 
the lower organisms. Phenylhydrazine, CgH^HN — NHg, is an 
extremely useful agent ; employed in making antipyrine, various 
coloring-matters, etc. It forms important compounds with the 
sugars. 

Azoimide or imidazoic acid, HNg, is a substance closely resem- 
bling the haloid acids, and was originally prepared by Curtius 
from hydrazine and ethyl hippurate ; it may, however, be prepared 
more easily by a method proposed by Wislicenus, in which soda- 
mide, NaNHg, j^repared by passing ammonia over melted sodium, 
is heated with nitrous oxide. 

Plant Alkaloids. — These are of great importance to the medical 
and pharmaceutical student. They are treated in considerable 
detail in the succeeding pages. 

Animal Alkaloids. — Many well-known alkaloids occur in the 
juice of the flesh, and in other parts of animals. Ordinary extract 
of meat contains abundance of crystals of creatine, C^HgN302, and 
some creatinine, C^H.NgO. Creatine easily parts with the elements 
of water and yields creatinine ; it takes up the elements of water 
and yields sarkosine, C3H-NO2, and urea, CH^N20. Sarkosine is 
methyl-glycocoll. Taurine, C2H.NSO3, may l3e obtained from 
bile ; and it can be constructed artificially from its elements. 
Some animal tissues, as of the spleen, brain, and pancreas, yield, 
as a product of work, leucine, C^H^^NOg, which occurs in white, 
j)early crystals ; also tyrosine, CgHj^NO.^. Lecithin, which occurs 
in yolk of egg and in the brain, is a highly complex choline 
derivative, being a distearic glycerophosphoric choline ester, 

As examples of some other animal alkaloids, Gautier has 
obtained several new alkaloids from albuminoids, and hence has 
termed them leucomaines {/evuojpa, leucoma, white of egg), namely, 
xaiithocreatinine C-H^^N^O, crusocreatinine, C.HgN^O, amphicrea- 
tinine, CgHjglST.O^, Rnd psendoxanthine, C^H.N.O. The leucomaines 
and the animal alkaloids generally are of great physiological 
interest. Some of the leucomaines are toxic and indistinguishable 
from ptomaines ; in fact, the three classes merge into one another. 



ALKALOIDS. 



511 



Ptomaines. — A series of diamines, many of them toxic, have 
been isolated, by Brieger, from decaying nitrogenous animal prin- 
ciples, including the putrid albuminoids or proteids of the human 
body itself — hence the name jo^omames {itTuiia, ptoma, a corpse). 
These have some medico-legal importance, but, inasmuch as they 
may occur in the living body, poisoning the blood during the 
progress of disease, especially disease associated with the develop- 
ment of micro-organisms or microbes, that is, zymotic disease 
{^vfirj, zume, leaven or ferment), they have great pathological 
interest — indeed, physiological interest also, for one of a curari- 
like character seems to play a part in the process of digestion. 
The names of some of these bases are neurine, CgHjgNO, and 
neuridine, C^H,,N„, from putrid ^esh ; muscarine, C^^H^.^NO.^, and 



cadaverine, C^H^gN, 



gadinine, Q^H^^O^, from putrid fish 

perine, and putrescine, Q>J^^^,^, from putrid human remains, 
choline being met with in the earlier stages of decay ; and tetanine, 
Cy^^^^O^, (the administration of which to animals produced 
symptoms resembling those of tetanus in man), from beef putrefied 
by the agency of the microbe which is associated with the cause 
of traumatic tetanus, so distressing to the human subject. Tyro- 
toxicon was the name given by Vaughan to a toxic ptomaine he 
isolated from poisonous cheese {rvpog, turos, cheese ; to^lkov, toxicon, 
poison), afterward from poisonous milk and cream, which, taken 
as food, had caused more or less vomiting, headache, and diarrhoea. 
Brieger states that when shell-fish is poisonous this is due to the 
presence of a ptomaine he has named mytiloxine, CpH^jNOg. 
Para- and meta-phenylene-diamine appear to have all the char- 
acters of leucomaines or ptomaines, the latter causing intense 
influenza. 

Alkaloid of both Plant and Animal Origin. — Choline, C^H^gNOg, 
occurs in the bile and the brain, also in ergot and ipecacuanha, 
hops, areca nut, cotton-seed cake, Scopola .Japonica, etc. Guanine, 
C5H5N5O, and sarkine, CjH^N^O, are found in flesh and in young 
plant leaves. Fresh meat furnishes carnine, C^HgN^O.^, which 
also occurs in yeast ; and betaine, C^H^^NOg, is found in beetroot, 
cotton-seed cake, and in urine. 

Attempts to form artificially the more important natural organic 
bases commonly used in medicine have for the most part failed, 
although a few alkaloids, identical with the natural substances, 
have been obtained synthetically {e. g., atropine and conine). 
Many artificial colorific alkaloids of the amido-benzene (aniline or 
phenylamine) type, and of a curious double nitrogen type [diazo- 
benzene= CgHj,.N:N.OH) have been obtained. But the type of 
the natural medicinal alkaloids seems to be more closely related 
to pyridine, C^H^N, and to quinoline or chinoline, Cj,H.N. Pyridine 
is producible in various ways, but is contained in bone-oil (from 
the distillation of bones — whence, also, pyrrol, C^H,^N, and thence 
iodopyrrol, or iodol, CJ^HN [lodoluni, U. S. P., a rival of iodo- 



612 



OR GANIC CHEMISTR Y. 



form), together with the homologues picoUne, C^H^N (or methyl- 



pyridine, ortho-, meta 
etc. ; forming 






or para-) ; lutidine, C^HgN ; collidine, 
an homologous series o^ pyridine 



H 
C 



N 



CgHg or HC 



C.NH„ 



HC CH 



N 

^\ 
HC CH 

1 II 
HC CH 



C C 

H 11 

Phenylamiue or auiido-beuzcuc Pyridiue 

From quinine, cinchonine, and strychnine, by the disruptive 
action of caustic alkalies, not only pyridine and homologues, but 
also quinoline have been obtained. Quinoline can be made in 
various other ways, especially (Skraup) from nitrobenzene, aniline, 
and glycerin. Quinoline is closely related both to benzene and 
to pyridine {see the following formula). Its relation to naphtha- 
lene (two carbon-conjoined benzene residues) is similar to that of 
pyridine to benzene. 



HC 

I 
HC 



H 

C 

-"\ 
C CH 



N 



(^ 



CH 



HC 

I 
HC 



C 



CH 

I 



/ 



Naphthalene 



CH 

c c 

a a H H 

Alpha and beta positions Quinoline 

Both pyridine and quinoline. form additive compounds w^ith 
hydrogen {see Piperidine, p. 538). 

By adding six atoms of hydrogen to pyridine, piperidine is 
obtained; and conine, the alkaloid of hemlock, is piperidine with 
propyl (C^H.) replacing one of the hydrogen atoms. It has been 
formed artificially by Ladenburg from picoline {see also ecgonine, 
tropine, etc.). 

Chemists, in the hope, doubtless, of discovering how to produce 
the valuable medicinal alkaloids artificially, have prepared a 
number of alkaloidal derivatives of quinoline. One of them, 
kairine, somewhat resembles quinine. 

It seems reasonable to su])pose that the study of the constitution 
of the alkaloids, in light of the products resulting from the A^ari- 
ous decompositions which they undergo, will in time lead chemists 
to the successful synthesis of, at least, some of the most important 



ALKALOIDS. 



51;] 



alkaloids. Indeed, the rapid progress of investigation and t 
consequent extension of our knowledge of this department of 
chemistry, justify the inference that we are at last almost "within 
measurable distance ' ' of the artificial production of most of the 
natural alkaloids. This is a subject of financial and general com- 
mercial weight; of considerable technological, including phar- 
maceutical, importance; of very great medical consequence, 
especially taken in connection with its ramifications; and of tran- 
scendent scientific interest as illustrating the working of nature's 
forces within the molecules of matter. 

Note on Nomenclature of Natural Alkaloids. — The first syllables 
of the names of the natural alkaloids frequently recall the name 
of the plant from which they are obtained, or some characteristic 
property, while the final syllable is either ine or ia. The com- 
pilers of the United States, British, French, and German Phar- 
macopoeias have uniformly adopted the termination ine. The 
names of the salts of the alkaloids are given on the assumption 
that the acid simply unites with the alkaloid without the elimina- 
tion of water. Thus morphine hydrochloride (sometimes termed 
" hydrochlorate ") is regarded as morphine which has united with 
hydrochloric acid. Acids in general unite with alkaloids and 
form additive salts of a similar kind. 

Antidotes. — In cases of poisoning by alkaloids, emetics and the 
stomach-pump must be relied on rather than chemical agents. 
But astringent liquids may be administered, for tannic acid pre- 
cipitates many of the alkaloids from their aqueous solution, 
absorption of the poison possibly being thus retarded. 

MORPHINE AND OTHER OPIUM ALKALOIDS. 
Morphine. 

Occurrence. — Morphine or morphia, C^^H^gNOg, HgO, occurs in 
opium (the inspissated juice of^ the seed-capsule of the White 
Poppy, Papaver somniferum) perhaps partly as morphine meconate 
[(C^.H^gNOg),,, C,H,0„ SH^O; Dott] and sulphate. The dried 
poppy-capsule contains opium principles, but they vary much in 
nature and proportion: the presence of morphine, narcotine, and 
meconic acid has been demonstrated; also (by Groves) of codeine 
and narceine. Ordinary Asia-Minor opium (Turkey, Smyrna, or 
Constantinople opium) contains, when dried, from 10 to 15 per- 
cent, of morphine. The Pharmacopceia directs that opium used 
for officially recognized purposes, other than the manufacture 
of alkaloids, or of extract of opium of official strength, must con- 
tain not less than 9 percent, of morphine, when the opium is 
quantitatively analyzed [see p. 794) by the official method. 

Morphirie Hydrochloride. — The hydrochloride, Cj^H,<,NO;„ 
HC1,3H,^0 {Morphinoi Hydrochloridum, U.S. P.), occurs in slender 
white acicular crystals; it is prepared by simply decomposing an 
33 



514 ORGANIC CHEMISTRY. 

aqueous infusion of opium with calcium chloride, calcium meco- 
nate and morphine hydrochloride being produced. (If the infu- 
sion, which is always acid, be first nearly neutralized by the 
cautious addition of small quantities of a very dilute ammonia 
water, the calcium chloride then at once causes precipitation of 
calcium_ meconate, which can be filtered oif, leaving a colored 
soTution oT"mor'phine hydrochloride. On the large scale the 
details are somewhat difierent. ) The filtered liquid is evaporated, 
and the impure morphine hydrochloride which crystallizes out on 
cooling is redissolved in water and treated with animal charcoal; 
the morphine is then precipitated from the still colored liquid by 
addition of excess of ammonia, separated by filtration, and dis- 
solved in hot dilute hydrochloric acid; morphine hydrochloride 
separates out on cooling. 

Morphine hydrochloride deposited from a hot solution in about 
twenty times its weight of alcohol is anhydrous. 

Morphine Acetate and Tartrate. — Morphine acetate, Ci^H^gNOg, 
CgH^Og, SH^O {Morphince. Acetas, U. S. P.), is prepared by dis- 
solving morphine (MjrpAmcR, U. S. P.), in acetic acid. Morphine 
tartrate, (Ci^H^9N03)2, C^H^O^, SH^O may be prepared by neutral- 
izing a mixture of morphine and water with tartaric acid. 

Morphine hydrochloride, acetate, and tartrate are soluble in 
water, but the solutions are not stable unless acidulated and con- 
taining alcohol. Even solid morphine acetate is unstable, slowly 
decomposing into acetic acid and morphine ; hence the acid odor 
of morphine acetate; hence, too, the necessity, when a solution 
of morphine acetate of perfectly definite concentration is required, 
of preparing it from a weighed quantity of hydrochloride, or 
of pure crystalline morphine. 

Morphine Sulphate, (Cj.Hj.NO^)^, H,SO„ tU ft {MorpMnce Sul- 
phas, U. S. P. ), is prepared by neutralizing precipitated morphine 
with dilute sulphuric acid. It occurs in white silky crystals, 
soluble in water. 

Analytical ReaMions. 

1. To a minute fragment of a morphine salt add one drop 
of water and warm the mixture until the salt dissolves, then 
stir the liquid with a glass rod moistened with concentrated 
neufra/ solution of ferric chloride; a dirty-blue color is pro- 
duced. 

Even in dilute solutions morphine reduces potassium ferri- 
cyanide to ferrocyanide, hence may be detected by the blue 
precipitate (Prussian blue) produced on the addition of ferric 
chloride and ferricyanide. Other substances, but no other 
official alkaloids, give this reaction. 



ALKALOIDS. 



515 



2. To a drop or two of a concentrated solution of a mor- 
phine salt in a test-tube add a minute fragment of iodic acid, 
(HIO3, p. 280); iodine is set free. Into the upper part of the 
tube introduce a glass rod moistened with mucilage of starch, 
-and warm the solution; dark-blue "iodide of starch" is pro- 
duced. If the mixture of morphine and iodic acid be shaken 
up with chloroform or carbon bisulphide, a violet solution is 
obtained. This reaction is only confirmatory of others, as 
albuminous matters also reduce iodic acid. 

3. To a few drops of an aqueous infusion of opium add a 
drop of neutral solution of ferric chloride ; a red solution of 
ferric meconate is produced. Add solution of corrosive sub- 
limate ; the color is not destroyed (as it is in the case of ferric 
thiocyanate, a salt of similar tint). In cases of poisoning by 
a preparation of opium, this test is almost as conclusive as a 
direct reaction of morphine (the poison itself), meconic acid 
being obtainable from opium only. 

4. According to Lamal, morphine solutions give, on addi- 
tion of uranium acetate, a reddish-brown color, which disap- 
pears on adding acids, while, on adding caustic alkalies a deep 
red precipitate is formed, which turns yellow on adding an 
excess of the reagent. The test is best made by putting 2. to 
10 drops of the morphine solution into a porcelain dish and 
adding the same quantity of uranium solution (0.015 gramme 
of uranium acetate and 0.01 gramme of sodium acetate in 5 
Cc. of water). After evaporating on the water-bath, concen- 
tric, bright red or hyacinth-red spots are left. The reaction 
is still visible with 0.05 milligramme of the alkaloid. Most 
of the other alkaloids give no reaction ; salicylic acid gives 
brick-red spots ; tannin, gallic acid, and pyrogallol brown 
spots. Phenol gives a brown color, slowly disappearing on 
warming. The coloration with uranium acetate is very per- 
manent. 

Other Reactions. — Add sodium carbonate to a solution of 
a morphine salt ; a white precipitate of morphine is produced 
slowly, and is of a crystalline character if the solution is di- 
lute. Collect this precipitate and moisten it with neutral solu- 
tion of ferric chloride ; the bluish tint above referred to is 
produced. — Add an alkali to a solution of morphine hydro- 
chloride, acetate, or tartrate; morphine is precipitated, soluble 
in excess of fixed alkali, far less readily so in ammonia. — 
Moisten a particle of a morphine salt with nitric acid ; an 
orange-red coloration is produced. Warn\ some morphine 



516 ORGANIC CHEMISTRY. 

with concentrated sulphuric acid and sodium arsenate ; a blue- 
green tinge results. — To morphine add concentrated sulphuric 
acid, mix, and add powdered bismuth nitrate to the fluid ; the 
mixture turns dark brown or black. — Heat morphine on plat- 
inum foil ; it burns away entirely. 

Codeine. 

Codeine, or Codeia, C^gHg^NOg, HgO, methyl-morphine, is an- 
other officially recognized opium alkaloid (Codeina U. S. P.). It 
dissolves in the slight excess of ammonia employed for precipita- 
ting morphine in the foregoing process for the preparation of 
morphine hydrochloride. It is obtained by evaporating the am- 
moniacal filtrate, treating the residue with water, precipitating 
with potassium hydroxide, and purifying the precipitated alkaloid 
by recrystallization from ether. Codeine may also be obtained by 
heating a sodium compound of morphine, Cj^H^igNaNOg, with 
methyl iodide, CH^I; sodium iodide and methyl-morphine or 
codeine result. It occurs in white trimetric crystals, soluble in 
88 parts of water or ammonia water, readily soluble in alcohol, 
in chloroform, and in diluted acids. It is soluble in 12.5 
parts of ether. The aqueous solution has a bitter taste and an 
alkaline reaction. The alkaloid dissolves in an excess of sul- 
phuric acid, forming a colorless solution, a small quantity of 
wTiich, when gently warmed on a water-bath with 2 drops of 
solution of ammonium molybdate, or with a trace of ferric chlo- 
ride or potassium ferri cyanide, develops a blue or bluish-black 
color, which, on the addition of a minute trace of dilute nitric 
acid, changes to a bright scarlet, becoming orange. Heated to 
redness in air, it yields no ash. It reduces a solution of one part 
of ammonium selenite in twenty of concentrated sulphuric acid, 
yielding a green color (Lafon). Codeine neither gives a blue 
color Avith ferric chloride nor a red with nitric acid. Both codeine 
and morphine when heated with a mixture of concentrated sul- 
phuric acid and sodium arsenate give a blue color, the morphine 
yielding a greenish blue and the codeine a violet blue. 

Codeine Sulphate, (CigH,jN03)2H,SO„ SH.O, [Codcince, Sul- 
phas, U. S. P.), and Codeine Phosphate CisH^iNOgHgPO,, 2}1,0 
[Codeince Fhosphas, U. S. P.), are official. 

Diotiin, is ethylmorj^hine hydrochloride; CjgHjgNOg, 
HCbHp. 

Heroin is diacetylmorphine, Cj7H^^NO(C2H302)2. Both the base 
itself and its hydrochloride are used in medicine. 

Apomorphine, C^^Hj^NOg 

The alkaloid apomorphine (otto, apo, from, and morphine) was 
obtained from morphine by Matthiessen and Wright. It produces 



ALKALOIDS. 517 

remarkable physiological effects; one-tenth of a grain (in aqueous 
solution) injected under the skin, or a quarter of a grain taken 
into the stomach, produces vomiting in from four to ten minutes. 

Preparation. — Morphine hydrochloride or codeine hydrochloride 
is hermetically sealed in a thick tube with considerable excess of 
hydrochloric acid, and heated to nearly 300° F. (148.8° C.) for 
two or three hours. The product is purified by diluting the con- 
tents of the tube with water, precipitating with sodium bicarbo- 
nate, and treating the precipitate with ether or chloroform. On 
shaking up the ethereal or chloroform solution with a very small 
quantity of concentrated hydrochloric acid, the sides of the vessel 
become covered with crystals of the hydrochloride of the new 
base {Apomorphince Hydrochloridum, U. S. P. ). These may be 
drained from the mother-liquor, washed with a little cold water, 
in which the salt is sparingly soluble, recrystallized from hot water, 
and dried on bibulous paper or over sulphuric acid. The formula, 
Cj^H^^NO^,HCl, may be derived from that of morphine by ab- 
straction of the elements of water. With solution of apomor- 
phine hydrochloride, sodium bicarbonate produces a precipitate 
which becomes green on standing and then forms a solution which 
is purple with ether, violet with chloroform, and bluish-green 
with alcohol. With dilute test-solution of ferric chloride it gives 
a deep red, and with nitric acid a blood-red coloration. 

Other alkaloids exist in opium. In the preparation of 
morphine a considerable quantity of narcotine, CggH^gNO^, or 
CjgHj^(OCH3)3N04, an alkaloid of very weak basic properties, 
remains in the exhausted opium, and may be extracted by 
digesting in acetic acid, filtering, and precipitating by adding am- 
monia. It crystallizes in brilliant needles from alcohol or ether. 
The formula of its hydrochloride is C,2H23NO„HCl,Hp. By ox- 
idation it yields cotarnine and an acid termed opianic. From the 
mother-liquors there have also been obtained thebaine, C,9H2iN03, 
papaverine, (G.^H^jNO^, Hesse; C^oH^.NO^, Merck), narceine, 
CssHy^NOg, cryptopine, Q^^11^.^0^, meconin, C.^JI.^O,, meco7i- 
olsin, CgHioO^, laudanine, C.^H^gNO^, codamine, C^oH^gNO^, 
gnoscopine, C22H23NO7, pseudomorphine, C^^B.^J^fi^, protopine, 
C^oHj^NOg, laudanosine, C.^JI^^]<iO^, hydrocotarnine, C^gH^-NOs, 
rhceadine, O^^Ji^^NO^, meconidine, Q.^Jl^.^0^, lanfhopine, 

A little acetic acid also exists in opium (D. Brown). 

Constitution of Morphine. — Theopium alkaloids, like the cinchona 
alkaloids, have been attacked by many chemists in the hope that 
analytical or, in a sense, destructive investigation would lead to 
synthetical or constructive operations ; and many interesting and 
promising results have been obtained. It is found that morphine 
is a tertiary base; it yields pyridine in several reactions, support- 
ing the view that it is a pyridine derivative. By suitable oxi- 
dation, it yields picric acid, and by fusion with 'caustic alkali, 



518 ORGANIC CHEMISTRY. 

protocatecliuic acid, both which reactions indicate relationship 
to benzene. The nitrogen atom in morphine appears to have a 
methyl group attached to it. But the subject is not yet suffi- 
ciently developed for useful study by ordinary students of medi- 
cine or pharmacy. 



QUESTIONS AND EXEECISES. 

Write some general formulse of artificial alkaloids. — Name the substan- 
ces represented by the following formulae : — 

C3H7) C3H7) CH:0 CH3") CH3) CH3I 

H \ N, C3H7 [ N, C2H5 y N, H ^ N, CH3 } N, CH3 [ N 

Hj hJ C5H11) hJ hJ CH3J 

Describe the treatment in cases of poisoning by alkaloids. — Give a process 
for the preparation of morphine hydrochloride. In what form does mor- 
phine occur in oivlum? — How is morphine acetate prepared ? — What plan 
is adopted for preventing the decomposition of the official morphine solu- 
tions? — Mention the analytical reactions of morphine. — In addition to the 
reactions of morphine, what test may be employed in searching for opium 
in a liquid or semi-fluid material ? — Describe the relation of morphine 
to codeine. — How is apomorphine prepared and what are its properties ? 



QUININE AND OTHER CINCHONA ALKALOIDS. 
Quinine; C,„H,,NA, 3H,0 

Source. — Quinine {Quinina, U. S. P.), and other alkaloids exist 
in the bark of various species of Cinchona {Cinchona. U. S. P. 
and Cinchona Rubra, U. S. P.), and Eemijia Jcinates, or rather, 
quinates.^ 

Extraction of the Mixed Alkaloids. — Mix two ounces of 
powdered cinchona with a quarter of its weight of slaked lime 
and a little water, and extract with a mixture of one part by 
volume of amyl alcohol with three of benzol. Shake the 
liquid product in a separating funnel with an ounce of water 
acidulated with sulphuric or hydrochloric acid. Draw off the 
aqueous liquid, which contains the alkaloids as acid salts, and 
add to it a slightexcess of ammonia. Collect the precipitated 
alkaloids on a filter, wash, and dry by exposure to air, or in 
a desiccator over sulphuric acid. For the separation and 

^Quinic Acid, C7H12O6, occurs in cinchona, cofiee, holly, ivy, oak, elm, 

etc. Heated it yields hijdroquinone, C6H4(OH)2. Oxidized it gives quin- 

one, C6H4O2, which is probably a di-ketone, C4H4(CO)2 

CO 
orC2H2<;p,Q>C2H2. The homologues of benzene yield other "quinoues." 



ALKALOIDS. 519 

assay of the cinchona alkaloids, operations which should not 
be attempted at this stage of study, the advanced student 
should consult the directions given in the U. S. P. 

Quinine Sulphate (Quinince Sulphas, U. S. P.), may be prepared 
by treating cinchona with dilute hydrochloric acid, precipitating 
the resulting solution of quinine hydrochloride by means of sodium 
hydroxide, and redissolving the precipitated quinine in the proper 
quantity of hot dilute sulphuric acid. Quinine sulphate crystal- 
lizes out on cooling in silky acicular crystals, having the formula 
(C2oH2^N^02)2H2SO^, 7H2O. In dry air it loses, by efflorescence, 
five-sevenths of its water. 

Quinine sulphate, the ordinary or so-called neutral sulphate, is 
only slightly soluble in water; on the addition of dilute sulphuric 
acid Quinine Bisulphate, C2oH2^N202,H2SO^,7H20 {Quiniiice Bisul- 
phas, U. S. P.), is formed, which is freely soluble. The latter 
salt may be obtained in large rectangular prisms. A soluble acid 
sulphate having the formula C20H24N2O2, 2H2SO^, THyO, also 
exists. Quinine sulphate is much more soluble in alcohol or alco- 
holic liquids than in water. 

Quinine Hydrochloride (Quinince Hydrochloridurn, U. S. P.), 
may be prepared by neutralizing quinine with hydrochloric acid. 
Its formula is C2oH2,N202, HCl, 2H2O. It is soluble in about 18 
parts of water at 25° C., the sulphate requiring 720. The two 
salts resemble each other in appearance, but the crystals of the 
hydrochloride are commonly somewhat larger than those of the 
sulphate. 

The remaining official preparations of quinine are the hydro- 
bromide, C2oH2^N202lIBr,H20. (Quinince IIydrobromidum,JJ .S.'P.), 
the oleate (Oleatum Quinino'), the salicylate, (C2oH2^N202, 0^11^0.^)2 
H2O, [Quinince Salicylas, U. S. P.), and the scale compounds 
already mentioned (pp. 158, 160). 

Reactions. 

1. To an acidulated solution of a quinine salt add fresh 
bromine-water, shake, and then add ammonia water ; a green 
coloration (thalleioquin) is produced. Chlorine-water, or solu- 
tion of chlorinated lime may be used instead of brt)mine- 
water. 

2. Repeat the foregoing reaction, but prior to the addition 
of ammonia water add solution of potassium ferrocyanide ; 
an evanescent red coloration is produced (Livonius and 
Vogel). 

3. To an aqueous solution of a soluble quinine salt add solu- 
tion of ammonium oxalate ; a white crystalline precipitate of 
quinine oxalate, soluble in acids, is produced. If the solution 



I 



620 ORGANIC CHEMISTRY, 

to be tested be made from ordinary quinine sulphate, excess 
of the hitter should be added to water very faintly acidulated 
with sulphuric acid, and the undissolved crystals removed by 
filtration. 

4. A saturated aqueous solution of any neutral quinine salt 
is made by dissolving so much of the salt in hot water that 
some shall separate when the mixture has cooled to about 
60° F. (15.5° C). After standing for some time, filter. To 
the filtrate, ether wdiich has been washed with water is added 
until a distinct layer of ether remains undissolved, and then 
ammonia in slight excess. After agitation and rest for fifteen 
minutes, all precipitated quinine wdll have redissolved. 

Note. — In the case of quinidine salts well-defined crystals appear 
at the junction of the aqueous and ethereal layers, especially after 
standing. In the case of cinchonidine salts a thick layer of small 
crystals appears at once. In the case of cmchonine salts the undis- 
solved alkaloid makes the ethereal layer nearly solid. In testing 
quinine for other alkaloids evaporate the aqueous solution to one- 
fifth. 

. 5. Formation of Quinine lodo-sulphate. Dissolve quinine 
sulphate in dilute alcohol slightly acidulated with sulphuric 
acid, and add an alcoholic solution of iodine ; a black precipi- 
tate forms. Allow the precipitate to settle, pour away the 
liquid, wash once or twice with cold alcohol and then boil with 
alcohol ; on cooling minute crystals separate. This iodo-sul- 
phate is sometimes termed Herapathite, from the name of one 
of the chemists who discovered it in 1852. The use of 
plates of this substance instead of tourmaline in certain forms 
of polarizing apparatus has been suggested, as they behave as 
tourmaline does toward light passing through them. Under 
the name of " iodide of hydriodate of quinine," Bouchardat 
described and used it in 1845. It is so slightly soluble in 
alcohol that by its means quinine can be fairly well separated 
from its admixture with the other cinchona alkaloids. Accord- 
ing to Jorgensen it has the formula 4C.„H.,,N.,0„3H,SO,, 

2HI,I,.THP. -0 24 _ 2 .4 

6. Prepare a saturated solution of ordinary quinine sulphate 
in water at about 60° F. (15.5° C), and add to 5 volumes of 
that solution 7 volumes of ammonia water (sp. gr. 0.96). 
The alkaloid which is at first precipitated redissolves upon 
slight agitation if the quinine sulphate is free from anything 
but traces of other cinchona alkaloids. If, however, more than 



ALKALOIDS. 



521 



traces of qiiinidine, cinchonidiue, aod cinchonine salts be pres- 
ent, a periiianeut precipitate remains. This is Kerner's 
method of testing quinine sulphate for other cinchona alka- 
loids. It turns upon the fact that the solubility of the cin- 
chona alkaloid sulphates in water is in the opposite order to 
the solubility of the alkaloids themselves in solution of am- 
monia. 

Other Characters. — Concentrated sulphuric acid dissolves 
quinine with production of only a faint yellow color, which is 
not increased by warmth. — Quinine and its salts, heated on 
platinum foil, burn away entirely. — Most quinine salts when 
in solution have a beautiful blue fluorescence. They rotate 
the plane of polarization of light to the left. — Quinine is solu- 
ble in alcohol, ether, benzol, and chloroform. Quinine sul- 
phate is rather sparingly soluble in chloroform, and only 
slightly soluble in water. Its solubility in chloroform is 
increased by the presence in solution of quinidine and cin- 
chonine sulphates (Prescott), and its solubility in water is 
decreased by the presence in solution of ammonium sulphate 
(Carles). The slight solubility of quinine sulphate and iodo- 
sulphate in water distinguishes quinine from the other cin- 
chona alkaloids, including the " amorphous alkaloids," or 
quinoidine. 

Quinidine, C.^^H^^N^fi^ (the conquinine or conchinine of Hesse), ^B^ 
is an isomer of quinine. Its salts are fluorescent, and yield thal- 
leioquin with chlorine- or bromine-water and ammonia. They 
rotate the plane of polarization of light to the right. Quinidine 
is insoluble in water and sparingly soluble in ether (see Quinine, 
4th Analytical Eeaction). It is soluble in alcohol, benzol, and 
chloroform. It is less soluble than quinine in ammonia, 5 volumes 
of a saturated aqueous solution of quinidine sulphate requiring 60 
to 80 volumes of ammonia solution (sp. gr. 0. 96). Its sulphate is 
more soluble in water .and chloroform than quinine sulphate. 
Quinidine tartrate is soluble in water. The hydriodide is insolu- 
ble in water and dilute alcohol, and occurs as gritty crystals. The 
other cinchona alkaloid hydriodides, though more soluble than 
quinidine hydriodide, are sometimes precipitated from neutral 
concentrated solutions as amorphous or semi-liquid precipitates. 
These, however, are soluble in dilute alcohol. 

Cinchonidine, C^gH^^N^O.— The sulphate, (C^^H.^.^N^O),, H,SO^, 
SHgO, may be obtained from the mother-liquors from the crystal- 
lization of quinine sulphate. When perfectly pure, cinchonidine 
salts do not yield thalleioquin, and are not fluorescent. Even 
good commercial salts, however, nearly always give both reactions. 



522 ORGANIC CHEMISTRY. 

Cinchonidine salts rotate the plane of polarization of light to the 
left. Cinchonidine is insoluble in water and nearly so in ether, 
[See Quinine, 4th Analytical Reaction.) It is soluble in alcohol, 
benzol, and chloroform. It is less soluble in ammonia water 
than quinine, 5 volumes of a saturated aqueous solution of cin- 
chonidine sulphate requiring about 80 volumes of ammonia water 
(sp. gr. 0.96). It is true that cinchonidine is dissolved as 
readily as quinine if excess of ammonia w^ater is quickly mixed 
with the solution of the cinchonidine salt ; but from such a 
solution cinchonidine soon crystallizes out, while quinine 
remains dissolved for many hours. Cinchonidine sulphate 
(^Cinchonidmce Sulphas, U. S. P.), and hydriodide are soluble in 
water, but the sulphate, like quinine sulphate, is sparingly soluble 
in chloroform. Cinchonidine tartrate is insoluble in water; and 
in this form cinchonidine is usually separated from neutral solu- 
tions containing the other cinchona alkaloids except quinine, the 
filtrate from the precipitate of tartrate yielding cinchonine on the 
addition of ammonia. 

Cinchonine, C^gHggNgO, is an isomer of cinchonidine. The 
sulphate may be obtained from the mother-liquors from the crys- 
tallization of the quinine, cinchonidine, and quinidine sulphates, 
by adding sodium hydroxide to precipitate the alkaloid, washing 
with alcohol until free from other alkaloids, dissolving in sulphuric 
acid, and, after purifying the solution with animal charcoal, 
allowing to crystallize. When quite pure, its salts are not fluores- 
cent and do not yield thalleioquin, but as in the case of cinchoni- 
dine, most commercial specimens of cinchonine salts nearly always 
give both reactions. Cinchonine salts rotate the plane of polariza- 
tion of light to the right. Cinchonine is insoluble in water and 
nearly so in ether. {See Quinine, 4th Analytical Reaction.) It 
is soluble in chloroform, benzol, and alcohol. Chloroform con- 
taining one-fourth of its weight of alcohol dissolves cinchonine 
much more readily than either alcohol or chloroform alone. 
Cinchonine is insoluble in ammonia solution. Cinchonine 
sulphate {Cinchonince Sulphas, U. S. P.), tartrate, and hydriodide 
are soluble in water, and the sulphate, like quinidine sulphate, is 
soluble in chloroform. In mixtures of cinchona alkaloids this 
alkaloid is precipitated by alkali after the others have been succes- 
sively removed by ether, sodium tartrate, and potassium iodide. 

" Quinoidine,'' " chmoidine,^^ or the '^amorphous allmloid.'^ — 
Cinchona barks generally contain some alkaloid isomeric with 
quinine which, like quinine, is soluble in ether, but the ordinary 
sulphate and iodo-sulphate are not crystalline and are soluble. 
These salts are semi-solid resinous-looking substances. The iodo- 
sulphate is used in De Vrij's method for the separation of mixed 
alkaloids. Quinoidine is usually obtained along with the quinine, 
etc., extracted from the mixed alkaloids by ether, and remains in 
the mother-liquor, from which it is precipitated by an alkali. 



ALKALOIDS. 



523 



Quinicine aijd cinchonicine, are alkaloids produced by the action 
of heat on quinine or quinidine and on cinchonidine respectively. 
They also are isomers, Hesse says polymers, of the parent alka- 
loids. Both yield crystalline salts, Quiniretin is the name given 
to the brown or reddish-brown indifferent substance into which 
quinine in aqueous solution is converted when much exposed to 
light. 

Quinamine, Q^fi^J^fi^, is a fifth cinchona alkaloid obtained by 
Hesse in 1872 from the bark of Cinchona succirubra. Its solution 
is not fluorescent, and does not yield thalleioquin. Another 
alkaloid, cinchamidine, G^^^^fi, detected by the same chemist, 
is identical with hydrocinchonidine. 

Cupreine, O^^^^^O^, is an alkaloid discovered simultaneously 
by Howard and Hodgkin, by Paul and Cownley, and by Whiffen, 
in the bark of a Remijia (allied to Cinchona) and termed cuprea 
bark. It closely resembles quinine, but is sparingly soluble in 
ether. It may be converted into quinine by heating its sodium 
compound with methyl chloride; whence it appears that quinine 
is methyl-cupreine. The substance at first termed homoquinine or 
ultraqui7iine is a compound of cupreine and quinine, Q^fi^.^fi^, 

Hydroquinine, Q^^^^^O^, containing two more atoms of hydro- 
gen than are present in the quinine molecule, is an alkaloid asso- 
ciated with quinine in minute quantity in cinchona bark. It 
remains in the mother-liquor when quinine sulphate is crystallized 
from an acid solution. Its characters are closely allied to those 
of quinine and its therapeutic action is similar. It was discovered 
by Hesse. 

Constitution of the Cinchona Alkaloids. — This is not yet clear, 
though great advances have been made. In the course of the 
investigations derivatives of quinoline have been obtained, which 
more or less resemble quinine ; these are kairine, kairoUne, and 
thalline. 

Strychnine. 



Source. — Strychnine or strychnia, C21H22N2O2, exists, to the 
extent of about 1 percent., in Nux Vomica {Strychnos Nu.vvomica), 
also (Shenstone) in minute quantity in the bark of the Nux 
Vomica tree (false angostura bark) and to 1.0 or 1.5 percent, in 
St Ignatius' s bean {Strychnos Ignatius), partly, at least, in com- 
bination with strychnic or igasuric acid. Crow also found it in 
the bark of S. Ignatius. 

Preparation. — Nux Vomica seeds, disintegrated by steaming, 
and, after drying, grinding in a coffee-mill, are exhausted with 
alcohol, the latter is removed by distillation, the extract dis- 
solved in water, coloring-matters and organic acids precipitated 
by adding lead acetate, the filtered liquid evaporated to a 



624 ORGANIC CHEMISTRY. 

small bulk, the strycliiiine precij^itated by means of ammonia, 
the precipitate washed, dried, and exhausted with the recovered 
alcohol, the latter again removed by distillation, and the residual 
liquid set aside to crystallize. Crystals of strychnine having 
formed, the mother-liquor (which contains the brucine of the seeds) 
is poured away, and the crystals of strychnine are washed with 
alcohol (to remove any brucine) and recrystallized. This alkaloid 
is official {Strychnma, U. S. P.). 

Properties. — Strychnine occurs in colorless^ transparent, pris- 
matic crystals, or a white crystalline powder, odorless and having 
an intensely bitter taste, jDcrceptible even in solutions of 1 in 
700,000. Permanent in the air. It forms salts wdth acids. 
The sulphate {Strychnince Sulphas, U. S. P.), has the formula, 
(0211122^202)2112804, 5H2O. It is soluble in 31 parts of water. 
The citrate {C.^J1^^^^0;),,G^ILfi., 4H2O (or GH^O) dissolves, at 
60° F., in about 40 parts of water and 115 parts of alcohol. The 
hydrochloride has the formula C2iIl22N202,IICl,2H20, and is solu- 
ble in 35 parts of water. Strychnine nitrate {Strydmince Nitras, 
U. S. P.), C21H22N2O2, HN03,"'is official. A number of crystal- 
line, well-defined acids have been obtained from strychnine by- 
oxidation. 



Analytical Reactions of Strychnine. 

1. Place a very small fragment of str3'chnine on a white 
plate, and near to it also a small piece of potassium dichro- 
mate ; to each add one drop of concentrated sulphuric acid ; 
after waiting a minute or so for the dichromate to fairly tinge 
the acid, mix the two drops of liquid by means of a glass 
rod ; a beautiful purple color is produced, quickly fading into 
a yellowish-red. The following oxidizing agents may be used 
in place of the dichromate: — lead peroxide, black manganese 
oxide, potassium ferricyauide, potassium permanganate, or 
ammonium vanadate. 

This reaction is highly characteristic and delicate; a minute 
fragment of strychnine dissolved in much dilute alcohol, or, 
better, chloroform, and one drop of the solution evaporated to 
dryness on a porcelain crucible-lid or plate, yields a residue 
which immediately gives the purple color on being oxidized in 
the manner directed. 

2. Strychnine evaporated with nitric acid, and the residue 
moistened with alcoholic potassium hydroxide, and again evap- 
orated, gives a yellow^ coloration, passing into reddish-violet 



ALKALOIDS. 525 

on addition of more potassium hydroxide, and becoming yellow 
again on the addition of water. When atropine is treated 
in the same way a violet residue is obtained which becomes 
colorless on adding water. 

Other Reactions. — Concentrated sulphuric acid does not act on 
strychnine, even at the temperature of boiling water, a fact of 
which advantage is taken in separating strychnine from other 
organic matter for the purposes of toxicological analysis. — 
Potassium thiocyanate produces, even in dilute solutions of 
strychnine, a white precipitate, which, under the microscope, is 
seen to consist of tufts of acicular crystals. — Concentrated nitric 
acid does not color strychnine in the cold, and on heating only 
turns it yellow. 

The Physiological Test. — A small frog placed in an ounce of 
water to which yi^ of a grain of strychnine salt (acetate) is added, 
is, in two or three hours, seized with tetanic spasms on the 
slightest touch, and dies shortly afterward. 

Strychnine has an intensely bitter taste. Cold water dissolves 
only 6 4^0 part; yet this solution, even when largely diluted, is 
distinctly bitter. Alcohol is a much better solvent. The salts 
of the alkaloid are more soluble. 

Brucine, or Brucia, C.^gH^gNgO^, 4H2O, is an alkaloid accom- 
panying strychnine in Nux Vomica and St. Ignatius' s bean to the 
extent of about two percent. It is readily distinguished by the 
intense red color produced when nitric acid is added to it. Igas^irine, 
once supposed to to be a third alkaloid of nux vomica, has been 
shown by Shenstone to be only a mixture of brucine and strychnine. 

Curarine, Q^^^^^O, the active principle of the arrow-poison 
termed curari, urari, ourari, wourali, or woorara, prepared from a 
/Strychnos, resembles strychnine in giving a color reaction on 
oxidation, but the color is more permanent. Potassium iodide and 
cyanoplatinate do not with curarine afford precipitates which 
crystallize from alcohol like those of strychnine. Curarine, also, 
is readily soluble in water. Unlike strychnine, curarine is reddened 
by sulphuric acid; further it is not dissolved out by ether from an 
acid or alkaline liquid. Curari appears to vary much in strength 
and quality. It is probably a mixture of vegetable extracts. 
Citrine, CjgHjgNO^, also is said to be present. 

Distinction of Brucine from Morphine. — The red coloration pro- 
duced by the action of nitric acid on brucine is distinguished from 
that yielded with morphine, by the action of reducing agents 
(such as stannous chloride, sodium thiosulphate or hydrosul})hide), 
which decolorize the morphine red, but change that of the brucine 
to violet and green (Cotton). The solution of brucine in the 
nitric acid should be heated to the boiling-point, diluted with 
water, and the stannous chloride then added. 



526 ORGANIC CHEMISTRY. 

QUESTIONS AND EXEECISES. 

What alkaloids are more or less characteristic of the different varieties 
of cinchona bark ? In what form do they occur ? — By what method may, 
quinine sulphate be obtained ? — Give the characters of quinine sulphate/ 
— Describe the tests for quinine. — Show howquiuidine or cinchoniue sul- 
phates may be proved to be present in commercial quinine sulphine. — 
How are cinchonine and quinine distinguished from morphine ?— Whence 
is strychnine obtained ? — Describe the process for the isolation of strych- 
nine. — Give the characters of strychnine.— Describe the tests for strych- 
nine. — By what reagent is brucine distinguished from strychnine? — 
Distinguish between brucine and morphine. 



ALKALOIDS OF LESS FREQUENT OCCURRENCE. 

AcALYPHiNE is the well-marked alkaloid of Acalypha herb, or 
Rupi, an expectorant used in place of senega. 

AcoNiTiNE, {Aconitma, U. S. P.), or AcONiTiA, Cg^H^^NOj^, 
is an alkaloid obtained from Aconite {Aconitum Napellus) root 
{Aconitum, U. S. P.). The alkaloid itself is only slightly soluble in 
water; it occurs in the plant in combination with a vegetable 
acid, forming a soluble salt. 

Preparation. — Dunstan' s process for the preparation of aconitine 
consists in dissolving out the alkaloid from the root with fusel 
oil, and shaking the solution with sulphuric acid, which takes up 
the aconitine; the acid is then freed from resin by shaking with 
chloroform, and the alkaloid liberated by ammonia in the presence 
of ether, which dissolves it as soon as it is liberated. The aconi- 
tine and benzaconine thus obtained are converted into hydrobro- 
mides, and separated by fractional crystallization. 

Properties. — Aconitine usually occurs as a w^hite powder. It 
has been obtained and studied in the crystalline state by Groves, 
Wright, Williams, and others. It is very slightly soluble in cold 
w^ater, more so in hot, and much more soluble in alcohol, in ether, 
and in chloroform. When rubbed on the skin, it causes a tingling 
sensation, followed by prolonged numbness. The thousandth 
part of a grain on the tip of the tongue produces, after a minute 
or so, a characteristic tingling sensation and numbness; larger 
quantities rubbed into the skin causes numbness. Sulphuric acid 
turns it of a yellowish and, afterward, dirty violet color. 

According to Wright, who worked in conjunction with Groves 
and Williams, Aconitum Napellus yields, chiefly, crystalline aconitine, 
^33^43^0,,, wdthsomecrystallinep.se?/ffaco;u?'me, C.^pH3<,]S'0^2. Dun- 
stan and Umney found, in addition to aconitine (C^gH^.NO^.,), 
Dunstan and Ince), aconine, and an amorphous alkaloid, 
napelline or isaconitine, the salts of which are also amorphous. 
Aconitine is readily hydrolyzed into aconine, Cj^H^gNOj,,, and 
benzoic acid (Dunstan and Passmore). Aconine is physiologically. 



ALKALOIDS. 527 

inert; benzaconine, Q^Jl^^{QJAfiO)NO-^Q, is active but is not a 
poison; while acetyl-benzaconine, or aconitine, C24Hg^(CH3CO) 
(CgH5G0)N0jQ, is a most powerful poison. The constitution of 
aconine is not yet known. 

The tuberous roots of Aconitum Ferox and other species consti- 
tute the bish or bikh of India. It chiefly contains the variety of 
aconitine termed psuedaconitine. Some of the aconitine of phar- 
macy is pseudaconitine. 

According to Paul and Kingzett, the alkaloid of Japanese 
aconite has the formula CggH^gNOg, while Wright and Menke 
state that the formula is C^gHggNgOgi, and name it japaconitine. 

Aconitum heterophyllum^ Atis or Atees Wakhma contains no aconi- 
tine, but an alkaloid afeesine having the formula C^gH^^N20^. 

Aristolochine, an alkaloid, and Aristolochin, a substance 
having the physiological properties of aloin, also volatile oil, are 
obtained from some of the species of Aristolochia. The ofiicial 
drugs {Serpentaria, U. S. P.), are A. Serpentaria or Virginia 
Snakeroot and A. reticulata (Texas serpentaria). 

ASPIDOSPERMINE, Q^^^^fi^, is an alkaloid of Quebracho 
bianco bark (Fraude). Another alkaloid is quebrachine, C^^^^fi^ 
(Hesse). The latter chemist has isolated four other closely 
related alkaloids; also two from Quebracho Colorado bark. 

Atropine or Atropia, Cj^H^^NOg (Atropina, U. S. P.). — 
This alkaloid was formerly considered to exist ready formed in 
the Belladonna, or Deadly Nightshade (Atropa Belladonna) {Bella- 
donnce Folia; Belladonnce Radix, U. S. P.), as soluble acid atro- 
pine malate. But the observations of Messrs Schering and the 
researches of Will indicate that it is not atropine but an isomer 
of atropine, namely hyoscyamine, which is the alkaloid chiefly 
and often solely present, and that the treatment with alkali, 
during the process of extraction, converts the hyoscyamine 
into atropine. Hyoscyamine solutions rotate the plane of polari- 
zation of light to the left; atropine has no optical rotary power. 
Both possess the property of dilating the pupil of the eye. See 
also Hyoscyamine. 

Preparation. — Atropine may be obtained by exhausting the root 
with alcohol, precipitating the acid and some coloring-matter by 
adding lime, filtering, adding sulphuric acid to form atropine sul- 
phate (which is somewhat less liable to decomposition during sub- 
sequent operations than the alkaloid itself), recovering most of the 
alcohol by distillation, adding water to the residue, and evapo- 
rating until the remaining alcohol is removed; solution of potassium 
carbonate is then poured in until the liquid is nearly, but not quite, 
neutral, whereby resinous matter is precipitated; the latter is fil- 
tered off", excess of potassium carbonate then added, and the liber- 
ated atropine dissolved out by shaking the liquid with chloroform. 
The latter solution, having subsided, is se})araled, the chlorot'orni 
recovered by distillation, the residual atropine dissolved in warm 



528 ORGANIC CHEMISTRY. 

alcohol, coloring-matter removed by digesting the liquid with 
animal charcoal, and the solution filtered, evaporated, and set 
aside to deposit crystals. 

Atropine is sparingly soluble in water, the liquid having an 
alkaline reaction. It is more soluble in alcohol and ether. 

Tests. — With chlorauric acid, atropine solutions yield a yellow 
precipitate. One drop of a dilute aqueous solution of atropine 
(two grains to the ounce) powerfully dilates the pupil of the eye. 

Baryta water decomposes atropine into tropine, CgH^^NO, and 
tropic acid, CgHjoOg, a molecule of water being absorbed : 

Ci,H,3N03 + H,0 - CeH^^NO + C,H,o03. 

Hence atropine would seem to be the tropine ester of tropic acid. 
By heating troj)ine and tropic acid in sealed tubes Ladenburg has 
succeeded in reproducing atropine, and has thereby rendered pos- 
sible the synthesis of this alkaloid from its elements. Similarly a 
number of new alkaloids, known as trope'ines and analogous to 
atropine, have been obtained by treating tropine with other acids. 
One of these is homatropine (see below) which is the tropine ester 
of mandelic acid. By removing the elements of water from tropine, 
Ladenburg obtains tropidine, CgH^gN, closely related to ecgonine 
(p. 532) and anhydro-ecgonine. 

Tropine, when neutralized with mandelic acid, and the salt so 
formed heated with hydrochloric acid, yields homatropine, the 
hydrobromide of which, C^gH2,N03,HBr, is official {HomatropiiKE 
Hydrohromidum, U.S. P.). Homatropine hydrobromide is a white 
crystalline powder or aggregation of minute trimetric crystals, 
soluble in 5. 7 parts of cold water, and in 32. 5 of alcohol. The 
dilute aqueous solution powerfully dilates the pupil of the eye. A 
2 percent, aqueous solution is not precipitated by the cautious 
addition of solution of ammonia previously diluted with twice its 
volume of water [distinction from atropine]. About a tenth of a 
grain moistened with two minims of nitric acid and evaporated to 
dryness on the water-bath yields a residue which is colored yellow 
by an alcoholic solution of potassium hydroxide [distinction from 
atropine, hyoscine, and hyoscyamine] . If about a tenth of a grain 
be dissolved in a little water and the solution be made alkaline 
with ammonia and shaken with chloroform, the separated chloro- 
form will leave on evaporation a residue which will turn yellow 
and finally brick-red when warmed Avith about fifteen minims of 
a solution of two grains of mercuric chloride in a hundred minims 
of proof spirit; for Gerrard, Schweissinger, and Fliickiger have 
observed that homatropine (Ladenburg' soxytoluyltropeine, which 
is a physiologically similar but less powerful and therefore some- 
times more useful alkaloid than atropine), like hyoscyamine and 
atropine, has unusually powerful alkaline properties, precipitating 
mercuric oxide from mercuric solutions, reddening phenolphtha- 



ALKALOIDS. 529 

lein, and, with the aid of heat, blackening calomel. No other 
ordinary alkaloids are so powerfully alkaline. 

In the so-called Japanese belladonna {Scopola Japonica) there 
occurs scopoleine, an alkaloid resembling, but more powerful than, 
atropine (Eykman); but Schmidt considers that only atropine, 
hyoscyamine and hyoscine are present, See p. 536. 

Preparations. — The alkaloid li^^li {Atrojnnd)', its sulphate {Atro- 
pince Sulphas), a white crystalline powder soluble in water (made 
by neutralizing atropine with sulphuric acid); an extract {Extrac- 
tum BeUadomice Follorum); a fluidextract {Fluidextractum Bella- 
donncE Eadicis); a liniment {Linimentum BelladonncE); and an oint- 
ment ( Unguentum BeUadomice). 

The fluorescence of alkaline solutions of extract of belladonna 
is caused by chrijsatropic acid (Kunz), which appears to be identical 
with the fluorescent scopoletin, C^oHgO^, found in Japanese bella- 
donna by Eykman. 

Baptitoxine. — Schroeder gives this name to a poisonous alka- 
loid in Baptisia tinctoria, wild indigo, in which he also finds the 
glucosides baptisin and baptin. 

Beberine, Bebirine, or Bibirine, C^gHgjNO^, is an alkaloid 
in the bark of Bebeeru, or Bibiru [Nectandra Bodicei). 

Beberine sulphate, (CjgH2iN03)2, H.^SO^, may be prepared by ex- 
hausting the bark with water acidulated with sulphuric acid, con- 
centrating, removing most of the acid by adding lime, filtering, pre- 
cipitating the alkaloid with ammonia, filtering, drying, dissolving 
in alcohol (in which some accompanying matters are insoluble), 
recovering most of the alcohol by distillation, neutralizing with 
dilute sulphuric acid, evaporating to dryness, dissolving the resid- 
ual sulphate in water, evaporating to the consistence of a syrup, 
spreading on glass plates, and drying the product at 140° F. 
(60° C). Thus obtained, it occurs in dark-brown translucent 
scales, yellow when powdered, strongly bitter, soluble in water 
and in alcohol. It is probably a mixture of beberine sulphate, 
nectandrine sulphate, and other alkaloidal sulphates. 

Tests. —Alkalies give a pale-yellow precipitate of beberine when 
added to an aqueous solution of a salt of the alkaloid; the precipi- 
tate IS soluble in ether. With potassium dichromate and sulphuric 
acid, beberme gives a black resin, and with nitric acid a yellow 
resin. 

^ Buxine, from the bark of Buxus sempervirens ; pelosine, or 
cissampeline, from the dried root {Pareira, U. S. P.), of Chondro- 
dendron tomentosum and of Cissampetos Pareira; and paricine, 
from a fiilse Para cinchona-bark, are probably identical with beber- 
ine (Fliickiger). 

Nectandrine C,oH^,N203,4H,0).— Maclagan and Gamgee discov- 
ered this alkaloid in Bebeeru-wood. It diflers from beberine in 
fusing when placed in boiling water, in being much less soluble in 
ether, and in giving with concentrated sulphuric acid and black 
34 



530 ORGANIC CHEMISTRY. 

manganese oxide a beautiful green and then a violet coloration. 
They considered that two other alkaloids exist in Bebeeru-wood. 

Berberine, CjoH^^XO^, is an alkaloid existing in several plants 
of the natural order Berberidacece, in Calumba-root {Galumba, 
U. S. P.), in the root of Coptis Teeta or Mishmi Bitter, an Indian 
tonic, in the dried stem of Coscinium fenestratum, and in many- 
other yellow woods. Hydrastis canadensis or Golden Seal, contains 
berberine, though a second alkaloid, hydrastine, related to narco- 
tine and to papaverine, and even a third, are said to be present, 
all, in Perkin's opinion, benzene derivatives of iso-quinoline. 
Hvdrastine acid tartrate, C,,H„,NO., C,H^0.,4H„0, has been 
obtained in the crystalline form. The dried rhizome and rootlets 
are official, {Hydrastis, U. S. P.), and these are the source of the 
Flaidextractum Hydrastis, U. S. P., and Tinctura Hydrastis, 
U. S. P. The root of Berberis vulgaris contains berberine and 
o.vyacanthine, C^gH^^XO^, (Eiidel), as well as berbamine, CjgH^gXOy, 
(Hesse). Xanthorrhiza apiifoUa, an old American tonic, and, 
apparently, Xantho.vylon Fraxineum, or Prickly Ash, also contain 
berberine. The rhizome of Menispermum Canadense, Yelloiv 
Barilla, or Canadian Moonseed, contains, according to Maiscli, a 
colorless alkaloid as well as berberine. The color of the tissues of 
these plants is apj^arently due to berberine; for the alkaloid itself 
is remarkable for its beautiful yellow color. 

Br epar at ion.— ^Jievhevine is readily extracted by boiling the raw 
material with water, evaporating the strained liquid to a soft 
extract, digesting the residue in alcohol, recovering the alcohol 
by distillation, boiling the residue with dilute sulphuric acid, 
filtering and setting aside; berberine acid sulphate, C2oHj,XO^, 
H.,SO^, which is sparingly soluble, separates out and may be puri- 
fied by recrystallization from hot water. The alkaloid itself is 
obtained by shaking lead hydroxide with a hot aqueous solution 
of berberine acid sulphate (Procter). 

Tests. — When a dilute solution of iodine and potassium iodide 
is added to a solution of any salt of berberine in hot alcohol, large 
excess of iodine being carefully avoided, brilliant green spangles 
of a periodide, C.,^H^.XOJ.„HI, are deposited. The reaction is 
sufficiently delicate to form, according to Perrins, an excellent 
test for the presence of berberine. This iodo-compound polarizes 
light, and has other analogies with herapathite. 

Berberine itself is not official, but plants in which it occurs are 
used as medicinal agents in all parts of the world. 

Caffeine, or Theixe, or Guaraxine (methvl-theobromine 
(Caffeina, U. S. P.), C,H„Np,, H,0.— This alkaloid occurs in 
Tea, 2 to 4.5 percent.; Coffee, 1.2 percent.; Mate or Paraguay 
Tea, 0. 2 to 2 percent. ; Guarana, 5 percent. ; and the Kola-nut, 
0. 5 percent. Infusions and preparations of these vegetable ])ro- 
ducts are used, chiefly as beverages, by three-fourths of the human 
race. It is remarkable that the instinct of man, even in his sav- 



ALKALOIDS. 531 

age state, should have led him to select, as the basis of beverages 
in such common use, just the four or five plants which out of many 
thousands are the only ones, so far as we know, containing caf- 
feine. 

Caffeine is volatile. Considerable quantities may be collected 
by condensing the vapors evolved during the roasting of coffee on 
the large scale. A decoction of tea, from which astringent and 
coloring-matters have been precipitated by solution of lead sub- 
acetate, and which has then been acidulated with sulphuric acid 
and well washed with chloroform, the latter fluid evaporated, and 
the residue dried at 100° C, yields an average of a little over 3 
percent, (of the tea) of anhydrous caffeine. It may be crystallized 
from alcohol or by sublimation. It forms salts with acids ( Caffeina 
Citrata, U. S. P., CgH^^N^O^, CgHgO^) ; they are decomposed by 
water. 

Cafein Citrata Effervescens, U. S. P. , is made by mixing caf- 
feine citrate with tartaric and citric acids, sodium bicarbonate, and 
sugar, heating and stirring until the mixture assumes a granular 
character. 

Test. — Concentrated nitric acid, or, better, a mixture of potas- 
sium chlorate and hydrochloric acid, rapidly oxidizes caffeine, 
forming compounds which with ammonia yield a beautiful purple- 
red color, resembling the murexid obtained under similar circum- 
stances from uric acid ; the oxidation must not be carried too far. 
On boiling with potassium hydroxide caffeine yields methylamine. 

The main physiological action of caffeine on the system is a stimu- 
lating one especially affecting heart-muscle. 

The commercial value of tea depends upon its appearance and 
on the flavor and odor of the infusion, the percentage of caffeine 
not varying much. China tea* contains rather less caffeine and much 
less astringent matter than tea from Ceylon or India. Tea infused 
in boiling water for five minutes yields somewhat more than half 
its caffeine to the fluid. 

Graphic formula for Caffeine. — See p. 539, 

Capsicine. — Felletar obtained from Capsicum-fruit {Capsicum, 
U. S. P.), which when ground forms Cayenne Pepper, a volatile 
alkaloid having the smell of conine. Thresh has obtained crys- 
talline hydrochloride and sulphate. The latter chemist has also 
succeeded in isolating the active principle of capsicum, which he 
has termed capsaicin, CgHj^Oj, a crystalline non-alkaloidal exces- 
sively acrid subste,nce. Its exact chemical character is not yet 
made out, but Micko regards it as a nitrogen compound possess- 
ing a slightly acid phenolic character and gives it the fornuila 
CigH^gNO;,. According to Thresh a similar very pungent princi- 
ple occurs in ginger (gingerol) and in grains of paradise (paradol), 
bodies probably isomeric with capsaicin. {Sec also Capsicin, p. 
477). 

Carpaine, Cj^HgjNO.^, occurs in Carica papaya. 



532 OBGANIC CHEMISTRY. 

Cephaeline, Cj^H2(jN02, is an alkaloid found in the root of 
Cephaelis Ipecacuanha ; about one-third of the total alkaloid in 
the root is cephaeline, the remainder being principally emetine (a 
third alkaloid is present in small quantity). Cephaeline is not 
equal to emetine as an expectorant, but is superior as an emetic ; 
it is rapidly decomposed when boiled with alcohol. See also Eme- 
tine. 

Cocaine, Ci,H2^X0^, is an alkaloid of Erythroxylon Coca, the 
leaves of which act powerfully as a restorative to the human 
system. The alkaloid itself and its hydrochloride are both official 
[Cocaina, U. S. P., and Cocaincp, Hijdrochloridum, U. S. P.). 
Cocaine and its salts may be prepared by agitating with petroleum 
spirit a concentrated, acidulated, aqueous extract of the leaves 
made alkaline with sodium carbonate, well shaking the separated 
spirit with acidulated water, treating the separated acid liquid 
with ether and excess of sodium carbonate, w^ashing out the alka- 
loid from the ether with water containing hydrochloric acid, and 
finally evaporating the resulting aqueous solution of the hydro- 
chloride to the crystallizing point. Cocaine may be precipitated 
with ammonia and recrvstallized from alcohol, ether, or warm 
benzene. It melts at 204. 8^ to 208. 4° F. (96^ to 98° C. ). From this 
pure cocaine the pure and very soluble hydrochloride may be pre- 
pared by neutralizing with hydrochloric acid and crystallizing.. 

Prolonged contact of cocaine with hot water, acids, alkalies, or 
even alcohol, is undesirable, as cocaine readily breaks up into ben- 
zoyl-ecgonine, and methyl alcohol, Cj_H2iN'0^-|-H20=CjgHi9]Sr04 
+ CH3OH, benzoyl-ecgonine afterward yielding ecgonine and 
benzoic acid, Ci6H,9NO, + H.O = C.H^.NO, + C-HgO^. Other 
bases occur in coca besides cocaine. Paul and Cownley, also Giesel, 
find cimiamijl-cocaine. Hesse finds t\Vo amorphous bases which he 
names cocamine and cocaidine. Libermann finds several bases, 
one of which is poisonous, namely, isatropyl-cocaine, CjyH2.^iS'0^ 
(identical with Hesse's cocamine), containing an isatropyl group 
in place of the benzoyl group in ordinary cocaine. All these bases 
are easily hydrolyzed, yielding ecgonine ; the latter with benzoic 
anhydride yields benzoyl-ecgonine ; and this with methyl iodide, 
yields benzoyl-methyl ecgonine, or ordinary cocaine. A series of 
"cocaines" can be produced by introducing other groups into 
ecgonine instead of the benzoyl groups. 

Another alkaloid (benzoyl-pseudo-tropeine), yielding instead of 
ecgonine a compound isomeric with tropine, also occurs in coca 
(Giesel ; Liebermann). 

Cocaine hydrochloride occurs in colorless monoclinic prisms 
soluble in water, chloroform, alcohol, amyl alcohol ; very slightly 
in ether ; not readily decomposed even when boiled in water. The 
free alkaloid is readily decomposed by water, especially when the 
solution is warmed. The solution in water has a bitter taste ; gives 
a purjDle precipitate with permanganates ; and a white precipitate 



ALKALOIDS. 633 

with ammonia. Its solution produces on the tongue a tingling 
sensation followed by numbness. The aqueous solution dilates 
the pupil of the eye. It gives no color to cold concentrated acids, 
but chars with hot sulphuric acid. Evaporated to dryness on a 
water-bath with nitric acid, and treated with alcoholic potash, it 
develops an odor resembling peppermint. Besides its action as a 
restorative when taken internally, cocaine brought into contact 
wdth the mucous membrane of the eye, mouth, throat, etc., or 
when injected, produces local anaesthesia. According to Squibb, 
good coca leaves yield 0. 5 percent, of cocaine. Cocaine may be 
detected in presence of other alkaloids by giving a yellow precipi- 
tate of cocaine chromate with either potassium chromate or chromic 
acid in presence of free hydrochloric acid. 

CoLCHiciiSrE, [Colchicina, U. S. P.), the active principle of 
Colchicum autumnale (Colchici Cormus, U. S. P. ; Colchici Semen, 
U.S. P. ), is said to be an alkaloid, although some investigators think 
it has more of the characters of a neutral substance. Hertel states 
that ebullition with acidulated water converts it into colchiceine 
and methyl alcohol. Giesel says it may be crystallized from 
chloroform, and offers the following formulae for it and its deriva- 
tive ; colchicine, C^^YL.^,{OC'R.^'^0.^ ; colchiceine, C^JI^^{OB)^0,. 
The most active medicinal preparation is an extract made from the 
fresh seeds by digestion in large volumes of alcohol and subsequent 
digestion of the marc in hot water. The extracts left on evaporat- 
ing the two liquids separately are to be carefully mixed (Mols). 

CONIINE, CONIA, CONYLIA, CONICINE, or CiCUTINE, CgHj^N, 

a-normal-propyl-piperidine, C^'il-^Q'N(CJI^). This alkaloid is a vola- 
tile liquid, occurring in the fruit (Conium, U. S. P.), of Hemlock 
[conium maculatum) in combination with an acid (malic ?). Accord- 
ing to Petit its boiling-point is 170° C, and its density 0.846. It 
forms crystalline salts. 

Preparation. — Coniine may be obtained by distilling hemlock- 
fruit with water rendered slightly alkaline with sodium or potassium 
hydroxide or by similarly treating the fresh juice of the leaves. 
The crude alkaloid is a yellow oily liquid, floating on the water 
that distils over; by redistillation it is obtained colorless and trans- 
parent. Coniine may also be obtained from Conium by the offi- 
cial assay process. 

The salts of coniine are odorless, but when moistened wath solu- 
tion of an alkali yield the alkaloid, the strong odor of which, at 
once recalling hemlock, is characteristic. 

Tests. — Sulphuric acid turns coniine purplish-red, changing to 
olive-green; nitric acid a blood-red; chlorauric acid i)roduces a 
yellowish-white precipitate, chloroplatinic acid no preeipitnte in 
aqueous solutions. 

Hemlock also contains methyl coniine, (C^H^,,)CH.jN (Kekulo 
and Von Planta), and conhydrine, C^H,.NO. The latter by dehy- 
dration yields a base. CgH,,N. 



I 

i 
I 

' i 

I 



534 ORGANIC CHEMISTRY. 

According to Schiff, coniine, isomeric, at least, with the natural 
alkaloid may be produced artificially by action of ammonia on 
butyric aldehyde and destructive distillation of the resulting com- 
pound. Ladenburg has produced coniine, identical with the 
natural alkaloid, from a-picoline. Coniine may now therefore be 
said to be a product of organic synthesis, producible from its 
elements. 

COEYDALINE, CggHg^NO^, occurs together with several other 
alkaloids in the tubers of Corydalis cava, in which it Avas dis- 
covered by Wackenroder in 1826. It forms colorless prismatic 
crystals which are practically insoluble in cold water, readily solu- 
ble in ether and chloroform, and sparingly soluble in alcohol. 
The crystals melt at 134.5° C. ' Both crystals and solutions 
quickly assume a yellow color on exposure to light or on heating. 
The alkaloid forms a number of salts, some of which crystal- 
lize well. 

CusPARiNE, C20HJ9XO3, with cusparidine, CjgHj.NOg, and gali- 
pine, C20H21NO3, are alkaloids occurring in the bark of Galipea 
eusparia, or true Angostura Bark. The bitter principle, angos- 
turin, is not an alkaloid. 

CYTisi:f^EorULEXiNE, Cj^Hj^NgO, is an alkaloid found in labur- 
num and furze, and is identical with sophorine, from Sophora 
tomentosa. 

Daturine. — See Hyoscyamine. 

Delphixe, or Delphixixe and Delphinoidine are the 
j^oisonous alkaloid of Stavesacre (Delphinium Staphisagria). The 
powdered seeds of the plant are employed to kill the pediculi of 
animals. The seeds {Staphisagria, U. S. P.), contain about 25 
percent, of oil. 

DiTAMiXE, CjpHjgNO.^ (Jobst and Hesse), is an alkaloid of 
'^Dita," or bark of Echites scholaris or Ahtonia scholaris a 
reputed febrifuge. Others are echi famine or ditaine and echite- 
nine. Oberlin and Schlagdenhauffen state that the allied Ahtonia 
constricta (the bark of which is said to have advantages over the 
hop as a dietetic bitter) contains a crystalline alkaloid, ahtonme 
and uncrystallizable rt/s?'o;»"c/;^e. Alstonine seems to be allied to 
strychnine. 

DuBOisiXE. — See Hyoscyamixe. 

Emetixe, C^.H22N02. — This alkaloid is one of the active prin- 
ciples of the root of Cephaelis Ipecacuanha {Ipecacuanha, U. S. P.). 
It occurs to the extent of 1 to 2 percent, in the root (less in the 
stems) in combination with ipecacuanhic acid. The nitrate is 
peculiarly slightly soluble in water (Lefort). In Pulvis IpecacuanhcB 
et Opii, U.S. P., or Dover's Powder (Powdered Ipecacuanha, 1 part; 
Powdered Opium, 1 part; and Sugar of Milk, 8 parts), minute 
division of the active ingredients is promoted by prolonged tritu- 
ration. {Fluidextractum Ipecacuanhce, U. S. P.), contains 1.75 
Gm. of the alkaloids of the root in 100 Cc. Ipecacuanha Wine 



ALKALOIDS. 536 

( Vinum Ipecacuanhfp,, U. S. P.), is a mixture of 1 part by volume 
of Fluidextractum Ipecacuanhce with one of alcohol and eight of 
white wine. Cephaeline (J percent, in Brazilian and l\ percent, 
in Columbian, according to Paul and Cownley) and small quantities 
of a third alkaloid, are also found in ipecacuanha. 

The Indian substitute for ipecacuanha is the dried leaf of Tylo- 
phora asthmatica. Its active principle has not been satisfactorily 
determined, but would seem to be the alkaloid tylophorine 
(Hooper). 

Gelsemine, CjgHggNgO^. — This is one of the alkaloids of Gel- 
seinium nitidum, or Carolina Yellow Jasmine (Ge/semmw,U. S. P.), 
in the tissues of which plant the gelsejiiinic acid of Wormley, and 
rescidin, Cj^H^^Og the fluorescent glucoside of the Horse Chestnut 
and of many other plants, are also present. Like strychnine, 
gelsemine is not apparently affected by concentrated sulphuric 
acid. Nitric acid does not color it. A mixture of sulphuric acid 
and black manganese oxide colors it a crimson red, changing to 
green. In Gelsemium elegam, Crow finds an allied alkaloid which 
does not resist the action of sulphuric acid. Oelseminhte, 
C^^^^^0.^,\^ Sinoihev G^e&emmm alkaloid, said to be more pow- 
ertiil than gelsemine. 

Grindeline is the name given by Fischer to a bitter crystalline 
alkaloid he extracted from Grindelia (robusta), U. S. P. The 
plant also contains a resin and a volatile oil. 

Homatropine. — See Atropine. 

Hydrastine. — See Berberine. 

Hyoscine or Scopolamine. — Besides hyoscyamine, Laden- 
burg finds in henbane some hyoscine, Cj^H2jN0^, identical with 
scopolamine from Scopola afropoides and S. carniolica. Hyoscine 
hydrobromide is official [Hijoscmce Hijdrobromidum, U. S. P.). 

Hyoscyamine, C^^H^.^NO^, occurs in the leaves Niger Hyoscy- 
amus, U. S. P. and other parts of Henbane (ILyosajamus), Bella- 
donna, Stramonium, and various species of Scopola; also 
(Dymond) in Lettuce. It forms brilliant colorless needles. Its 
salts also are crystalline. Its effect on the eye is similar to that of 
atropine. The researches of Ladenburg show that hyoscyamine 
is the tropate of an alkaloid isomeric with tropine. The hydro- 
bromide and sulphate are official {Jlyoscyaonince Hydrohromldum 
and Hyoscyamime Sulphas, U. S. P.). [See Atropine.) 

The alkaloids in Datura Stramonium, or Thornapple (Stramo- 
nium, U. S. P.), Dhatura the leaves of Datura fastuom and D. 
Met el, and the seeds of Datura fastuom, and in Duboisia Myopo- 
roides, were formerly su])posed to be distinct alkaloids, called 
respectively Daturine and Dubolsine, but are identical with hyos- 
cyamine, which is isomeric with atropine (Ladenburg). According 
to Schmidt, the alkaloid of Dulmis'ta myoporoldcs is sometinu^s 
hyoscyamine and sometimes hyoscine or scopolamine. Pseudo- 
hyoscyamine, Cj^Hg.jNOg, also occurs in the latter plant. Bees 



536 ORGANIC CHEMISTRY. 

which sip from the flowers of stramonium are said to deposit 
poisonous honey. ; 

Hyoscyamine melts when heated to between 108° and 109° C, 
and then is soon converted into atropine. Its solutions in alcohol 
or ether are stable, but the presence of a very minute amount of 
fixed caustic alkali, or of alkali-metal carbonate, causes its com- 
plete conversion into atropine. With chlorauric acid its salts 
give a yellow crystalline precipitate, soluble in boiling water 
acidulated with hydrochloric acid, and again deposited, as the 
solution cools, in brilliant, golden-yellow scales. 

Jaborandine and Jaborine.— iS^e Pilocarpine. 

Jervine, C^gH^.NOg, occurs in Veratrum album, White Helle- 
bore, and V. viride,^ American White Hellebore, {Veratrum, 
U. S. P.). Its salts are much less soluble in water than those of 
veratrine. According to Bullock, Verati-um viride contains another 
alkaloid — veratroidiiie ; and, according to Mitchell, Veratrura 
album also contains another alkaloid which he terms veratralbine. 
Tobien gives the formula of Jervine as Cg.H^.NgOg, and of vera- 
troidine as C.jH.gN.Pj^^, or Cj^Hg.NO.. According to Wright, 
Veratrum album contains jervine, C^gHg^NO^ ; pseudojervine, 
CggH^.^NO.; rubijervine C2fiH^3N02; veratralbine, CggH^.^NOj; and 
traces of veratrine, Cg.HgjNO^^. The same author finds Veratrum 
viride to contain jervine, pseudojervine, cevadine, C32H^gN09, 
rubijervine and traces of veratrine and veratralbine. Pehkschen 
finds jervine, pseudojervine, and veratroidine, while Salzberger, 
besides jervine, rubijervine, and pseudojervine, finds protovera- 
trine, C32H.jNOj„ and protoveratridine, C2fiH^.N0g. Salzberger 
confirms Wright and Luff's formula for jervine. 

Lobeline. — A volatile fluid alkaloid first isolated from the 
dried flowering herb Lobelia inflata [Lobelia, U. S. P.), by Proctor. 
In the pure state it is inodorous, impure it smells slightly, but 
mixed with ammonia emits a strong and characteristic smell of 
the plant. With acids it forms salts. A solid alkaloid is said to 
be present. 

LuPUiiiNE is stated by Greismayer to be a liquid volatile alka- 
loid contained in the Hop, Humulus Lupulus {Humulus, U. S. P.). 
The powdered trictromes of the plant are ofl3cial {Lnpulinnm, 
U. S. P.). 

Nectandrine. — See Berberine. 

Nicotine, CjoHj^Nj. — This is a volatile liquid alkaloid, form- 
ing the powerful active principle of Tobacco {Nicotiana Tabacum), 
nicotine malate and citrate being the forms in which it occurs in 
the leaf. Its odor is characteristic; like conine, it yields a pre- 
cipitate with chlorauric acid, but, unlike that alkaloid, its aqueous 

^ The name of Green Hellebore \?, sometimes applied to this drug, but 
properly belongs to Hellehoriis viridis {nee " Helleliorin " p 501), which is 
used medicinally in some parts of Europe. — Hanbmy. 



ALKALOIDS. 537 

solutions yield a yellowish white precipitate with chloroplantic 
acid. It is not official. It is also contained in Pituri, a 
drug ' ' chewed by the natives of some parts of Australia as a 
stimulant narcotic," though, according to Liversedge, the latter 
alkaloid may have the formula C^2l^i6-'^2- 

Pelletierine. — Pelletierine tannate [Pelletierince. Taimas, 
U. S. P.), is the name given to the mixture of the tannates of 
punicine, iso-punicine, methyl-punicine and pseudo-punicine, 
obtained from Fwiica Granatum [Granatuin, U. S. P.). 

Physostigmine, or ESERINE (from Esere, the name of the ordeal 
poison of the bean at Calabar), C^j^H^gNgO.^.— An alkaloid of melt- 
ing-point 106° C, obtained from the Calabar Bean {Physostigma, 
U. S. P.), the seed of Physostigma venenosum (Jobst and Hesse), 
by dissolving the ethereal extract in water, filtering, adding sodium 
bicarbonate, shaking the mixture with ether, and evaporating the 
ethereal liquid. Extractum Physostigmatis, Tbictura Physostigmatis, 
Physostigmince Salicylas and Physostigmince Sulphas are official. 
A trace of it powerfully contracts the pupil of the eye and is 
applied in the form of disks; a small quantity is highly poisonous. 
Eber states that physostigmine, by action of acids, etc., takes up 
the elements of water and becomes eseridine, CJ5H23N3O3, melting- 
point 132° C, an alkaloid one-sixth the strength of physostigmine 
and occurring to some extent in the Calabar bean itself. Ehren- 
berg finds, also, eseramine, C^^Hg^N^O.^ (melting-point 238° C, 
physiologically inactive), and gets eserolme as a derivative of 
physostigmine. 

Pilocarpine, C^H^^NgOg, is apparently, the active principle 
of the diaphoretic and sialogogue Pilocarpus Jaborandi {Pilocarpus, 
U. S. P.). The occurrence of an alkaloid in this plant was first 
announced by Hardy, followed almost immediately by Byasson. 
A crystalline nitrate and hydrochloride were first obtained by 
Gerrard. The leaves also yield an essential oil, a terpene Cj^H^^ 
(Hardy). Harnack and Meyer state that the formula for pilo- 
carpine is Cj^H^pNgOg, and that its effects resemble those of nico- 
tine; also that jaborandi yields another alkaloid, jaborine, 
C^gHj^N^O^, which is allied to atropine in its effects. Piloca?'- 
pince Hydrochloridnm and Pilocarpince Nitras are official. Pilo- 
carpine has a faintly bitter taste, and is soluble in water and in 
alcohol. Concentrated sulphuric acid forms with it a yellowish 
solution which, on the addition of potassium dichromate, gradu- 
ally acquires an emerald-green color. It leaves no ash when 
burned with free access of air. It causes contraction of the pupil 
of the eye. Merck states that a third alkaloid, pilocarpidi/)e, 
C,oHj^IS'202, is present in jaborandi. Harnack thinks that pilo- 
carpine is probably a methyl derivative of pilocarpidine; ]\Ierck 
has shown that the base to which Harnack gave the name pilo- 
carpidine does not yield pilocarpine by methylization, and that 
the isomer obtained by this operation diflers from pilocarpine in 



538 ORGANIC CHEMISTRY. 

being insoluble in water. Merck, confirmed by Hardy and Cal- 
mels, states that jaborine is derived from pilocarpine by natural 
oxidation, while pilocarpidiue by oxidation yields jaboridine, 
C^^HjgN.^Og. The latter chemists have obtained pilocarpine arti- 
ficially, /3-pyridyl-a-lactic acid being converted into pilocarpidine, 
and this into pilocarpine. 

PiPERiXE, (Piperina, U. S. P.), Cj^H^gNO.,, is a feebly basic 
alkaloid occurring in White, Black {Piper, U. S. P.), and Long 
Pepper [Chavica officinarum, Mign. ), and in Cubeb Pepper {Cubeba, 
U. S. P. ), associated with volatile oil and resin ; to these sub- 
stances the odor, flavor, and acridity are due, Piperine is obtained 
on boiling white pepper with alcohol, and evaporating the liquid 
with solution of potassium hydroxide, which retains the resin. 
Recrystallized from alcohol, piperine forms colorless prisms fusible 
at 212'' F. (100° C). With acids and certain metallic compounds 
it forms salts, and distilled with concentrated alkali yields piperi- 
dine, CjH^^N, an alkaloid of strongly marked properties, and 
piperic acid, C^2HjqO^. Piperidine is interesting as being one of 
the alkaloids that has been obtained artificially by Ladenburg. 
It is hexahydro-pyridine, and is obtained by the hydrogenization 
of pyridine (by the action of sodium in presence of alcohol). 
Johnstone finds it in long pepper and in ordinary pepper, more 
especially in the husk. According to Buchheim the amorphous 
resin of the peppers is similar in constitution to piperine, alkalies 
breaking it up into piperidine and chavicic acid. Pyrethrin is also 
said to decompose in an analogous manner. The piperine of 
cubeb pepper is not to be confounded with cubebin, a neutral con- 
stituent and having the formula C^^HjoOg. Piperidine acid tar- 
trate, a crystalline salt easily soluble in water, is a good solvent 
for uric acid. 

Sanguinarine is the alkaloid of Blood Root {Sanguinaria 
canadensis, Sangui)iaria, U. S. P.). Its salts are red. Konig and 
Tietz find five distinct alkaloids in the root of sanguinaria, viz., 
chelerytfirine, CgjIIj^NO^ ; sanguinarine, CjoH^-NO^ ; a-hornocheli- 
donine, 02^112^X05 ; li-homochelidonine, Oj^HjiNOj ; and protopine, 
CgoHj.NOj. Protopine was found in opium by Hesse. It also 
occurs in Celandine (Chelidonium, U. S. P.), and is identical with 
macleyine obtained by Eyckmann from Macleya cordata. 

Scopolamine. — See Hyoscine. 

SoLANiXE. — This alkaloid exists in the Woody Nightshade, or 
Bitter-sweet {Solanum dulcamara). It occurs also in the shoots, 
and in minute amount in the skins, of the tubers of the Potato 
(Solanum tuberosum). This alkaloid is only slightly soluble in 
water, alcohol, or ether; nitric acid colors it yellow; sulphuric 
acid produces at first a yellow, then a violet, and finally a brown 
coloration. By the action of dilute acids it is easily converted 
into a sugar and solanidine. Geissler finds dulcamarin, C22H3^0,o, 
a glucoside, to be the bitter constituent of Solanum dulcamara. 



ALKALOIDS. 



539 



Sulphuric acid and alcohol, or either selenic acid or sodium sele- 
nate aud sulphuric acid, colors solanine or solanidine a dark red. 

Sparteine, C^jR^gNg, is a poisonous volatile alkaloid occurring 
in Broom-tops {Scoparius, U. S. P.). Its discoverer, Stenhouse, 
considers that the diuretic principle of broom is Scoparin, O^^^^^O^^, 
a non-poisonous substance, sparingly soluble in cold water. Mills 
has obtained ethyl sparteine, Q^JA^X^.^B..^^, and diethyl-sparteine 
C^5H2^(C2H-)2N2. Apparently sparteine contains two pyridine 
nuclei. Sparteince Sulphas, U. S. P., has the formula C,,H,„N„ 
H2SO„5H20. 

Stillingine. — Bichy states that this alkaloid is present in 
Stillingia sylvatica or Queen's Root, [Stillingia, U. S. P.). 

Taxine, C^^HggNOjo ? is an alkaloid occurring in the yew. 

Theine.— /S'ee Caffeine. 

Theobromine, C^HgN^Og, is an alkaloid occurring in cocoa, the 
seed of Theobroma Cacao, to the extent of 1 to 2 percent. Accord- 
ing to Schmidt, some caffeine is present also. Theobromine is also 
in Kola-nut (Heckel and Schlagdenhauffen). The caffeine in 
cacao, kola, and tea, is said to occur normally as a glucoside, 
which would explain why it is only partially extracted by chloro- 
form from a mixture either of these substances with lime. 

Relations between Caffeine and Theobromine. — Both caffeine and 
theobromine are methyl derivatives of xanthine, C.H^N^Og (belong- 
ing to the uric acid group, uric acid having the formula C-H4]Sr^0.^). 
Caffeine, or trimethyl xanthine has been obtained synthetically 
from uric acid by Fischer and Ach. Theobromine, or dimethyl- 
xanthine may be obtained from a silver derivative of xanthine by 
the action of methyl iodide; and caffeine (methyltheobromine) 
may be obtained by heating theobromine silver with methyl iodide 
(Strecker). Theophyllin, isomeric with theobromine, was obtained 
by Kossel from tea extract. 






HN— CO 

I I 
OC C— NH 

HN— C— NH 

Uric acid 



HN— CH 

I II 
OC C— NH 

I I /^^ 
HN— C=N 
Xanthine 



CH3N— CH 

'I II 
OC C— NH 

I I /^^ 
CH,N— C=N 

Theobromine or dimethylxanlhine 



CH3N— CH 

I II 
OC C— NCH 



3 
CO 



CH,N 



:N 



Caffeine or trimethylxanthine 



540 ORGANIC CHEMISTRY. 

Trigonelline, C^H^NO,, H^.— Jahns states that this alka- 
loid, as well as one identical with choline, are present in the seeds 
of fcenugreek ov fenugreek [Trigonella Fcenumgrceciun) much used 
in veterinary medicine, and in some varieties of cattle food and 
curry powder, 

Tropine. — See Atropine. 

Tylophorine. — See Emetine. 

Vasicine, occurring as adhatodate, has been shown by Hooper 
to be the active principle of the leaves of Adhatoda vasica, or Rus 
(Hind.) or Bakas (Beng.) or Vasaka (Sanskrit), an official Indian 
expectorant [Adhatoda, B. P. Add. 1900). 

Veratrine, or Veratria, [Veratrina, U. S. P.), Cg^H^gNOu. 
— This alkaloid occurs in Cevadilla, the seeds of Schoinocaulon 
officinale, of A. Gray (termed Asagrcea officinalis by Lindley), and 
Veratrum officinale by Schlecht. It is also said to occur in the leaves 
of Sarracenia purpurea. According to Weigelin, cevadilla con- 
tains two isomeric varieties of veratrine, the one soluble the other 
insoluble in water. He says there are also present sabadilline and 
mbatrine. Commercial veratrine contains the two latter alkaloids 
(Weigelin). A mere trace of veratrine brought into contact with the 
mucous membrane of the nose causes violent tits of sneezing. 
These alkaloids, and those from the different species of Veratrum, 
are evidently very closely allied. Wright and Luff, by the use of 
tartaric acid, a solvent less likely than the stronger acids to decom- 
pose alkaloids, extract from cevadilla, veratrine, C;,.H.3N0,^,- 
cevadine, CggH^gNOy; and cevadilline, C.^^^^O^. According to 
Merck, cevadilla contains two alkaloids, sabadine CggH.^NOg, and 
sabadinine, Cj-H^^NOg. 

The alkaloid may be extracted by exhausting the disinte- 
grated cevadilla-seeds with alcohol recovering most of the alcohol 
by distillation, pouring the residue into water, by which much 
resin is precipitated, filtering, and precipitating the veratrine 
from the aqueous solution by addition of ammonia. It is puri- 
fied by washing with water, solution in dilute hydrochloric 
acid, decolorization of the liquid by animal charcoal, reprecipita- 
tion by ammonia, washing and drying. Bosetti states that it is a 
mixture of crystalline cevadine, insoluble in water, with an 
amorphous isomeric soluble alkaloid, veratridine. According to 
Lissauer their physiological action is identical. 

Oleatum Veratrince and Unguentum Veratrince are official. 



1. TAfr'- 

To face page 540. \ 

Dissolve a grain or so in ?"'C iodide and potassium 
iodide) or of bismuth and pot' 

A precipitate indicates thl 

No precipitate indicates ti 



To a small quantity on | 
a porcelain plate add \ 
strong nitric acid. 



To another portion add 
strong sulphuric acid. 



Pujand chloroform. 

Bio 

Orj^ 



Dir 
pjvhich 

Blu 
Bio 



gives a reddish- 



If not found by pre 
ceding sections, heat )- Ee( 
a little in a dry tube. 

If not found by aid of th 
1st. If an alkaloid : ( 

Aconitine . . . Make a diluj 
Atropine ) f Alcoholic so 
Homatropine J [ Add nitric $ 
Caffeine .... Murexid tes 
Cocaine .... Permangan.^nd cooled— crystalline 

precipil. , , . ._, . 
Physostigmiue . Warmed wif^ssolved m acid gives a 
dichroij 
See page 54^ 
Sulphuric aj 



blue fluorescence. 



Pilocarpine . 
Strychnine . 

2d. If not an alkaloid : I 
Acetanilide . . . Heat with \ 
Elaterin .... With phend 
Gluside (saccharin). Is extre 
Jalapin (purified jalap resin), p 
Naphthol . . . Soluble in b " 
Phenacetin . . . Boil with h 
Phenazone (antipyrine, analg 
Picrotoxin . . Compare a 1 . 

Salol . Almost inso'de = violet color. 

Santonin .... Almost insc^ sulphuric acid gives a 

red or i 
Sulphonal . . . Heat with f P ^^d (FciGCNS). 

Note. — Acids are sought 1 

Caution.— A-aj experimerf extremely dilute solu- 
tions to begin with— say 1 dr-^<l"ced in an hour, it is 
easy then to make the experi.^nd so on. The chief 
dilating agents (mydriatics) afgmine and pilocarpine. 



1st. If an alkaloid : 
Beberine .... Very bittei 
2d. If not an alkaloid : 

Aloin Very bittei^'ifl^ addition of a few 

drops (f P claret 011 addition of 
ammoil 
Scarcely sofol^i'- 
See above ( 
Soluble in i^t'y bitter. 
See above (! 



Chrysarobin 
Jalap resin . 
Podophylliu 
Santonin . . 



.,, ^- ''^'"'''^ ™ ^'"^ '^ ^«^ IDENTIFICATION OP OFFICIAL ALKALOIDS, GLUCOSIDES, ETC 

To face page 5i0. {Compiled by F. W Short.) 

Dissolve a gram or so in a few drops of water or dilute hydrochlorir arirl nnH nrlrl n rim,. „<■ at , , .- 
iodide) or of bismuth and potassium iodide. yarocniouc acid, and add a diop of Mayer's solution (mercuric iodide and potassium 

A precipitate indicates the presence of an alkaloid. 

No precipitate indicates the absence of an alkaloid. Search must then be made for glucosides, etc. 



f Purple-red color. 
To a small quantity on | Blood-red " 
a porcelain plate add -I Orange-red " 
strong nitric acid. 



A. If the substance is colorless, or nearly so, then- 



To another portion add 
strong sulphuric acid. 



Dirty-red ' ' 

Red or brown on 
plate, deep red if 
warmed in tube. 

Bluish tinge. 

Blood-red color. 



Apomorphine 

Brucine. 

Morphine, 

Codeine. 

Veratrine, 

Veratrine, 



If not found by pre- 
ceding sections, heat 
a little in a dry tube. 



Bed vapors. 



Confirm by ferric chloride and by sodium bicarbonate and chloroform 
addition of stannous chloride. 

" " ferric chloride and other tests. 

" " sulphuric acid and ferric chloride. 
See next section. 

^"puSecolSr*^''^ ^'^^ '*™"^ liydrochloric acid, which gives a reddish- 
See previous section. 
Confirm by oxidation. 

" " thalleioquin, etc. 



ether test, etc. 



Codeine. 

Salicin (glucoside). 
f Quinine. 
Quinidiue. 
Cinchonine. 
Cinchonidine. 

If not found by aid of the preceding sections, test specially as follows : 
1st. If an alkaloid : 
Aconitine . . . Make a dilute solution and place a drop on the tongue— numbing and tingling. 
Atropine | f Alcoholic sol. added to alcoholic sol. of mercuric chloride and warmed == red pl-ecipitate. 
Homatropine J [ Add nitric acid, dry over water-bath, add alcoholic potash = yellow. 
Caffeine .... Murexid test. 
Cocaine .... Permanganate— purple precipitate. Boiled with potash, then sligliihj acidified with hydrochloric acid and cooled-crvstalline 

precipitate (of benzoic acid). " • 

Physostigmiue . Warmed with potash gives red color, which becomes bluish on evaporation to dryness; the residue dissolved in acid "ives a 

dichroic solution. "^ 

Pilocarpine . . . See page 540. 
Strychnine . . . Sulphuric acid and red potassium chromate. 

2d. If not an alkaloid : 
Acetauilide . . . Heat with potash and chloroform = unpleasant odor of phenyl-isonitrile or phenyl-carbamine, CoHsNC. 
Elaterin .... With phenol and strong sulphuric acid, a crimson color, changing to scarlet. 
Gluside (saccharin). Is extremely sweet. 

Jalapin (purified jalap resin). Insoluble in water or turpentine ; soluble in alkalies or alcohol, partly in ether. Acrid taste. 
N'aphthol . . . Soluble in boiling water, alcohol, ether, and chloroform. Add ammonia to hot saturated aqueous solution = blue fluorescence. 
Phenacetin . . . Boil with hydrochloric acid, dilute, cool, filter, add red chromate = deep red. 

Phenazoiie (antipyrine, analgesin). To an aqueous solution add sodium nitrite and diluted sulphuric acid = deep green. 
Picrotoxin . . Compare a microscopic slide with one of picrotoxin similarly prepared. 

Salol . . , . . Almost insoluble in water, soluble in alcohol, ether, and chloroform. Dissolve in alcohol, add ferric chloride = violet color. 
Santonin . . . . Almost insoluble in water, but soluble in alkalies. Dilute ferric chloride with an equal volume of strong sulphuric acid gives a 

red or violet color. 
Snlphonal . . . Heat with potassium cyanide (odor of mercaptan) ; add water, hydrochloric acid, and ferric chloride = deep red (Fe^GCNS). 
Note. — Acids are sought by the ordinary reactions carefully applied on small quantities of the substance. 

Caution. — Any experiments in which contraction or dilatation of the pupil of the eye is involved should be made with extremely dilute solu- 
tions to begin with — say 1 drop of the solution of the substance under examin^-tion to 1 pint of water. If no effect is produced in an hour, it is 
easy then to make the experiment with a fluid of double this strength, afterward with one of twice the latter strength, and so on. The chief 
dilating agents (mydriatics) are atropine, its isomers and homologues, and the chief contracting agents (myotics) are physost.gmine and pilocarpine. 



B. If the substance is colored, seek the aid of the following memoranda: 
1st. If an alkaloid : 
Beberiue . . . . Very bitter ; soda gives a yellow precipitate, soluble in ether. 
2(1. If not an alkaloid : 

Aloiii Very bitter; nitric ^cid gives a red color (with socaloin brownish). Dissolved in strong sulphuric acid, with addition of a few 

drops of nitric acid, and diluted with water, it gives an orange or red color, which is changed to deep claret on addition of 
ammonia in excess. 
Chrysarobin . . Scarcely soluble in water, soluble in alkalies with fine red color. Strong sulphuric acid gives red-brown color. 
Jalap resin . . . See above (may be almost white). 

Podophvllin . . Soluble in alcohol and precipitated by water. Soluble in ammonia and precipitated by acids. Taste slightly bitter. 
Santonin .... See above (white when fresh, but yellow after exposure to light). 



I 



. f Ammonium (often as 
^ I a contamiuation). 
aj ^ Fekric Salt. 
^ Potassium. 
i Sodium. 



immonium. — Boil aqueous 

ution of scale with potash 

^i test vapor for ammonia. 

^ter and dissolve precipi- 

sfe in hydrochloric acid, 

Jl test the solution for 

n by ferrocyanide, thio- 

iinate, etc. 

"r^otassium and Sodium. — 
—lite a small quantity of 
• scale, and moisten the 
oidue with water. Test 
tistened residue with lit- 
xis-paper. If alkaline, ex- 
i ine for potassium and 
tium by the color im- 
iQ'ted to flame, and for 
assium by the platinum 



Y acidified potash filtrate 
able quantity of ammo- 
precipitated completely 
)ut ten minutes. To the 
t) add three volumes of 
I 3cipitated. If sulphates 
I ate with the alcohol. 



pl/ed hy A. Senier. 



To /■'«■'' /'"^^ ■'^^'^■ 



2. Table for the Qualit 



. , OP Ordtnaky Scale (jompoundh. 



ALKALOIDS. 



Quinine. 

(iUINiniNE. 

Beberine. 



CiNCHONINE. 
('lN(MIONIl)INE. 

Stkychnine. 



Dissolve a l"ii-(i(in in wiitcr, and add aiiunoiii 
alkaloitls (except stryclnnuD and sonn-t inu'S i\ 
mixture u'ith a little ether, and srpa>a(r, U uw: 
solution, aqueous solution, and insoluble 



■antioiisly. Preciintate = 
s fenio liydro.xidc. Agitate the 
means of a pipette, the etlicreai 
■uipitate. 



Ethereal Solution. 



May contain quinine, quinidine, 
or beberine. To solnti.m in a test- 
tube add water very slightly acid- 
ulated with acetic acid, boil, )iurn- 
ing off the ether. To a portion of 
the acetic solution add chlorine- or 
bromine-water, then ammonia. 



Geeen Color 
(thalleioquin). 



Solution is fluor- 

icent, and contains 
either quinine or 
quinidine. Concen- 
trate the remainder 
of the solution and 
divide into two 
parts. To one add 
potassiumiodide,and 
to the other add am- 
monium oxalate. 

The former pre- 
cipitates qidmdme, 
not quinine. The 
latter precipitates 
iimine, not quini- 
dine. 

For other methods 

e page ,524. 



No Green 
Color. 



To a por- 
tion of the 
acetic solu- 
tion add pot- 
ash, a yel- 
lowish-white 
precipitate = 
bcbeyine. 



Insoluble 
Precipitate. 



Is cinchouine, 
einehonidine, or 
ferric hydroxide 
(red). 

Saturate a drop 
or two of acetic 
acid in a little 
water with the 
precipitate, and to 
part of the solu- 
tion add sodium 
tartrate : a precip- 
itate occurs in the 
case of cinchoiii- 
(line, and no pre- 
cipitate in that of 
cinchonine. 



Aqueous 
Solution. 



May contain 
strychnine. Agi- 
tate with chloro- 
form and separate 
chloroformic solu- 
tion. Evaporate 
chloroformic solu- 
tion and moisten 
residue with 
strong sulphuric 
acid. Draw across 
the acid film a 
small crystal of 
potassium bi- 
chromate moist- 
ened with s u 1- 
phuric acid, when 
a transient play 
of colors — violet 
to red = strychnine. 
No color s = no 
strychnine. In 
case of doubt add 
ammonia to orig- 
inal solution, agi- 
tate with chloro- 
form, and proceed 
as before. 



uoi'irosPHORic. 
JIVIOPHOSPHOROUS (generally converted into pyropho.sphoric). 

SOLPHUKIC. 

IJyDRQCin.oRic (as a contamination). 
Tak'i AKic;. 

CiTKK. 



Ignite a small quantity of the scale. Heat the ash with nitric 
acid, and add to it an excess of solution of ammonium molybdate in 
nitric acid, and boil. 



A -Yellow Precipitate. 



Pyrophosphoric or hypo- 
phosphorous acid. Precipi- 
tate some of the aqueous 
solution with potash, filter, 
neutralize with nitric acid, 
and add silver nitrate. 



White pre- 
cipitate solu- 
ble in nitric 
a c i d = j).)/ro- 
pli us Jill ric 
acid. 



White to 
black precip- 
itate solu- 
ble in nitric 
a c i d = hypo- 
phosphorous 
acid. 



No Yellow Precipitate. 



Precipitate some of the aqueous 
solution with potash, filter, and add 
to a portion of the filtrate a slight 
excess of nitric acid, divide into two 
parts. To one add barium chloride 
(ppt. = sulphuric acid). To the other 
add silver nitrate (ppt. = hydrochloric 
acid). Neutralize another portion of 
the potash filtrate with nitric acid 
and add silver nitrate. 



Precipitate 
Gray to Black. 



Add very little 
ammonia (not suf- 
ficient to dissolve 
the whole precip- 
itate) and heat. 
A silver mirror = 
tartaric acid. 

Calcium chlo- 
ride and lime ppt. 
a neutral solution 
(if concentrated) 
in the cold, the 
precip. redissolv- 
ing on boiling. 



Precipitate 
White. 



Citric acid gives 
imperfect or no 
mirror. Calcium 
chloride and lime 
do not precipitate 
citric acid in the 
cold, but upon 
boiling (if solu- 
tion be sufficient- 
ly concentrated) 
precipitation oc- 
curs. 



CM 



Ammonium (often a« 

a contamination). 
Ff:KRic Salt. 
p0ta.h.sium. 
Sodium. 



Ammonium. — Boil aqueons 
solution of scale with jiotash 
and test vapor for ammonia. 
Filter and di.ssoIve precipi- 
tate in hydrochloric acid, 
and test the solution for 
iron by feiTocyauide, thio- 
cyanate, etc. 

Potassium and Sodium. — 
Ignite a small quantity of 
the .scale, and moisten the 
residue with water. Test 
moistened residue with lit- 
mus-paper. If alkaline, ex- 
amine for potassium and 
sodium by the color im- 
parted to flame, and for 
potassium by the platinum 
test. 



Confirm Tartaric or Citric Acid. — To slight! 5^ acidified potash filtrate 
add ammonia in slight excess and considerable quantity of ammo- 
nium and calcium chlorides. Tartrates are precipitated completely 
in the cold with agitation and rest for about ten minutes. To the 
solution (or filtrate, if tartrates are present) add three volumes of 
alcohol (90 per cent.), when ci^mies are precipitated. If sulphates 
liaye been found, disregard a slight precipitate with the alcohol. 



Compiled hy A. Senier. 



ALKALOIDS. 



541 



^5 
? ^ 



^'d o.o cs3 



2 2 



o a> 



I 53 o 



oj *^ -^ o o ;=; o 

3 ^ -i: 5 c <^ 

X r; C3 J2 ^ rj 

-£ ^^'^'d O O -; 



CD . 
> bo 

• -OS 

'^2 



•p Sh 









1-tg less 

ail ^Iss 

ai^t;-^ -2 2 2 

p:^«csaj q;^cScS 



c <u o 2:^ 
.^ bfl?2 



.5; <D 



0,0; o 



o 












o 

'3 o3 



-2-S 



CU 



O <^ rt 



jj o 

o';> 



^^ 






^P^- 
^ 












3 a; 



PI a 

Oi OJ 



Oa5 
a> o 



u 






5 S ''^ '-' 






St-^^'o OJ 



o o aj 



;p5"^rt 



O) 



i:'5 i^ 






tc oS 
03 'C! 



cS 



a CI 

bDbD 



o'3 oi o '^ 



CO O i. "CS !- 



JO- 






'OO o^?^> 



QJ o oi 

'^Qp:; 



r^ O 

o &> 









.2 2"as.... 

■g.:: >>g 03 o g 

,-1 r-l t^ hi - ■ ' 



.So 
>< 2 



o ^ 



;^ :^p:: 



jqp-^'S'Scu .2 



;0> £ 



542 OEGANJC CHEMISTRY. 

QUESTIONS AND EXERCISES. 

How is acouitiue prepared? — Give the strengths of the official prepara- 
tions of the atropine. — Describe the properties of atropine. — What is tlie 
active principle of stramonium? — Mention official preparations contain- 
ing cocaine and beberine. — Give the characters of beberiue. — In what 
does nectandrine differ from beberine ? — Mention the characteristics of 
conine. — What are the active principles of ipecacuanha? — Name the 
alkaloid of tobacco. — Give the properties of the alkaloid of Calabar bean. 
— What are the sources of piperine? — Whence is caffeine obtained ; what 
is its relation to theobromine? — Describe the preparation of veratrine. — 
State the properties of veratrine. 



Here the student is recommended to qualitatively analyze 
unnamed specimens {previously selected for him) of the free and 
combined organic substances included in the appended Tables 
1 and 2. 



SOME IMPORTANT PROXIMATE CONSTITUENTS OF 
ANIMAL AND VEGETABLE ORGANISMS. 

Peoteid Principles, or Albuminoids. 

Albumin. — Agitate thoroughly, some white of ^^^ with 
water, and strain off the liquid from the flocculent membra- 
nous insoluble matter. The white of a hen's ^gg to lOOCc. 
of water forms the " Albumin Test Solution " of the U. S. P. 

Test. — Heat a portion of this solution of albumin to the boiling- 
point ; the albumin becomes insoluble, separating in clots or 
coagula of characteristic appearance. 

Other Reactions. — Add to small quantities of aqueous solu- 
tion of albumin solutions of mercuric chloride, silver nitrate, 
cupric sulphate, lead acetate, alum, stannic chloride, or any 
of the salts of the heavy metals ; the various salts not only 
coagulate, but form insoluble compounds with, albumin. 
Hence the value of an Qgg as a temporary antidote in cases of 
poisoning by many metallic salts, its administration retarding 
the absorption of the poison until the stomach-pump or other 
means can be applied. Sulphuric, nitric, and hydrochloric 
acids coagulate albumin ; the coagulum is slowly re-dissolved 
by aid of heat, a brown, yellow, or purplish-red color being pro- 
duced. Neither acetic, tartaric, nor organic acids generally, 
except picric and gallotanuic, coagulate albumin. Alkalies 



ANI3IAL SUBSTANCES. 543 

prevent the precipitation of albumin, and hence, in testing for 
albumin when only a trace is suspected to be present, it is 
well to make the fluid very faintly acid with acetic acid. 
Excess of acid acts like alkali in preventing coagulation but 
not so powerfully ; in one case the absence of coagulation is 
due to the formation of acid albumin and in the other to the 
formation of alkali albumin both of which are products formed 
by the partial disintegration of the proteid molecule and com- 
bination of the portions of the disintegrated molecule with the 
alkali or acid. 

The products so formed are soluble even on boiling and 
hence no coagulation occurs when dilute solutions of albumin 
are boiled in presence of excess of alkali or acid. 

Yolk or Yelk of Egg contains 16 percent, of proteid, and 32 per- 
cent, of fatty matter. The greater part of the proteid is in com- 
bination either with nucleins, among which the iron-containing 
nucleo-proteid is of importance as a hsemoglobin producer ; or 
with the phosphorized fats or lecithins, forming lecith-albumins 
or vitellins. 

Albumin is met with in large quantity in the serum of blood, 
in smaller quantity in chyle and lymph, and in the vascular 
tissues generally. It is not a normal constituent of saliva, gastric 
juice, bile, or mucus, but may occur during inflammation. It is 
found in the urine and faeces only in certain diseased states of the 
system. 

Albumin is a highly complex substance, and its formula nnd 
chemical constitution are at present unknown. Egg albumin has 
been shown by direct determinations of osmotic pressure to possess 
in solution a molecular weight of about 10,000, while serum 
albumin has a molecular weight of about 50,000. Solutions of 
albumin, probably on account of the large size of the molecule, 
do not diffuse through parchment paper and in this way may be 
dialyzedfrom admixed crystalloids {i.e., substances which separate 
from solution in crystalline form, as contrasted with colloids, or 
glue-like substances, which do not crystallize). This method of 
separation is often of practical importance in medico-legal anal- 
yses. 

Egg albumin (and, to some extent, blood albumin) is largely 
used by calico-printers as a vehicle for colors, serving also, when 
dry, as a glaze. Curriers prize egg-oil for softening leather. 

Fibrin, Casein, Legumin. 

Fibrin is the substance formed when blood or lymph undergoes 
coagulation. It is produced in the blood in the process of coagii- 



544 ORGANIC CHEMISTRY. 

lation from a very unstable compound termed fibrinogen. The 
fil)nnogen is attacked after the blood is shed by a ferment which 
is formed from the disintegrating white corpuscles. These corpus- 
cles yield a substance which combines with the calcium salts present 
in the fluid, to form a soluble ferment termed fhrombosin or fibrin 
ferment. The thrombosin then acts upon the fibrinogen and con- 
verts it into insoluble fibrin in the form of long threads of substance 
which bind the red corpuscles into a solid clot. Fibrin may be 
obtained by whipping fresh blood with a bundle of twigs, separating 
the adherent fibres, and washing in water until free from red cor- 
puscles. It may best be kept in equal parts of glycerin and water. 

Average Composition of Blood. — In human blood the moist 
corpuscles and plasma make up nearly equal parts; thus A. 
Schmidt found in blood obtained by venesection, 52. 1 parts of 
plasma and 47.9 parts of corpuscles. The plasma contains 
approximately 8 to 10 j)ercent. of coagulable proteids of which 
only about 0.2 to 0.4 percent, is fibrinogen, 3 to 4 percent, globu- 
lin, and 5 to 6 percent, albumin. In addition there are about 
0.6 percent, of other organic constituents, including about 0.15 
percent, of glucose which forms the circulating carbohydrate of 
of the body. The inorganic salts amount to about 0. 8 percent. , 
the salt present in largest amount (0. 6 percent.) is sodium chloride. 

Caseinogen occurs in Cow's Milk to the extent of aijout 4 per- 
cent., dissolved by a trace of salt of an alkali-metal. Its solution 
does not spontaneously coagulate, like that of fibrin, nor by heat 
like albumin; but acids cause its precipitation from milk in the 
form of a curd containing the fat globules (butter) previously 
suspended in the milk, a clear yellow liquid (or whey) remaining. 
Caseinogen, like fibrinogen, is capable of being changed into an 
insoluble form by the action of an unorganized ferment or enzyme. 
The insoluble form is termed casein, and is produced in the manu- 
facture of cheese. The ferment is called renniji, or chi/mosin, and 
is contained in rennet, which is an extract prepared commercially 
from the salted and dried mucous membrane of the fourth stomach 
of the calf, but it is also present in the gastric mucous membrane 
not only of all mammals, but in birds and fishes. Similar milk- 
coagulating enzymes are found in the pancreatic juices, and in 
the juices of the stems and leaves of many plants. As in the case of 
fibrinogen, calcium salts are necessary in order that coagulation 
may occur. 

A rennet extract may be prepared by extracting the salted 
mucous membrane w^ith ten times its volume of a 5 percent, solu- 
tion of sodium chloride (to Avhich 1 part in 10,000 of boric acid 
may be added as a preservative) for about seven days at room 
temperature. The fluid should be stirred up occasionally. Such 
an extract will coagulate 10,000 to 50,000 times its own volume 
of fresh milk. 



V 



MILK. 
Average Composition of 1000 parts of Milk. 



545 



Human 

Cow's 



Specific 
gravity. 



1.030 to 1.034 
1.030 to 1.035 



Water. 


Solid 
constit- 
uents. 


Casein 
and ex- 
tractive. 


Sugar. 


Butter. 


870 


130 


27 


60 


40 


877 


123 


40 


46 


30 



Salts. 

3 

7 



Leeds put the average composition of human milk at 2 percent, 
of proteids, 7 percent, of milk sugar, 4 percent, of fat, and 0.2 
percent, of ash. 

Specific gravity alone, as taken by the form of hydrometer 
termed a lactometer, or even by more delicate means, is of little 
value as an indication of the richness of milk, the butter and the 
other solids exerting an influence in opposite directions. Good 
cow's milk affords from 10 to 12 percent, volume of cream, and 3 
to 3J percent, of butter. The water 6f milk seldom varies more 
than from 87 to §8 percent., and the solid constituents from 13 to 
12. Indeed, excluding its butter, milk is curiously regular in 
composition. The non-fatty solids in the mixed milk of a herd 
or dairy of healthy cows is almost a constant quantity, namely, 
9.3 percent. A lower proportion of non-fatty solids in a sample 
of milk points to the addition of water. Thus, supposing that 
100 grains of a specimen of milk, evaporated to dryness, and all 
butter extracted from the residue (previously disintegrated by help 
of 1 or 2 parts of dried gypsum, or the dried infusorial earth 
termed Kieselguhr) by means of ether, yielded a non-fatty residue 
of 7. 44 grains, the specimen would probably be four-fifths milk and 
one-fifth water. ^ Occasionally, under exceptional circumstances, 
a sample of genuine milk may be somewhat poorer than that from a 
healthy herd. For legal purposes, somewhat varying standards 
have been adopted for different places, about 9 percent, by weight 
of non-fatty solids and 3 percent, of butter-fat being usually re- 
quired. Only in the rare cases of milk containing an unusually 
large proportion of butter-fat could any milk yielding less than 9 
percent, of non-fatty solids be regarded as genuine. And, again, 
no milk would be considered genuine, under such standards, if it 
yielded less than 3 percent, of fat, not even in the rare case of its 
containing an unusually large i>roportion of real non-fatty milk- 
solids. Cows in bad condition might yield milk below those 
standards ; but it could scarcely be considered to be normal, or 
better fitted for food tlian milk watered after leaving the cow. If, 

' Soxhlet detenuincs f;it by noting the specific gravity of an ethereal 
solution and then referring to tables showiugpercentageof fat in ethereal 
solutions of varying specific gravity. 
35 



546 ORGASIC CHEMISTRY. 

therefore, a sample of milk is to be regarded as genuine, a stand- 
ard of 9 percent, of non-fatty solids and 3 percent, of fat caniict 
be regarded as too high. 

When examined under the microscope, milk presents a charac- 
teristic field of minute highly refractive globules consisting of the 
suspended fatty matter, which yields on separation the cream, or, 
when the globules are broken by agitation and coalesced together 
as in churning, the butter. The fat is fluid at the normal temper- 
ature of the animal, and remains so until the milk is well agitated 
by churning or otherwise, or until the milk is frozen. 

Legumin, or vegetable casein, is found in most leguminous seeds, 
and in sweet and bitter almonds. Peas contain about 25 percent, 
of legumin. 

Vegetable albumin is contained in many plant-juices, and is 
deposited in flocculi on heating such liquids. Vegetable fibrin is 
the name given by Liebig and Dumas to that portion of the gluten 
of wheat which is insoluble in alcohol and ether. Sjjongine, the 
organic matter of sponge, ap2)ear to be a proteid. 

The various proteids differ somewhat in their elementary com- 
position, and the results experimentally obtained by different com- 
petent observers even in the case of the same proteid (or, indeed, 
different analyses of the same proteid by the same observer) show 
enough variation to preclude the possibility of deducing empirical 
formulae of any importance. The mean composition of proteids 
is, however, of some physiological importance, esjDecially in the 
case of the nitrogen, a determination of which is often employed 
as a measure of total quantity of proteid, the total nitrogen being 
determined and this multiplied by 6. 25, on the assumption that 
proteid on the average contains 1 6 percent, of nitrogen. The follow- 
ing figures give the limits of variation in each of the elements 
found by different observers : carbon, 50 to 55 percent. ; hydro- 
gen, 6.8 to 7.3 percent. ; nitrogen 15 to 18 percent. ; oxygen, 21 
to 24 percent. ; sulphur, 0. 3 to 2 percent. 

Proteids are found also in combination with other organic groups] 
such as carbohydrates, fats, phosphorized fats, and nucleins, sol 
forming the vast class of compound proteids. Examples are haemo- 
globin, the iron-containing coloring-matter of the blood ; the nu- 
cleins which are proteids combined with carbohydrate-like reducing 
bodies ; the nucleo-proteids which are abundant in cell nuclei and 
are compounds of organic nitrogenous substances (also containing 
phosphorus) called nucleins, with proteids; the lecith-albumins of 
egg-yolk already referred to ; and casein which consists of proteid; 
united to a phosphorus-containing radical. 

Proteids are divided, according to their solubility in water and 
certain saline solutions into " albumens," or "albumins," "globu- 
lins," "albumoses," " jjcptones, " etc. Some globulins and albu- 
moses form most virulent poisons when injected directly into the 
blood stream ; to this class of substances belong the poison of most 



GELATIN-PRODUCING SUBSTANCES. 547 

venomous rejjtiles, and also certain vegetable poisons such as that 
contained in the seeds oi Abi^us precatorius (Jequerity). The albu- 
moses of ordinary digestion are similarly poisonous when injected 
directly into the blood stream. All these poisonous substances 
are, however, harmless when swallowed, being modified as they are 
absorbed from the intestines, and so converted into innocuous pro- 
ducts. 

Musk {Moschus, U. S. P.), ''the dried secretion from the 
preputial follicles of Moschus moschiferus " (the Musk-deer), is a 
mixture of albuminoid, fatty, and other animal matters with a 
volatile odorous substance of unknown composition. ' ' Artificial 
Musk," a synthetical compound having an odor resembling in 
quality and power that of natural musk, is trinitro-tertiary-butyl- 
toluene, CgHCH3(N02)3C(CH3)3. 

Gelatin-producing Substances. 

These nitrogenous substances, collectively known as collagens 
(glue-producing), differ, chemically, from the proteids in contain- 
ing less carbon and sulphur and more nitrogen. They are con- 
tained in certain animal tissues, and on boiling with water yield a 
solution which has the remarkable property of solidifying to a jelly 
on cooling. In the process of boiling with water the collagen 
becomes hydrated and yields the gelatin or glutin which is hence 
called the hydrate of collagen. When gelatin is heated to 130° C. 
the reverse change occurs and collagen is re-formed. The tendons, 
ligaments, bones, skin and serous membranes afford gelatin proper ; 
the cartilage give chondrin, which differs from gelatin in composi- 
tion and in being precipitated by vegetable acids, alum, and lead 
acetate, or subacetate. The purest source of gelatin is isinglass, 
which is the swimming-bladder or sound of various species of yIc/- 
penser, Linn., prepared and cut into shreds. Small quantities 
are more easily disintegrated by a file than a knife. A recently 
prepared 2 percent, aqueous solution forms the Gelatin Test Solu- 
tion, U. S. P. Gelatin {Gelathmm, U. S. P.), is officially defined 
as " the purified air-dried product of the hydrolysis of certain ani- 
mal tissues, as skin, ligaments and bones, by treating w^ith boil- 
ing water." Glue is an impure variety of gelatin, made from the 
trimmings of hides ;^ize is glue of inferior tenacity, prepared from 
the parings of parchment and thin skins. " Among the varieties 
of gelatin derived from different tissues and from the same sources 
at different ages, much diversity exists as to the firmness and other 
characters of the solid formed on the cooling of the solutions. 
The differences between isinglass, size, and glue, in this respect are 
familiarly known, and afford good examples of the varieties called 
weak and strong, or low and high gelatin. The differences are some- 
times ascribed to the quantities of water combined in each case 
with the pure or anhydrous gelatin, part of which water seems to 



548 ORGANIC CHE3IISTRY. 

be intimately united with the gelatin ; for no artificial addition of 
water to glue would give it the character of size, nor would any 
abstraction of water from isinglass or size convert it into the hard 
dry substance of g1 ue. But such a change is effected in the gradual 
process of nutrition of the tissues ; for, as a general rule, the tis- 
sues of an old animal yield a much firmer or stronger jelly than 
the corresponding parts of a young animal of the same species." 
(Kirke's Physiology.) 

Gelatin is precipitated from aqueous solution by alcohol, mer- 
curic chloride, chloroplatinic acid, tannic acid, and many of the 
usual proteid precipitants. Pure glutin or gelatin does not give 
Millon's reaction, that is, a white precipitate turning red on 
boiling, when treated with the mixed nitrates of mercury (Millon' s 
reagent). This reaction is characteristic of all true proteids. The 
failure of this reaction in the case of gelatin indicates the absence 
of the tyrosin group from the gelatin moleule. Aqueous solution 
of gelatin is not, like that of albumin, coagulated by heat, nor is it 
precipitated by acids. By prolonged ebullition its gelatinizing 
power is destroyed. 

Pepsin. 

Pepsin (from TrcTrrw, pepto, I digest) is an enzyme existing in 
the gastric juice, which is secreted by the parietal cells of the 
gastric glands. The hydrochloric acid which accompanies it in 
the gastric secretion is formed by a different type of cell in the 
glands called the oxyntic cells. Pepsin is only active in an acid 
medium. The enzyme exists in the gland cells in a precursory 
form called pepsinogen, and the active pepsin is formed from this 
substance in the act of secretion. 

Pepsin may be prepared in the following manner: — The 
cleansed mucous membrane of the stomach (of the hog, sheep, or 
calf, killed fasting) is scraped, and the scrapings are macerated in 
cold water for twelve hours; the pepsin in the strained liquid is 
then precipitated by lead acetate, the deposit washed once or 
twice by decantation, hydrogen sulphide passed through the mix- 
ture of the deposit with a little water to remove the whole of the 
lead, and the filtered liquid evaporated to dryness at a tempera- 
ture not exceeding 105° F. (40.5° C). 

Pepsin {Pepsimim, U. S. P.), is officially described as a proteo- 
lytic ferment or enzyme obtained from the glandular layer of the 
fresh stomach of the hog and proved to be capable of digesting 
not less than 3000 times its own weight of freshly coagulated and 
disintegrated egg albumin. 

It is obtained as ' 'lustrous white, pale yellow or yellowish, 
transparent or translucent scales or grains, or a fine white or 
cream-colored powder, free from any offensive odor, and having a 



BILE. 549 

slightly acid or saline taste. It should be not more than slightly 
hygenopic. ' ' The official assay of pepsin is based on the capacity 
of the preparation for digesting coagulated egg albumin. 

The solvent action of pepsin and hydrochloric acid on proteids, 
leads to the formation of a complex mixture of acid albumin, 
albumoses, and peptones. 

The albumoses are an intermediate stage in the conversion of 
coagulable proteid into peptones. 

The product obtained by the artificial action of pepsin on 
various forms of proteid is known commercially as peptone. 

Any form of proteid may be digested as above described with 
pepsin and hydrochloric acid, and various commercial peptones 
are so prepared from white of egg, minced meat, or blood fibrin. 
Papain is a proteolytic enzyme contained in the leaves of the 
papaw tree ( Carica papaya) which has been utilized as an arti- 
ficial digestive agent for proteids. 

Pancreatic Enzymes. 

The pancreas (sweetbread) secretes a colorless fluid of alkaline 
reaction which contains enzymes acting respectively upon each of 
the three classes of foodstuflfs, viz., proteolytic enzyme called 
trypsin which converts proteids into albumoses and peptones in 
neutral or alkaline solution; an amylolytic enzyme called amylopsin 
or pancreatic diastase which converts starches into dextrins and 
maltose; and steatolytic or fat-splitting enzyme called steapsin or 
lipase which hydrolyzes fats into fatty acids and glycerin. Active 
extracts may be prepared by extracting the gland, which ought to 
be allowed to stand for some hours before extraction, with water 
faintly acidulated with acetic acid, with dilute alcohol (1 in 4), 
with equal parts of glycerin and water, or with lime water and 
glycerin. The official pancreatin {Pancreatinum, U. S. P.), is 
a cream-colored amorphous powder, usually obtained from the 
fresh pancreas of the hog or the ox. Besides the three enzymes 
named above it contains a fourth enzyme, myopsin. 

Ferratin is an organic iron compound which has been isolated 
from pigs' liver, and is regarded as a normal constituent of the 
organs of the animal body, in the tissues of which it is stored up 
as a reserve material for the formation of blood. 



Bile. 

The gall or bile, (Pel Bovis, U. S. P.), of the ox [Bos tai/rus, 
Linn.), evaporated to one-third of its bulk and freed from mucus 
by agitating with an equal volume of alcohol in which mucus is 
insoluble, setting aside for three or four days, filtering and eva}^- 
orating, yields the official Purified Oxgall {Pel Bovis Puri^ficatinn, 



I 



550 ORGANIC CHEMISTRY. 

U. S. p.): the latter has the appearance of a yellowish-green soft 
resin, but is chiefly composed of two crystalline substances; the 
one is termed sodium faurocholate, NaCjgH^^NO^S, the other is 
sodium ghjcocJioktte, ^aC^^^^O^. Both taurocholates and glyco- 
cholates readily undergo hydrolysis, the former yielding eAo//c or 
cholalic acid, ^ILC.^^ll.^Jd.J and taurine, Q.^YL^IsOp, the latter 
cholalic acid and glycine, gbjcocoU, or aniido-acetic acid, 
CH2(NH2)COOH, a soluble crystalline substance having interesting 
physiological relations, for it is obtainable from gelatin (hence the 
name glycocoll or sugar of gelatin, from y7.vKVQ, gluciis, sweet, and 
K.671a, kolla, glue) and from hippuric acid. 

Choline (xo>'), chole, bile), C^H^-XO^, is an alkaloid originally 
found in bile, where it is derived from decomposition of lecithin, 
but it occurs in the brain, etc., in cod-liver oil, and in plants — 
ergot, Indian hemp, ipecacuanha, etc. 

Tests for Bile. — The presence of bile in a liquid such as 
urine, may be detected by the following test : 

1. The inside of a porcelain capsule is wetted with the 
suspected liquid, one or two crystals of cane-sugar are added, 
and then a few drops of concentrated sulphuric acid. 

The capsule is then gently warmed, care being taken not 
to char the contents, when a reddish coloration develops, 
rapidly changing to violet. This test is known as Pettenkofer's 
test, and depends upon the interaction between furfurol and 
the bile salts. The furfurol is produced by the action of the 
sulphuric acid on the cane-sugar. 

2. Gmelin's test is given by the bile pigments, and is car- 
ried out by pouring the bile- containing fluid upon fuming 
nitric acid in a test-tube, when colored rings form at the 
junction of the two fluids, a green ring forming above, which 
lower down passes into blue and then into brown near the 
acid. Gmelin's test may also be made by wetting a piece of 
filter-paper with the suspected fluid and then adding a drop 
of fuming nitric acid, which becomes surrounded by colored 
rino;s as described above. 



QUESTIONS AXD EXERCISES. 

In what form is albumin familiar? — Xame the chief tests for albumin? 
Why is the administration of albumin useful in cases of poisoning? — 
Mention the points of difference between yolk and white of ^%%. — From 



COLORING-MATTERS. 551 

wh^t sources other than ejjg may albumin be obtained? — In what respects 

does fibrin difier from albumin? — Enumerate the chief constituents of 

blood. — How may fibrin be obtained from blood ? — State the diifereiice 

between casein, fibrin, and albumin. — What are the relations of cream, 

butter, curds and whey, and cheese, to milk? — Describe the microscopic 

appearance of blood and milk. — How much cream should be obtained from 

good milk? — What is the percentage of water in genuine milk?— Name 

the sources of vegetable albumin and vegetable casein. — Give the per- j m^ j^. 

centage of nitrogen in albuminoid substances. — Describe the chemical i 

nature of musk. — In what lie the peculiarities of gelatin-producing sub- j 

stances? — To what extent do isinglass, glue, and size difier? — Whence 

is pepsin obtained, and how prepared? — Give the proximate constituents 

of bile. — What are the tests for bile ? 



COLORING-MATTERS. 



The animal, vegetable, and mineral kingdoms abound in more 
or less brilliantly colored natural substances which are frequently 
employed as dyes or pigments, while art has richly supplemented 
the number of such natural coloring-matters. In the following 
paragraphs some of the more useful of these materials are enumer- 
ated under their respective colors: 

Yellow. — Chrome yellow occurs in more than a dozen shades 
(.see Lead chromate). 2. Fustic or yellow wood, iYiQ y^oodi oi Rhus 
Cotinus, is colored hj fisetin, its leaves by myricetin (Perkin). 3. 
Gamboge [see p. 479). 4. Ochre is met with of many tints, under 
the names of yelloiv ochre, gold gellow, gold earth or ochre, yelloiu 
siemia, Chinese yellow. It is chiefly a mixture of iron oxyhydrox- 
ides with alumina and lime. It has been used from the earliest 
times. 5. Orpiment and King's yellow are arsenic sulphides. 
6. Persian berries, or Avignon grains, contain a yellow principle 
termed rhamnin and other crystalline bodies; they are the product 
of two or three species of Rharnnus. 7. Purree, piuri or Indian 
yellow, is said to owe its color to a magnesium compound of euxan- 
thin, Cj<,H^^O,j. 8. Quercitron is the bark of Qnercus tlnctorin ; 
it contains the yellow glucoside, quercitron, C^jH^^O^.^. 9. Rhu- 
barb {see Chrysophanic acid). 10. Saffron, the dried stigma and 
part of the style of Crocus sativus, yields polychrolte or crocin, an 
orange-red glucoside. Kayser gives the formula of crocin as 
C^^H^ypOgg, and states that by interaction with Avater (7H,0) it 
yields crocetin, C.^^H^Pg, and glucose (9CgH,,0,,). Any admixture 
of calcium carbonate, barium or cak^ium sulphate, or similar 
powder, with saffron, is readily detected by placing a small sample 
in a glass of warm water and stirring, when insoluble powder is 
deposited. Incinerated with free access of air, dried saflron does 
not deflagrate, and yields about 7 percent, of ash. 11. Turmeric. 
the rhizome of Curcuma, longa, owes its yellow color to curcumiu, 
a substance which crystallizes from alcohol in ])risms. Jackson 
and Menke state that curcumin is an acid, and that its formula is 



552 COLORISG-MA ITERS. 

HgCi^HjjO^. Apparently two yellow pigments are present. The 
coloring-matters of turmeric are readily dissolved by chloroform, 
while those of saffron, mustard, or the best East-Indian rhubarb 
are not. On this fact methods of detecting turmeric in those sub- 
stances have been founded. 12. Weld {Reseda hdeola) contains a 
durable yellow matter termed luteoUa (CgoH^^O^). 13. Picric or 
carbazotic acid (p. 435) is a very powerful yellow dye. 14. Dried 
and powdered carrots yield to carbon bisulphide a yellow coloring- 
matter, "carrotin," which is obtained on evaporating the solvent. 
It is said to be used in coloring butter. 

Red. — 1. Alkanef, the root of Alkanna tinctoria, Tausch, 
Anchusa tinctoria, Desf., yields anchusin or alkannin, Cj.H^^O^, a 
resinoid substance soluble in oils and fat. 2. Annatto, arnatto, or 
arnotto, a paste prepared by evaporating a strained aqueous extract 
of the seeds of Bi.va Orellana, contains bixin, C^gHg^O., an orange- 
red, and orellin, a yellow, principle. 3. Brazil-wood {Ccesalpinia 
Brasiliensis) furnishes brezilin, Cj^H^^Oj, the basis of several 
lakes; sajjpan-ivood contains either brezilin or a closely allied sub- 
stance, sappanin ; Camwood, from Baphia nifida, contains a simi- 
lar substance, perhaps santalin. 4. Cinnabar, Chinese red, Ver- 
milion, or Paris red, is mercuric suljjhide. It is a veiy ancient 
red pigment. 5. Chrome-red is a lead oxychromate. 6. Cochin- 
eal {see p. 323). 7. Madder, the root of Bubia tinctoria, powdered 
and treated with sulphuric acid and acidulated water to effect the 
removal of earthy and other inert matters, furnishes a residual 
powder termed garancin. Garancin yields to pure water alizarin, 
C,^HgO^, the red, neutral, crystallizable coloring-matter of madder. 
Alizarin does not exist ready formed in the plant, but is derived, 
by fermentation, from a glucoside, termed rubianic acid. Alizarin 
is now largely produced artificially from anthracene, one of the 
solid constituents of coal-tar {see p. 411). 8. Mvlberry-juice con- 
tains a violet-red coloring-matter which has not been chemically 
examined. 9. Red lead {see p. 222 j. This, and the following 
red ochre, are very ancient red coloring-matters. 10. Red iron 
oxide, of shades varying from light to brovrn-red, is found native. 
The common names of it are Armenian bole, Berlin red, colcothar, 
English red, red ochre, burnt ochre, red earth, terra di sienna, 
mineral purple, stone-red, and Indian red. 11. Red Saunders 
{Santalum Rubrinn, U. S. P.), or Red sandal-wood or barwood, the 
billets and chips of the heart-wood of Pterocarpiis santalimis, owes 
its color to santalin, C,pH^^O.^, a crystalline substance possessing 
an acid character. Crystalline pterocarpin, Cj^jHgOg, and horno- 
pte7'ocarpin, C^JI^.p^, are also present (Cazeneuve). 12. Red-Popjpy 
Petals from Papaver Rhceas, contain a red coloring principle which 
has not yet been isolated in a state of puritN\ The author has 
sought for morphine in large quantities of the petals, but could 
not find a trace of that alkaloid. 13. Red-Rose Petals {Rosa Gal- 
lica, U. S. P.), and those of the Cabbage-Rose, also yield a red 



BLUE, 



553 



substance which has not been analyzed. 14. Safflower, dyer's 
saffron, or bastard saffron, the florets of Carthamus tinctorius, con- 
tains an unimportant yellow dye, and 5 percent, of cartharnin, 
Cj^HjgO-, an uncrystallizable red dye, the pigment of the o\A pink 
saucers. Cartharnin seems to possess acid characters, and (like 
silicic acid and other substances) to be soluble in water for a cer- 
tain time after liberation from its alkaline solution; for fabrics are 
dyed with safflower by immersion in a bath made of an infusion 
in dilute alkali neutralized by citric acid immediately before use, 
the carthamin probably penetrating the cells and vessels of the 
fibres in a soluble form, there becoming insoluble and imprisoned, 
and thus giving permanent color to the wool, silk, or other mate- 
rial. Mixed with French chalk, carthamin is used as a cosmetic 
under the name of vegetable rouge — carmine being animal rouge, 
and red iron oxide the mineral rouge. 15. Lac-dye is a cheap form 
of cochineal, and is also yielded by the species of Coccus whose 
resinous excretion constitutes lac {stick-lac, seed-lac, or shell-lac, 
according to its condition as gathered off the twigs on which it is 
deposited, or as roughly separated from impurities in seed-like 
powder or lumps, or as melted and squeezed through bags into 
shell-like pieces). 16. Logwood {Hcematoxylon, U. S. P.), con- 
tains a yellow substance, liKmatoxylin, G^^^f)^.,YL.f){oY 3H,p), to 
which any medicinal usefulness of the wood is perhaps due, and 
which, under the influence of air and alkali or ferments, assumes 
a very intense red color — hceniate'in. Under the joint influence of 
ammonia and air hsematoxylin yields greenish- violet iridescent 
scales of this hcematein, C^gH^p^, 3H.p. 17. Red enamel colors, 
for glass-staining and ceramic operations, are produced either by 
cuprous silicate or purple of Cassius (p. 199). 

Blue. — Cobalt oxide precipitated in combination or admixture 
with alumina or calcium phosphate forms Thenard' s blue, cobalt- 
blue, Hoffner's blue, and cobaltic ultramarine. 2. Smalt, Saxony 
blue, or King's blue is rough cobalt glass in fine powder (p. 141). 

Copper-blue, mountain-blue, and English or Hambro' blue are 
chiefly copper oxycarbonates. 4. Indigo, C^^H^^N.O^, is a blue 
coloring-matter deposited when infusion of various species of 

Indigofera is exposed to air and slight warmth. Under these cir- 
cumstances, indican, a yellow, transparent, amorphous substance, 
soluble in water, breaks up into indigo, which is insoluble and 
falls as a sediment, and a sugar termed indiglucin. The indigo is 
collected, drained, pressed, and dried. By the action of reducing 
agents indigo is converted into soluble colorless indigogen, reduced 
indigo, or indigo white : 1 part of powdered indigo, 2 of ferrous 
sulphate, 3 of calcium hydroxide, and 200 of water, shaken 
together and set aside in a well-closed bottle, yield this colorless 
indigo, CjpHj^N.p.^. Linen or cotton yarn, or calico, dipped into 
such a solution and exi)osod to air, becomes blue, deposition of 
insoluble indigo-blue occurring within the cells and vessels of the 



5 54 COL RING-MA TTERS. 

fibre. This operation is readily performed on a small scale, and 
forms an illustration of a characteristic feature of the art of dyeing 
— namely, the introduction of soluble coloring-matter into a fabric 
by permeation of the walls of its cellular and vascular tissue, and 
the imprisonment of that coloring-matter within the cells and ves- 
sels by conversion into a solid and insoluble form (.see p. 148), 
Pure indigo, or indiyotin, may be obtained in beautiful needles by 
spreading a paste of indigo and plaster-of-Paris on a tin plate, and 
when quite dry placing a lamp underneath, moving the latter from 
place to place as the indigo sublimes and condenses on the surface 
of the plaster. It may also be obtained in crystals by gently boil- 
ing finely powdered indigo with aniline, filtering while hot, and 
setting aside; these crystals may be washed with alcohol. Hot 
parafiin may be employed instead of aniline. Indigo may be pro- 
duced artificially. Toluene, from coal-tar, was, by Perkin's pro- 
cess, converted into cinnamic acid, this into a uitro-derivative, 
and this again into orthonitrophenylpropiolic acid. From the 
latter, alkali and grape sugar deposited crystalline indigo (Baeyer). 
Other methods have since been devised. 5. Litmus, lichen-blue, 
turnsole, orchil or archil, and cudbear, are products of the action 
of air and alkalies on certain colorless principles, as 07'cin, 
C,.H3(OH).,CH3, derived from different species of lichen — Roccella, 
Variolaria, and Lecanora. 6. Prussian blue (p. 165) and Turn- 
bull'' s blue (p. 164) are met with under the names of Erlangen, 
Louisa, Saxon, Paris, or Berlin blue. 7. Ultramarine, a very old 
blue pigment, formerly obtained from the rare mineral, lapis 
lazuli, is now cheaply made on a large scale by roasting a mixture 
of fine white clay, sodium carbonate, sulphur, and charcoal or 
rosin. Its constitution is not well made out. Acids decompose it, 
hydrogen sulphide escaping. 

Purple. — See Murexid, p. 346. 

Green. — 1. Cupro-arsenical green pigments (p. 184). Most 
of the ancient greens contain copper carbonate. The original 
emerald green was a hydrous chromium oxide, but cupric aceto- 
arsenite is now sold under this name. 2. Chlorophyll, leaf -green, 
or chromule, is the substance to which the leaves of plants owe 
their green color. It is resinoid, soluble in alcohol and ether, 
insoluble in water, and, on decomposition, yields a yellow and a 
blue substance (the phyllocyanin and phylloxanthin of Fremy 
and of Schunck). Recent researches tend to show that the 
chlorophyll obtained from different plants varies in composition. 
3. Sap-green, buckthorn-, vegetable-, or bladder -green, known also 
as Chinese green, or lohas, is obtained by evaporating to dryness 
a mixture of lime and the juice of the berries of buckthorn 
{Rhamnus catharticus). It is soluble in water, slightly soluble in 
alcohol, and insoluble in ether and oils. 4. Green ultramarine is 
made by a process similar to that for blue ultramarine. 5. Mix- 
tures of the blue and yellow pigments and dyes are common sources 



1 



BROWN; BLACK; WHITE; ANILINE. 555 

of green colors. 6. Glass and earthenware are colored green by 
chromic oxide and cupric oxide. 

Brown. — 1. Umber, sienna, or chestnut-brown is found native. 
By the action of heat it is darkened in tint, and is then known as 
burnt umber. It is a mixture of ferric oxide, silica, and alumina. 
2. Sepia is a dried fluid from the inkbag of cuttle-fishes (Sepiada;); 
by its ejection into adjacent water the animal obtains opportunity 
of escape from enemies. Catechu (p. 342) furnishes a brown 
coloring-matter. 

Black. — 1. BlacHead (p. 297), bone-black (p. 297) or ivory- 
black, and lamp-black, the latter a deposited soot from the incom- 
plete combustion of rosin and tar, are varieties of carbon. 2. 
Burnt sugar, or caramel (p. 485). 8. Indian ink is usually a 
dried mixture of fine lamp-black and size or thin glue. 4. Black 
writing ink consists essentially of iron tannates and gallates 
suspended in water containing a little gum in solution. 5. Printer's 
ink is well-boiled linseed or other oil, mixed with good lamp- 
black, vermilion, or other pigment. 6. Black dyes are frequently 
of the same nature as ink. 7. The old ^^pigme?itum nigrum'' of 
black feathers, such as those of the common rook, of dark hair, 
and probably also of the skin of the negro, is, doubtless, the 
black substance which remains undissolved when black feathers 
are digested for some time in dilute sulphuric acid. It is said to 
have the formula CjgH^pN20g (Hodgkinson and Sorby). 

White Pigments. — 1. Chalk or whiting (pp. 112, 117). 2. 
French chalk, steatite, talc {Talcum, U. S. P.), or soapstone, is j| [ 

largely magnesium silicate. 3. Heavy white (p. 109). 4. Pearl- 
white (p. 229). 5. Plaster-of- Paris (p. 112). 6. Starch (p. 487). 
7. White lead or Cremnitz white (p. 223). 8. Zinc white or 
Chinese vjhite (p. 134). 9. *' Constant" i^^i^e is barium tungstate. 
10. T oWet fiake white is bismuth oxy nitrate; artists' flake vjhite is 
a form of dry white lead (p. 223). 11. Tin and zinc oxides and 
calcium phosphate are employed for giving a white opacity to 
glass. 

Aniline Colors. Coal-tar colors. — Within the past few years 
nearly every shade of color seen in the animal and vegetable king- 
doms has been successfully imitated by certain dyes and pigments 
primarily derived from a mineral, coal. Coal distilled for gas 
furnishes tar or gas-tar. Coal-tar contains some aniline; but 
especially it contains a liquid convertible into aniline, namely, 
benzene (C,.Hg), first discovered by Faraday in compressed oil- 
gas. From aniline, by oxidation, Eunge obtained the violet- 
color reaction, the substance producing which Perkin afterward 
studied and isolated, and manufjictured under the name of mauve. 
Aniline-red {fucJisine, magenia or rosanilinc), aniline-yellow, ani- 
line-green, aniline-blue, and, in short, aniline-dyes, lakes, and pig- 
ments of the most varied hue are now connnon articles of trade. 
Their application has revolutionized the art of the dyer and coUn- 



556 GENERAL QUALITATIVE ANALYSIS. 

printer. Certain of these coloring matters, for examples tetra- 
methylthionine hydrochloride, [Methylthioidnce Hydrochloridum, 
U. S. P.], methylene blue, are used in medicine. Some of the 
coal-tar colors are not "aniline" colors, being derived from 
naphthalene, phthalic acid, phenol, etc. 



QUESTIONS AND EXERCISES. 
Mention the chief yellow coloring-matters and describe their chemical 
nature. — What is annatto? — Name the colorific constituent of madder. — 
Can it be made artificially? — State the source of litmus.— Distinguish 
between Prussian blue and TurnbuU's blue ; how are they manufac- 
tured?— How are they affected by acids ?— Describe the chemical nature 
of the coloring principle of leaves.— By what agents is glass colored 
green ?— Whence is sepia obtained ?— Describe the chemistry of black 
ink. — Write a few sentences on aniline colors. 



QUALITATIVE ANALYSIS OF SUBSTANCES 
HAVING UNKNOWN PROPERTIES. 

Substances are presented to the analyst in one of the three 
forms in which all matter exists — namely, solid, liquid, or gaseous; 
and they may contain animal or vegetable as well as mineral 
matter. 

The method of analysis in the case of solid mineral bodies has 
been described on pp. 354 to 362. 

Solid animal or vegetable substances (or mixtures of these with 
mineral bodies) may be indefinite and beyond the grasp of 
chemistry, or definite and quite within the range of proximate 
qualitative organic analysis. The presence of such substances is 
indicated in the preliminary examination of a solid (pp. 354 to 
357) by charring and other characters. If no charring occurs, 
and no volatile liquid is expelled by heat, the absence of such 
matter is indicated. But if organic matter is present, an endeavor 
is made to ascertain its precise character. The analyst's knowl- 
edge of the history of the substance, or the circumstances under 
which it comes into his hands, will probably afford a clue to its 
nature, and enable him to search directly for its proximate con- 
stituents. If no such information is at hand, the action of solvents 
may be employed, as likely to afford indication of the general, if 
not of the precise, nature of the substance. Water, alcohol, ether, 
chloroform, carbon bisulphide, each hot and cold, may in turn be 
agitated with the substance ; each extract may then be filtered, 
a portion of the filtrate evaporated, at first partially, setting the 
product aside for the deposition of crystals, etc., and afterward 
to dryness ; and any deposit or residue may be examined with 
and without the aid of a microscope. Other portions of the fil- 



GENERAL QUALITATIVE ANALYSIS. 557 

trate may be treated with acids, alkalies, and solutions of such 
metallic salts as are commonly used as group-reagents for acid 
radicals (p. 352). The action of alkalies as well as acids, dilute 
and concentrated, hot and cold, may also be tried on the solid 
substance itself, and colors, odors, and, in short, any effect what- 
ever, be duly noted. A portion of the substance should also be 
burnt in an open porcelain crucible until no carbon remains, and 
the ash, if any, be examined ; its amount and nature may afford 
information leading to the identification of the substance. 

The foregoing experiments having been carefully performed, 
and all results entered in the note-book, a little reflection will 
possibly lead to recognition, or may suggest further direct experi- 
ments or confirmatory tests, or will, at least, have pointed to the 
absence of a very large number of possible substances, and thus 
have restricted the area of inquiry to comparatively narrow limits. 
The success attainable in qualitative proximate organic analysis 
by the medical or pharmaceutical student will of course largely 
depend on the thoroughness with which the operator has prose- 
cuted his study of practical chemistry generally; but it will be 
considerably affected also by the extent to which he has cultivated 
the art of observation, and the opportunities he has had of acquiring 
a knowledge of the appearance, uses, and common properties of 
definite cliemical substances, and of articles of food, drink, and 
medicine. The most successful of several good analysts will be the 
one who has most common sense and most experience. 

The pharmaceutical student, who has probably already had 
some years of experience in pharmacy, occupies an unusually 
favorable position for prosecuting the proximate analysis of organic 
and inorganic substances, or, at all events, of that large proportion 
of such substances mef with in the domain of hygiene and phar- 
macy. Many substances he will identify at sight, or by aid of a 
lens, or after applying some simple physical or chemical test. Nor 
should he find much difficulty, after reaching the present point 
of practical study, in deciding whether the solid substance under 
examination belongs to the class of organic acids, organic salts of 
metallic radicals, alkaloids, alkaloidal salts, amylaceous matter, 
gums, saccharine substances, glucosides, albuminoid matters, fats, 
soaps, resins, coloring-matters, etc. For instance, the pharma- 
ceutical student will find less difl[iculty than the general student 
in successfully analyzing a substance occurring in "scales," 
because he has experience of the appearances of compounds 
commonly produced in that form, and because, even if the 
appearance is new to him, he knows what kind of substances 
most readily lend themselves to production in that form. While 
the general student is testing generally, and proceeding cautiously, 
or searching for general information in books of reference, the 
})harmaceutical or medical student has incinerated some of the 
material, noticed whether or not the ash is red (iron) and strongly 



558 GENERAL QUALITATIVE ASALYSIS. 

alkaline (potassium^ treated more of the material with an alkali 
(for ammonium), added excess of ammonia, and examined the 
precipitate (for cinchoniue or quinine) or shaken up the alkaline 
liquid successively with ether and chloroform, and tested the 
residue of these decanted and evaporated solvents (quinine, beber- 
ine, strychnine), and examined the aqueous solution of the 
material, or one of the filtered alkaline liquids, in the usual way 
for acid radicals (citric, tartaric, sulphuric, hypophosphorous). 
Or he has modified his methods to include search for some ''scale 
preparation ' ' which his special knowledge tells him has been 
newly introduced to, or is rare in, pharmacy. 

In the case of liquids, the solvents as well as the dissolved matters 
claim attention. A few drops are evaporated to dryness on plati- 
num foil to ascertain if solid matter of any kind is present; the 
liquid is tested with red and blue litmus-paper, to ascertain if free 
alkalies, free acids, or neither are present; a few drops are heated 
in a test-tube and the odor of any vapor noticed, a piece of glass 
tubing bent to a right angle being, if necessary, adapted to the 
test-tube by means of a cork, and some of the distilled liquid col- 
lected and examined; finally, the usual group-reagents for the 
several metallic and acid radicals are consecutively applied. 

Proceeding in this way, the student who has already had some 
experience in pharmacy, will not be likely to overlook such solvents 
as water, acids, alkalies, alcohol, glycerin, ether, chloroform, ben- 
zene, fixed oils, and essential oils, or to miss the substances which 
these menstrua may hold in solution. He will probably also recog- 
nize such liquids as carbolic acid, formic acid, lactic acid, methyl 
alcohol, aldehyde, aniline, nitrobenzene. He must not, however, 
suppose that he will always be able to qualitatively analyze, say, 
a bottle of medicine so as to ascertain, with certainty, the substance 
from which it has been compounded ; for the various infusions, 
decoctions, tinctures, wines, syrups, liniments, confections, ex- 
tracts, pill- masses, and powders contain vegetable matters many 
of which are at present almost beyond the reach of the analyst. 
Neither the highest skill in analysis nor the largest amount of 
experience concerning the odor, appearance, taste, and uses of 
drugs is sufficient for the certain detection of all these vegetable 
matters. Skill and experience combined, however, will do much : 
and in most cases even so difficult a task as the one just mentioned 
may be accomplished with reasonable success. Obviously, quali- 
tative analysis alone will not enable the operator to produce a 
mixture of substances similar to that analyzed ; to this end recourse 
must be had to quantitative analysis, a subject treated subse- 
quently. 

Natural fluids, as ''Milk" and "Urine," admit of special 
analytical treatment (see pp. 545 and 574). 

Gas-anahjsis i^ a branch of chemical analysis, chiefly of a quanti- 
tative character, concerning which information must be sought in 



CHEMICAL TOXICOLOGY. 559 

other treatises. The analysis of atmospheric air from various 
localities, coal-gas, and the gases produced in many technical 
operations or obtained in chemical researches, involves appliances 
and methods which are scarcely within the sphere of chemistry as 
applied to pharmacy or medicine. Beyond the recognition, there- 
fore, of oxygen, hydrogen, nitrogen, chlorine, carbonic anhydride, 
sulphurous anhydride, nitrous gases, hydrogen sulphide, etc., the 
experimental consideration of the chemistry of gaseous substances 
may be omitted. Their study, however, should not be neglected, 
as existing theoretical conceptions regarding chemical substances 
are largely dependent on the observed physical behavior and 
chemical relationships of gaseous compounds (see pp. 26 to 37; 46 
to 48 ; 51 to 60). 

Spectrum Analysis. — It may be well to state here that the prelim- 
inary and final examinations of minute quantities of solid matter 
may, in certain cases, profitably include their exposure to a temper- 
ature at which they emit light, the flame being physically analyzed 
by means of a spectroscope. The spectroscope consists essentially 
of a prism to decompose a ray of light into its constituent colors, 
with tubes and lenses to collect and transmit the ray or rays to the 
eye of the observer. The material to be examined is placed on 
the end of a platinum wire, which is then brought within the edge 
of the flame of a spirit-lamp or Bunsen burner ; volatilization, 
attended usually in the case of a compound by decomposition, at 
once occurs, and in presence of certain substances the flame is 
tinged with a characteristic hue. When examined by means of 
the spectroscope the various colored flames are found to be due in 
each case to rays of certain definite degrees of refrangibility, the 
latter being indicated by the arrangement of colored '' lines " {i.e., 
images of the slit) present in the spectrum of the substance under 
examination. Sodium compounds, when examined in this way, 
give yellow light only, indicated by a double band of light in a 
position corresponding to a portion of the yellow part of an ordi- 
nary solar spectrum. The potassium spectrum is mainly composed 
of a red and violet band ; lithium gives a crimson, and, at very 
high temperatures, a blue band, and so forth. 
_ Bypassing white light through a colored substance an ''absorp- 
tion spectrum" will be produced which is often characteristic, as 
in the case of blood or chlorophyll, solution of potassium perman- 
ganate, etc- 



CHEMICAL TOXICOLOGY. 

In cases of criminal and accidental poisoning, the substances 
presented to the chemical analyst for examination are usually 



560 CHEMICAL TOXICOLOGY. 

articles of food, medicines, or vomited matters ; or the liver, kid- 
neys, intestines, stomach and contents, removed in course of post- 
mortem examination. In these cases some special operations are 
necessary before the poison can be isolated in a state of sufficient 
purity for the application of the usual tests ; for in most instances 
the large quantity of animal and vegetable, or, in one word, organic 
matter present, prevents or masks the characteristic reactions on 
which the tests are founded. These operations will now be de- 
scribed ^ ; they form the chemical part of the subject of Toxicology 
{ro^tKov, toxicon, poison, and Aoyog, logos, discourse). 

Substances occurring ap]3arently as definite salts or unmixed 
with organic matter need no special treatment. They are analyzed 
by the ordinary methods already given, attention being restricted 
to poisonous compounds. 



EXAMINATION OF AN ORGANIC MIXTURE SUSPECTED TO CON- 
TAIN : — MERCURY, ARSENIC, ANTIMONY, LEAD, COPPER, 
CHROMIUM, OR ZINC ; SULPHURIC, NITRIC, HYDRO- 
CHLORIC, OXALIC, OR HYDROCYANIC ACID ; CAUSTIC 
ALKALIES ; PHOSPHORUS ; STRYCHNINE, MORPHINE, OR 
OTHER POISONOUS ALKALOIDS. 



Preliminary Examin at ion. 

Odor, Appearance, etc. — Smell the mixture, with the view 
of ascertaining the presence or absence of any notable quantity 
of free hydrocyanic acid. Look carefully for any small solid 
particles, such as white arsenic, corrosive sublimate, or verdi- 
gris, and for any appearance which may be regarded as 
abnormal, any character unusual to the coffee, tea, beer, medi- 
cine, vomit, coats of stomach, kidney, liver, or other organ, 
tissue, or solid matter under examination. 

Poisonous Quantity of Acid. — Add to a small portion some 
solution of sodium carbonate, with the view of ascertaining by 
strong effervescence the presence of any large poisonous 
quantity of sulphuric, nitric, or hydrochloric acid '(P- 563). 

Poisonous Quantity of Alkali. — If so excessively alkaline 
as to require the addition of a very large quantity of acid be- 
fore neutralization is effected, a noxious quantity of a corrosive 

1 Materials for these experiments are readily obtained for educational 
pur]ioses by dissolving the poison in infusions of tea or coffee, in porter 
or in water to which some starch mucilage or linseed meal, pieces of bread, 
potato, and fat have been added. 



PEE r IN AVION. 561 

or caustic alk di is f ^e ia or potash, < < ., < 

present is ascertaioed by the usual tests. 

Special Instructions may induce the operator to suspect the 
presence of one particular poison. Direct examination for the. 
latter may then be made, either at once, if the substance has 
an aqueous character, or when filtration or treatment with 
warm hydrochloric or acetic acid has afforded a more or less 
colorless liquid. 

Fluids. — A vomit or the contents of a stomach, if set aside 
in a long narrow vessel (test-glass or ale-glass), or, better, 
exposed on a filter during a night, will often yield a more or 
less limpid portion at the bottom or top of the solid 
matter. This fluid (separated by a pipette or otherwise) will 
sometimes respond to tests without further preparation, and 
always requires less preparatory treatment than a semi-solid 
mixture. If none passes through a filter, a portion often 
collects as a lacuna in the upper part. 

General Procedure. — If the preliminary examination 
does not indicate the method to be pursued, proceed as follows, 
treating a portion (not more than one-fourth) of the mixture 
for the poisonous metals, another for the acids, and a third 
for alkaloids, reserving the remainder for any special experi- 
ments which may suggest themselves. 

Examination for Mercury, Arsenic, Antimony, Lead, 
Cop2:)er, Chromium, Zinc. 

If a liquid, acidulate with hydrochloric acid and boil for a 
short time. If solid or semi-solid, cut up the matter into small 
pieces, add enough water to form a fluid mixture, stir in 10 to 
20 percent, of pure concentrated hydrochloric acid, and boil 
until, from partial aggregation and solution of the solid mat- 
ter, filtration can be effected. 

Heat a portion of the clear liquid with a thin piece of 
bright pure copper or copper gauze, about an inch long and 
a quarter of an inch broad, for about ten to twenty minutes ; 
metallic mercury, arsenic, or antimony will be deposited on 
the copper, darkening it considerably in color. Pour ofl' the 
liquid from the copper, carefully rinse the latter with a little 
cold water, dry the piece of metal by holding it over or near 
a flame (using fingers, not tongs, or it may become sufficiently 
hot for loss of mercury or arsenic to occur by volatilization), 
introduce it into a narrow test-tube or piece of glass tubing 
36 



-'olj CHI <fCOT:OGY. 

closeil at oue end, aiul Loat tl . tube in a flame, 

holdiDg it horizoutally so that tlie upper part of the tube 
may be kept cool, aud partially closing its mouth with the 
.finger to prevent escape of vapor. Under these circumstances 
any mercury will volatilize from the copper and con- 
dense on the cool part of the tube in a ring or patch of 
white sublimate, readily aggregating into visible globules on 
being pressed by the side of a thin glass rod inserted into 
the tube ; arsenic will volatize from the copper, and, uniting 
with oxygen from the air in the tube, will condense on the 
cool part of the glass in a ring or patch of white sublimate of 
arsenic (gray and even darker if much metallic arsenic as 
well as w^hite arsenic be present), not running into globules 
when rubbed, but occurring in small crystals, the character- 
istic octahedral form of which {see p. 178) is readily seen by 
aid of a good hand-lens or the low power of a microscope ; 
antimony volatilizes from the copper if strongly heated, and, 
uniting with oxygen, immediately condenses as a slight white 
deposit of antimonious oxide close to the copper. {See p. 191.) 

Confirmatory Tests. — 1. Nothing short of the production - of 
globules should be accepted as evidence of the presence of 
mercury. It will usually have existed as corrosive sublimate. 
2. To confirm indications of the presence of arsenic, a portion of 
the acid liquid may be subjected to the hydrogen tests (pp. 179-182); 
or the tube containing the white crystalline arsenic may be 
broken, and the part on which the sublimate occurs boiled for some 
time in water, aud the hydrogen sulphide, ammonio-silver 
nitrate, and ammonio-copper sulphate tests (p. 184) applied to 
the aqueous solution. 3. For antimony, a portion of the acid 
liquid must always be introduced into the hydrogen-apparatus 
with the usual precautions. {See p. 191.) 4. Any sulphur 
present may darken the copper, and such stained copper may 
subsequently yield a whitish sublimate of sulphur on the sides 
of the subliming tube; such appearances, therefore, are con- 
sistent with the entire absence of mercury, arsenic, and antimony. 

Note. — Before finally concluding that arsenic is absent from a 
fluid, the latter should be warmed with a little sulphurous acid, and 
the ordinary tests then again applied; for arsenic acid and other 
arsenates are not readily affected by the usual reagents for 
arsenic. 

For lead and copper, pass hydrogen sulphide through the 
clear acidulated liquid for some time, warming the liquid if no 
precipitate is produced, or diluting and partially neutralizing 



MINERAL, OXALIC, AND HYDROCYANIC ACIDS. 563 

the acid by addition of ammonia if much acid has been added. 
Collect on a filter any black precipitate "tliat may have 
formed; wash, dissolve in a few drops of aqua regia, dilute, 
and apply tests, such as ammonia for copper, sulphuric acid 
for lead, or any other of the ordinary reagents (pp. 207, 226). 

Copper may often be at once detected in a small quantity of acid- 
ulated liquid by immersing the point of a penknife or a piece of 
bright iron wire — a deposit of copper, in its characteristic color, 
quickly or slowing appearing, according to the amount present 
(p. 207). 

Chromium and Zinc. — To the acid liquid through which 
hydrogen sulphide has been passed, add excess of ammonia 
(or to the original acid liquid add excess of ammonia, and then 
ammonium hydrosulphide); a precipitate is produced which 
may contain alumina, phosphates, chromium, and zinc. (It 
is usually blackish, from the presence of ferrous sulphide.) 
Collect the precipitate on a filter, wash, dissolve in a little 
hydrochloric acid, add a few drops of nitric acid, boil, pour in 
excess of ammonia, filter, and test the filtrate with ammonium 
hydrosulphide ; a white precipitate indicates zinc. A green 
precipitate would indicate chromium. Chroraates should also 
be sought for (p. 169). 

Examination for Mineral Acids, and for Oxalic and Hydro- 
cyanic Acids. 

To detect hydrochloric, nitric, or sulphuric acid in a liquid 
containing organic matter, dilute with water and apply to 
small portions the usual tests for each acid, disregarding 
iudications of small quantities. (>See pp. 255, 274, 293.) 

Excessive acidity, copious evolution of carbonic anhydride on 
the addition of sodium carbonate, and very strongly marked reac- 
tions on the application of the usual reagents to small portions of 
the fluid presented for analysis, collectively form sufficient evidence 
of the occurrence of a poisonous amount of either of the three 
common mineral acids, but in important cases quantitative analyses 
should be made. Small quantities of the hydrochloric, nitric, 
and sulphuric radicals, occurring as metallic salts or acids, are 
common normal constituents of food; hence the direction to disre- 
gard insignificant indications. If the fluid under examination be 
a vomit or the contents of a stomach, and an antidote has been 
administered, free acid may not be found, but, instead, a large 
amount of the corresponding salt. 



564 CHEMICAL TOXICOLOGY. 

For oxalic acid, filter or strain a portion of the liquid, if 
not already clear, and add solution of lead acetate so long as 
a precipitate is produced ; collect the precipitate, which in any 
ease is only partly lead oxalate, on a filter, wash, transfer it to 
a test-tube or test-glass, add a little water, and pass hydrogen 
sulphide through the mixture for a short time ; any lead oxalate 
is thus converted into insoluble lead sulphide, while oxalic 
acid is set free in the solution. Filter, boil to get rid of 
hydrogen sulphide, and to the clear filtrate apply the usual 
tests for oxalic acid (see p. 303). 

The conteuts of a stomach containing oxalic acid will often be 
of a dark-brown color with a tinge of green (altered blood and 
mucus), and the viscid mixture generally, though slowly, aflfords 
some clear, limpid, almost colorless, liquid by filtration or on 
standing. 

For hydrocyanic acid, the three chief tests may be applied 
at once to the liquid or semi-liquid organic mixture, whether 
it has an odor of hydrocyanic acid or not. First : — Half fill 
a small porcelain crucible with the material, add eight or ten 
drops of concentrated sulphuric acid, stir gently with a glass 
rod, and invert over the mouth of the crucible a watch-glass 
moistened with a small drop of solution of silver nitrate ; a 
white film on the silver solution is probably silver cyanide, 
formed by the action of the gaseous hydrocyanic acid on the 
silver nitrate. Second : — Prepare a small quantity of the 
organic mixture as before, slightly moistening the centre of the 
watch-glass with solution of potassium hydroxide ; here, again, 
the heat generated by the action of the concentrated acid is 
sufficient to volatilize some of the hydrocyanic acid, which, inter- 
acting with the potassium hydroxide, forms potassium cyanide. 
On removing the watch-glass and stirring into it successively 
solution of a ferrous salt, a ferric salt, and hydrochloric acid, 
flocks of Prussian blue are produced if hydrocyanic acid is 
present. Third : — Proceed as before, moistening the watch- 
glass with yellow ammonium hydrosulphide ; after exposure 
to the hydrocyanic acid gas for five to ten minutes, add a drop 
of ammonia water, evaporate to dryness at a low tempera- 
ture, then add a drop of hydrochloric acid and of solution of 
ferric chloride ; a blood-red color, due to ferric thiocyanate, is 
produced if cyanogen is present. 

If the above reactions are not well marked, the organic mixture 
may be carefully and slowly distilled in a small retort, the neck 



STRYCHNINE AND MORPHINE. 565 

of which passes into a bottle and dips beneath the surface of a 
little water at the bottom of the bottle; the reagents may then be 
applied to separate portions of the distillate. 

The examination of organic mixtures for hydrocyanic acid must 
be made Avithout delay, as the poison soon begins to decompose, 
and in a day or two may be destroyed. 

Examination for Phosphorus. 

A paste containing phosphorus is commonly employed for 
destroying vermin. In cases of poisoning, the phosphorus is 
generally in sufficient quantity to be recognized by its charac- 
teristic unpleasant smell. A stomach in which it occurs not 
infrequently exhibits slight luminosity if opened in a dark 
room. When the phosphorus is too small in quantity or too 
much diffused to afford this appearance, a portion of the 
material is placed in a flask, water acidulated with sulphuric 
acid added, a long w^ide glass tube fitted to the neck of the 
flask by a cork, and the mixture gently boiled. If phosphorus 
is present (even 1 part in 2,000,000, according to De Vrij) 
the top of the column of steam as it condenses in the tube 
will appear distinctly phosphorescent when viewed in a dark 
room. From its liability to oxidation, phosphorus cannot be 
detected after much exposure of an organic mixture to air. 

Examination for Strychnine and Morphine. 

Strychnine. — If solid or semi-solid, digest the matter with 
water and about 10 percent, of hydrochloric acid till liquid, 
filter, evaporate to dryness on a water-bath. If the organic 
mixture is already liquid, it is simply acidulated with hydro- 
chloric acid and evaporated to dryness. The acid residue 
is next treated with alcohol as long as anything is dis- 
solved, the filtered tincture evaporated to dryness over the 
water-bath, and the residue digested in water and filtered. 
This slightly acid aqueous solution must now be rendered 
alkaline by addition of ammonia, and well shaken in a 
closed bottle or long tube with about half an ounce of chloro- 
form, and set aside until the chloroform has subsided. The 
chloroform (which contains the strychnine) is then removed 
by means of a pipette, the presence of any aqueous liquid 
being carefully avoided, and evaporated to dryness in a small 
basin over a water-bath, the residue moistened with concen- 
trated sulphuric acid, and the basin kept over the water-bath 



566 CHEMICAL TOXICOLOGY. 

for several hours. (It is highly important that the suljDhiiric 
acid used in this operation should be free from nitrous com- 
pounds. Test the acid, therefore, by adding powdered ferrous 
sulphate, which becomes pink if nitrous compounds are present. 
If these are found, the acid should be purified by strongly 
heating with ammonium sulphate, 70 or 80 grains to a pint.) 
The charred material is exhausted with water, filtered, excess 
of ammonia added, the filtrate shaken with about a quarter 
of an ounce of chloroform, the mixture set aside for the chloro- 
form to separate, and the chloroform again removed. If on 
evaporating a small portion of this chloroform solution to dry- 
ness, adding a drop of sulphuric acid to the residue, and warm- 
ing, any darkening of color or charring takes place, the strych- 
nine is not suificiently pure for chemical detection ; in that 
case the rest of the chloroform must be removed by evapora- 
tion, and the residue redigested in warm sulphuric acid for 
two or three hours. Dilution, neutralization of acid by addi- 
tion of ammonia, and agitation with chloroform is again prac- 
tised, and the residue of a small portion of the chloroform 
solution once more tested with sulphuric acid. If charring 
still occurs, the treatment must be repeated a third time. 
Finally, a part of the chloroform solution is taken up by a 
pipette and drop after drop evaporated on one spot of a porce- 
lain crucible-lid until a fairly distinct dry residue is obtained. 
A drop of sulphuric acid is placed on the spot, another drop 
placed near, a minute fragment of potassium dichromate placed 
in the second drop, and when the acid has become tinged with 
the chromate, one drop drawn across the other ; the character- 
istic evanescent purple color is then seen, if strychnine is 
present. Other tests (.yee p. 524) may be applied to similar 
spots. 

This is Girdwood and Roger's method for the detection of strych- 
nine when mixed with organic matter. It is tedious but trust- 
worthy, and, though apparently complicated, very simple in 
principle, thus — strychnine is soluble in acidulated water or alco- 
hol, or in chloroform, readily removed from an alkaline liquid by 
agitation with chloroform, and not charred or otherwise attacked 
w^hen heated to 212° F. (100° C.) with sulphuric acid : much of 
the organic matter of the food is insoluble in water; of that soluble 
in water, much is insoluble in alcohol; and of that soluble in 
both menstrua, all is charred and destroyed by warm sulphuric 
acid in a shorter or longer time. {See also Stas' s general process, 
p. 568.) 



MORPHINE AND MECONIC ACID. 567 

Morphine and the Meconic Acid with which it is associated 
in Opium. — To the liquid or the semi-liquid mixture, warmed 
for some time with a small quantity of acetic acid, filtered, 
and concentrated if necessary, add solution of lead acetate until 
no further precipitate is produced. Filter and examine the 
precipitate for meconic acid, reserving the filtrate for the 
detection of morphine. 

The Precipitate. — Wash the 2:)recipitate (lead meconate, 
etc.) with water, place it in a test-tube or test-glass with a 
small quantity of water, pass hydrogen sulphide through the 
mixture for a short time, filter, slightly warm in a small basin, 
well stirring to promote removal of excess of the gas, and add 
a drop of neutral solution of ferric chloride ; a red color, due 
to the formation of ferric meconate, is produced if meconic acid 
is present. This color is not destroyed on boiling the liquid 
after the addition of one drop of dilute hydrochloric acid, as 
is the case with ferric acetate, nor is it bleached by solution of 
corrosive sublimate, thus distinguishing it from ferric thio- 
cyanate. It is discharged by hydrochloric acid. 

The Filtrate. — The solution from which meconic acid has 
been removed by adding lead acetate is evaporated to a small 
bulk over a water-bath, excess of potassium carbonate added, 
and evaporation continued to dryness. The residue is then 
treated with alcohol, which dissolves the morphine. The 
alcoholic solution similarly evaporated may leave the mor- 
phine sufiiciently pure for the application of the usual tests 
{see p. 514) to small portions of the residue. If no reaction 
is obtained, add a drop of sulphuric acid and a little water to 
the residue, and shake with ether, in which the morphine 
salt is insoluble. The treatment with ether may be repeated 
until nothing more is removed, the acid aqueous liquid 
saturat^id with potassium carbonate, the mixture evaporated 
to dryness, the residue digested in alcohol, filtered, and por- 
tions of the alcoholic liquid evaporated to obtain spots of mor- 
phine for the application of the ordinary tests. 

If much organic matter is believed to remain in the filtrate 
after the lead acetate treatment, or if a considerable excess 
of lead acetate has been employed, the filtered liquid should 
be subjected to a current of hydrogen sulphide until no more 
lead sulphide is precipitated ; the mixture should then be 
filtered, and the filtrate, with the washings from the lead 
sulphide, evaporated to a small bulk, excess of potassium 
carbonate added, the whole well mixed and agitated with 



568 CHEMICAL TOXICOLOGY. 

twice or thrice its bulk of a mixture of ether aud acetic ether 
(ether aloiie would not dissolve the morphine). On standing, 
the ethereal liquid rises to the surface : it is carefully removed, 
evaporated to dryness, and the residue tested or further puri- 
fied in the manner described in the preceding paragraph. 

The examination for morphine umst be conducted with great 
care, and with as large a quantity of material as can be spared; 
for its isolation from other organic matter is an operation of diffi- 
culty, especially when only a minute proportion of alkaloid is 
present. Fortunately the detection of meconic acid does not 
involve similar difficulties; and as its reactions are quite charac- 
teristic, its presence is held to be strong evidence of the existence 
of opium in an organic mixture. 

Examination for other Foisojious Alkaloids. 

Stas's Process. — Minutely subdivide any solid matter ; to 
this and the liquid portion of the vomit, etc., add about 
twice their weight of alcohol containing sufficient tartaric 
acid distinctly to acidify the mixture. Digest the whole 
in a flask at a temperature of 150° to 160° F. (65.5° to 
71° C.) ; set aside to cool ; filter. The solution, which will 
contain the whole of the alkaloid, should then be evaporated 
nearly to dryness in vacuo, or at all events at a temperature 
not exceeding 100° F. (37.7° C), lest volatile alkaloids 
should be dissipated. The residue is next exhausted with cold 
absolute alcohol ; filtered ; and the filtrate evaporated to dry- 
ness w'ith the precautions already stated. The extract is dis- 
solved in a very small quantity of water, treated with excess 
of powdered sodium or potassium bicarbonate, and well shaken 
with five or six times its volume of pure ether (with perhaps 
a little acetic ether). This ethereal liquid contains the alka- 
loid. Small portions should be evaporated in watch-glasses 
and tasted, or tested physically and chemically, according as 
the knowledge of collateral circumstances by the operator, or 
his experience, or such reactions as are recorded on pp. 526, 
541 may suggest. 

If a volatile alkaloid (conine, nicotine, lobeline, sparteine), 
is indicated, the ethereal solution, which may contain animal 
matter, is removed, agitated with aqueous solution of potas- 
sium hydroxide, decanted, and shaken with dilute sulphuric 
acid. On standing, the aqueous portion, containing the alka- 
loid as acid sulphate, subsides ; the up])er ethereal portion 
containing the animal matter is rejected ; the acid aqueous 



rOTSONOVS ALKALOIDS. 569 

liquid is made alkaline with potassium hydroxide ; ether is 
added, aud the whole well shaken ; the ethereal liquid is 
decanted, evaporated to dryness in vacuo, or at a low tempera- 
ture, and (to get rid of all traces of ammonia) again moistened 
with ether and dried. The residue is now tested for the sus- 
pected alkaloid by taste, smell, and the application of appro- 
priate reagents (pp. 526-541). 

If a non-volatile alkaloid (aconitine, atropine, brucine, col- 
chicine, emetine, hyoscyamiue, physostigmine, solanine, vera- 
trine, as well as morphine, codeine, and strychnine, etc.), is 
indicated, further purify by decanting the ethereal liquid from 
the lower aqueous solution of sodium bicarbonate, reinoving 
the ether by evaporation, digesting the residue in alcohol, 
filtering, evaporating the alcohol, treating the residue with 
dilute sulphuric acid, setting aside for a few hours, filtering, 
concentrating, adding powdered potassium carbonate, and 
finally anhydrous alcohol. The alcoholic liquid, on evapora- 
tion, yields the alkaloid in a fit condition for testing in the 
manner already stated. 

Sonnenschein's Process. — Digest with dilute hydrochloric 
acid, evaporate to the consistence of syrup, dilute, set aside for 
some hours, filter. Add solution of phosphomolybdic acid so 
long as any precipitate is produced, or cloudiness appears ; 
collect the precipitate on a small filter ; wash it with water 
containing phosphomolybdic and nitric acids, and, while still 
moist, place it in a flask. Decompose this compound of phos- 
phomolybdic acid and alkaloid by adding barium hydroxide 
until the stirred mixture is distinctly alkaline. Distil ofi" vola- 
tile alkaloids, condensing and collecting these by help of a 
long tube so bent that the apparatus shall act as a retort, the 
end of the tube being attached to a bulb or a series of bulbs 
containing dilute hydrochloric acid. The acid liquid yields 
on evaporation a residue of hydrochlorides of alkaloids. The 
latter will aflTord characteristic reactions with the tests for the 
suspected alkaloid, and, on being moistened with barium 
hydroxide and warmed, will afi^ord fumes of volatile alkoloids 
the odor of which is usually characteristic. The residue in the 
flask will contain non-volatile alkaloids. It is treated with 
carbonic anhydride to neutralize and precipitate the excess of 
baryta as insoluble barium carbonate; the mixture is evapo- 
rated to dryness over a water-bath ; and the residue digested 
in alcohol. The alcoholic solution evaporated generally yiehls 
the alkaloids in a fit state of testing. 



670 CHEMICAL TOXICOLOGY. 

Reagents for Alkaloids. 

Phosphomolybdic acid forms with ammonium salts, in nitric 
acid solution, a remarkably insoluble compound; and it behaves 
in a similar manner with salts of those compounds which are 
more or less analogous to ammonia — the nitrogenous organic 
bases — consequently forming an excellent reagent for their detec- 
tion. It may be prepared in the following manner : A solution 
of ammonium molybdate is mixed with sodium phosphate, whereby 
a precipitate of ammonium phosphomolybdate is produced; the 
yellow precipitate, having been washed, is diffused through water, 
and heated with sufficient sodium carbonate to dissolve it. The 
solution is then evaporated to dryness, and calcined to drive off 
the ammonia. In case any of the molybdic compound be reduced 
by this operation, the residue must be moistened with nitric acid, 
and again calcined. The dry mass is then dissolved in cold water, 
the solution strongly acidulated with nitric acid, and water added 
until ten parts of the solution contain one of the dry salt. The 
liquid, which is of a golden-yellow color, must be preserved from 
contact with ammoniacal fumes. It precipitates all the alkaloids 
(with the exception of urea) when a mere trace only is present. 
The precipitates are yellow, generally flocculent, insoluble in 
water, alcohol, ether, and dilute mineral acids, with the exception 
of phosphoric acid, Nitric, acetic, and oxalic acids, concentrated 
and boiling, dissolve them. These compounds are decomposed 
by the alkalies, certain metallic oxides, and the alkali-metal salts, 
which separate the alkaloid. To give an idea of the sensitiveness 
of this reagent, it may be stated that 0.000071 gramme of strych- 
nine gives an appreciable precipitate with one cubic centimetre 
of the solution of phosphomolybdic acid. 

Phosphoantimonic and phosphotungstic acids are also precipi- 
tants of alkaloids. Platinum, iridium, palladium, and gold chlo- 
rides are occasionally serviceable. Tannic and picric acids, too, 
may be used, and a solution of iodine and potassium iodide. 

Other special reagents for alkaloids are ' 'Mayer's"; "Nessler's" 
{see p. 616); the double potassium and cadmium iodide; and a 
solution of the double potassium and bismuth iodide. The latter 
is made (by Thresh) by mixing together one ounce of solution of 
bismuth and ammonium citrate (800 grains in one pint), 90 grains of 
potassium iodide, and 90 grains of concentrated hydrochloric acid. 
This orange-colored solution gives a red precipitate with dilute 
cold solutions containing alkaloids. 

Ptomaines {Tzru/ia, a corpse) have already been alluded to as 
including poisonous alkaloids producible from putrefying animal 
matters, even the human body itself, during the ordinary processes 
of decay. They are distinguished, according to Brouardel and 
Boutmy, by a drop or two of a solution of their sulphate convert- 
ing a drop of solution of potassium ferricyanide into ferrocyanide, 



POISONOUS ALKALOIDS. 



571 



the mixture then giving a dark-blue precipitate with ii ibiric diiit. 
Same other substances also, as morphine, possess this converting 
pjwer. 

Tyroto.i'icoa. — This ptomaine (p. 511) may be isolated and tested 
as follows: Prepare an aqueous extract of the cheese, or filter the 
coagulated milk, etc. No heat should be applied, and undue 
exposure to air should be avoided by using stoppered bottles. 
Make the filtered fluid faintly alkaline with sodium carbonate, 
and well shake with half its bulk of ether. Allow the perfectly 
clear separated ethereal solution to evaporate spontaneously; and, 
if necessary, again extract the resulting aqueous residue with water, 
shaking with ether, evaporating as before, and testing the residue 
in two or three ways. A little placed on the tongue and swal- 
lowed will cause more or less of nausea, vomiting, purging, and 
headache. Again, the residue is either characteristically crystal- 
line, or will become so after standing in a vacuum over sulphuric 
acid. Mix two or three drops of sulphuric acid and carbolic acid 
on a white plate, and add a few drops of the aqueous residue just 
mentioned; if an orange-red or purple color results, the presence 
of tyrotoxicon may be suspected, but any nitrate or nitrite present 
may cause a similar color. To some of the aqueous residue add 
an equal volume of a saturated solution of potassium hydroxide; 
the double potassium and diazobenzene hydroxide is then formed 
and appears in six-sided plates, whereas any potassium nitrate 
appears in prisms. This residue may be treated with absolute 
alcohol, filtered, and the filtrate evaporated, when the plates may 
again be observed or the color reaction again obtained with this 
purified product (Vaughan). 



ANTIDOTES.— >See "Antidotes" in the Index. 



QUESTIONS AND EXERCISES. 

In examining food and similar matter for poison, why must not the 
ordinary tests for the poison be at once applied ?— What preliminary 
operations should be performed on a vomit in a case of suspected poison- 
ing?— How would you search for corrosive sublimate in wine?— By what 
series of operations would you satisfy yourself of the presence or absence 
of arsenic in the contents of the stomach ?— Describe the treatment to 
which decoction of coffee should be subjected in testing it for tartar-emetic. 
State how the occurrence of lead in water is demonstrated.— Give a pro- 
cess for the detection of copper in jam —How would you detect zinc in a 
vomit ?— How may the presence of much sulphuric acid in gin be proved ? 
—In testing ale for nitric acid what reactions would von select?— Show 
how you would conclude that a dangerous (piantity of livdrochloric acid 
had been added to cider.— Describe the manipuhitions necessary in test- 



r>12 MORBID URINE. 

lug lor hydrocyanic acid in the contents of a stomach. — By what method 
is oxalic acid discovered in infusion of coffee ? — How is phosphorus 
detected in organic mixtures ? — Give the process by which strychnine is 
isolated from a vomit. — Mention the experiments by which the presence 
of laudanum in porter is demonstrated. — Name the antidotes in cases of 
poisoning by: — a, alkaloids ; 5, antimonials ; c, arsenic ; rf, barium salts ; 
e, copper compounds ; /, hydrochloric acid ; g, hj^drocyanic acid ; h, lead 
salts ; i, corrosive sublimate ; j, nitric acid ; fc, oxalic acid ; /, silver salts ; 
m, oil of vitriol ; n, tin liquors ; o, zinc salts ; p, carbolic acid. 



EXAMINATION OF URINE AND CALCULI 

The various products of the natural and continuous decay of 
animal tissue and the refuse matter of food are eliminated from 
the system chiefly as faeces, urine, and expired air. Air exhaled 
from the lungs carries off from the blood much carbon (about 8 
ozs. in 24 hours) in the form of carbonic anhydride, and some 
aqueous vapor — the latter, together with a small amount of oily 
matter, also escaping by the skin. Directing the breath to a cold 
surface renders moisture evident; and breathing through a tube 
into lime-water demonstrates the presence of a considerable 
quantity of carbonic anhydride. The faeces consist mainly of 
insoluble debris of the food, mucus from the intestines, and resi- 
dues from the biliary and other intestinal secretions, the soluble 
matters and water forming the urine. These excretions vary con- 
siderably, according to the food and general habits of the indi- 
vidual and the external temperature. But in disease the variations 
become excessive ; hence their detection by the medical practi- 
tioner, or by the pharmacist for the medical man, is a matter of 
importance. 

An analysis of faeces or air cannot be made with sufficient ease 
and rapidity to be practically available in medical diagnosis. But 
with regard to urine, certain abnormal substances and abnormal 
quantities of normal constituents may be chemically detected in 
the course of a few minutes by any one having already some 
knowledge of chemical and microscopical manipulation. 

The total amount of urine voided daily under normal conditions 
varies considerably, the chief factors in causing variation being 
the amount of fluid taken into the body, and the temperature of 
the surroundings which causes inverse changes in the quantities 
of water removed by the skin, and in the expired air The aver- 
age daily output may be placed at two to three pints in the adult 
(1000 to 1500 Cc). 

The amount and character of the solid constituents of urine vary 
with the character and quantity of the diet, and the amount of 
muscular work and corresponding tissue changes. The average 
amount of total solids is usually given at 70 grammes per diem, 
of which 40 grammes consi.st of organic matter and 30 grammes 



MORBID URINE. 



blZ 



of inorganic salts. The composition of the solids may be stated 
in round numbers, in grammes, as follows : — urea 33, creatinine 
0.9, uric acid 0.5, hippuric acid 0.4, pigment and other organic 
substances 10, chlorine 7.5, sulphuric acid (SO3) 2, phosphoric acid 
(P2O5) 3, sodium 11, potassium 2.5, calcium, magnesium, and 
ammonium 1.2. 

The urea which is present to a considerable extent in urine, is 
the form in which the most of the waste nitrogen is eliminated 
from the system. Its empirical form is CON^H^. Its structural 

formula may be written, COx -^^tt^. that is, it may be regarded as 

carbamide or as one of the organic bases already referred to, a 
primary diamine, in which the bivalent radical CO occupies the 
place of Hg. The other atoms of hydrogen may be displaced by 
various radicals, and many compound ureas thus be obtained. 

Artificial Urea. — Urea may be prepared artificially by William's 
modification of Wohler' s method. Potassium cyanide, of the best 
commercial quality (containing about 90 percent, of real cyanide), 
is fiised at a very low red heat in a shallow iron vessel ; red lead 
is added in small quantities at a time, the temperature being kept 
down by constant stirring. When the red lead no longer produces 
action, the mixture (potassium cyanate and lead) is allowed to 
cool, the product finely powdered, exhausted with cold water, 
barium nitrate added till no more precipitate (barium carbonate) 
is formed, the mixture filtered, and the filtrate treated with lead 
nitrate so long as lead cyanate is precipitated. The latter is 
thoroughly washed, and dried at a low temperature. Equivalent 
quantities of lead cyanate and ammonium sulphate digested in a 
small quantity of water at a gentle heat [see p. 324 ) and filtered, 
yield a solution from which urea crystallizes on cooling. 

Another process. — Basaroflf has found that urea is produced when 
ordinary ammonium carbonate is heated in strong hermetically 
sealed tubes to about 275° F. (135° C.) for a few hours. The same 
chemist had previously obtained urea by similarly heating pure 
ammonium carbamate ; so that the source of the urea in the former 
case is probably the ammonium carbamate believed to occur in the 
carbonate {see p. 96). 

NH.NH^CO, — H,0 = CO(NH2)2 

Tests for Urea. — 1. Crystals of urea, cautiously heated in a test- 
tube, give an odor of ammonia, and a substance called biuret is 
formed, which, when dissolved in water, gives a rose-red color on 
adding a trace of cupric sulphate and excess of potassium hydrox- 
ide. 

2. Concentrated solutions of urea, such as are obtained by evaju)- 
rat\ng normal urine to one-fourth of its bulk, give with an equal 
volume of concentrated nitric acid an abundant crop of crystals 



574 MORBID URINE. 

of urea nitrate, in octahedral and hexagonal prisms. Oxalic acid 
under similar conditions yields flat-rhombohedral prisms. 

3. Nitrous acid or hypobromites give a brisk effervescence of 
nitrogen. 

4. Caustic alkalies cause an evolution of ammonia. A similar 
production of ammonia is caused by several micro-organisms, not- 
ably micrococcus urece which is the cause of the decomposition of 
urea, with evolution of ammonia, observed in stale urine. An 
enzyme has been isolated from this organism which also decom- 
poses urea with evolution of ammonia. 

Physical Examination^ of Urine. 

Normal urine varies in color from a light straw yellow to dark 
brown, the average being a golden yellow. The pigment present 
in largest quantity and to which the normal color of urine is almost 
wholly due is urochrome. The other pigments present are, urobi- 
lin, uroerythrin, and hcematoporphyrin. The presence of blood 
causes a variation in color from a slight smoky brown to a deep 
red according to the amount of blood. Bile gives the urine a 
greenish-brown color. Both color and odor are much influenced 
by certain kinds of food and by some drugs. Thus santonin and 
chrysophanic acid color the urine orange. To distinguish these 
add sodium hydroxide, which gives a red color ; shake with amyl 
alcohol, when the color if due to santonin dissolves in the alcohol 
and then, in contact with air, changes to yellow ; the color due to 
chrysophanic acid does not dissolve in the amyl alcohol or only in 
traces (Hoppe-Seyler). The odor of diabetic urine not infrequently 
is that of acetone, from the presence of that substance. Many 
drugs, for example, cubebs, and some foods, as asparagus, give 
special odors to urine. 

Fresh urine is clear. Any turbidity may be due to urates, 
phosphates, fat-globules, or pus. Urates redissolve when the 
urine is warmed ; phosphates on addition of acetic acid ; pus and 
fat are detected by the microscope, vide infra. If the urine be 
turbid from the presence of phosphates when first voided, it may 
be due to conversion of urea into ammonium carbonate, which 
])recipitates the phosphates within the bladder, in which case the 
fresh and warm urine will effervesce slightly on the addition of 
acetic acid. This condition is abnormal. 

Oh standing, healthy urine commonly gives a slight cloud of 
mucus, and after severe exercise may give a sediment of urates. 

The specific gravity of urine should be taken on a specimen 
removed from the whole bulk excreted in twenty or twenty-four 
hours ; the normal specific gravity varies between 1.015 to 1.025. 
Many qualitative experiments and all quantitative operations 
should only be jDcrformed on the mixed urine of twenty-four 
hours. 



ALBUMIN. 



676 



Healthy urine when fresh is always slightly acid, the acidity 
being due to the presence of acid sodium phosphate. Alkalinity 
is probably due to that conversion of urea into ammonium car- 
bonate within the bladder already described. 



EXAMINATION OF MORBID URINE FOR ALBUMIN, SUGAR, 
BILE, BLOOD, EXCESS OF UREA, DEFICIENCY OF CHLO- 
RIDES, ETC. ; AND URINARY SEDIMENT FOR URATES (OR 
LITHATES), PHOSPHATES, CALCIUM OXALATE, AND URIC 
ACID. 

Albumin. — Faintly acidulate a portion of the clear urine 
in a test-tube with a few drops of dilute acetic acid (to keep 
phosphates in solution), and boil ; flocks or coagula will sepa- 
rate if albumin be present. To detect small quantities, nearly 
fill a long test-tube with clear urine filtered if necessary, and 
faintly acidulated with acetic acid ; then, holding the tube by 
its lower end, boil the upper portion of the urine. — A cloudi- 
ness in the boiled portion (as compared with the unboiled 
portion), which, on further addition of a few drops of acetic 
acid, does not disappear, indicates the presence of albumin. — 
Or, place a little nitric acid in a test-tube ; then carefully 
pour down the side of the tube a little of the urine, so that it 
may lie above the acid. If albumin be present, an amorphous 
whitish ring or coagulum will, sooner or later, be formed at 
the junction of the fluids (Heller's test). 

These experiments should first be made on normal urine con- 
taining a drop or two of solution of white of egg. The coagulum 
is white if it is only albumin, greenish if bile-pigment be present, 
and brownish-red if the urine contain blood. The influence of 
acids and alkalies on the precipitation of albumin is noticed on 
page 543. 

A saturated solution of picric acid at once precipitates any albu- 
min from urine. Should the urine be alkaline, it must be acidu- 
lated before applying this test. On warming the mixture, the 
precipitate will become more pronounced if due to the albumin or 
globulin of blood, or to any modifications of albumin catised by 
acidity or alkalinity of urine ; but will disappear if due to peptone 
or prepeptone. Potassium ferrocyanide, also, will precipitate the 
former varieties of albumin, but not the peptones. 

Other forms of Protcid. — Halliburton suggests the following 
sequence of operations for the detection of the various forms of 
proteid which may occasionally be present in abnormal urine. 1 . If 



I 




576 MOBBID URINE. 

the urine gives no precipitate on boiling after acidulation, albu- 
min and globulin are absent. If a precipitate occurs, albumin or 
globulin or both are present. 2. If the urine after neutralization 
gives no precipitate on saturation with magnesium sulphate, globu- 
lin and hetero-proteose are absent. " If such a precipitate occurs, 
one or other is present. 3. If the urine be saturated with ammo- 
nium sulphate, filtered, and the filtrate gives no xanthropoteic or 
biuret reaction — a rose-red color with cupric sulphate and a large 
excess of potassium hydroxide — peptone is absent. 4. If the urine 
gives no precipitation on boiling after acidulation, no precipitate 
with nitric acid, and no precipitate on adding ammonium sulphate 
to saturation, peptone can be the only proteid present. Confirm 
this by the biuret reaction. 

The occurrence of albumin in the urine may be temporary and 
of but little importance ; or it may indicate the existence of a 
serious affection, known as Bright' s disease. " Albuminaria is 
rarely a serious condition unless it is sufficiently pronounced to be 
made out by the cold nitric acid test." (Steward.) 

For quantitative purposes, Esbach employs the picric test, dis- 
solving 10 parts of picric acid and 20 of citric acid in 900 of water, 
by aid of heat, and when the solution is cold, diluting with water 
to 1000 parts. This solution is added to a given volume of urine 
in a graduated Cetti' s Esbach tube, and the height of the precipi- 
tate is noted after 24 hours. Johnson finds a simple solution of 
5 grains of picric acid in 1 fluid ounce of water better than Esbach' s 
solution, because the excess of acid in the latter tends to precipi- 
tate much uric acid which would be reckoned as albumin. If 
necessary, a standard value is given to the solution in the first 
instance by washing, drying and weighing the albumin. 

A peculiar form of albuminaria called " Bence Jones Albumo- 
suria" has now been described in a considerable number of cases. 
It is connected Avith a uniformly fatal multiple ulceration and 
softening of bone, and the proteid present is intermediate between 
albumin and the albumoses, being coagulable at a low temperature 
(60° C.) and redissolving to a great extent on boiling. It is also 
different from ordinary albumin in being readily soluble on boiling 
with hydrochloric acid. 

Sugar. — To a portion of the clear liquid in a test-tube add 
five to ten drops of solution of cupric sulphate ; pour in solu- 
tion of potassium hydroxide until the precipitate first formed 
is re-dissolved ; slowly heat the solution to near the boiling- 
point ; a yellow, yellowish-red, or red precipitate (cuprous 
oxide) is formed if sugar be present. (The production of 
rose-red or pink tint with the cold alkaline cupric solution 
indicates the presence of albumoses or peptones.) 



BILE. 517 

This experiment should first be made on urine containing a drop 

or two of grape-sugar (p. 482). The cupric hydroxide precipitated 
by the alkali is insoluble in excess of pure potassium hydroxide, 
but readily dissolves if organic matter, especially sugar, be present. 
The cupric salt should not contain iron. 

Other tests may be applied if necessary (see pp. 482 and 485). 
See also the Quantitative Determination of Sugar on p. 676. In 
any case in which, while the copper test points to sugar, medical 
diagnosis does not point to diabetes, the copper test should be 
checked by a fermentation test, for after the administration of 
chloral, camphor, morphine, phenol, and many other drugs, there 
may temporarily occur in the urine a compound termed glycuronic 
acid, which with the copper test affords a reaction identical with 
that of sugar. 

Sugar is present in minute traces only in normal urine. In 
searching for small quantities, uric acid and creatinine, which 
also reduce the copper-solution, should first be removed by precipi- 
tation with solution of mercuric chloride (in the presence of sodium 
acetate, which promotes the precipitation), and removal of excess 
of mercury from the clear liquid by addition of ammonia. Normal 
urine rotates the plane of polarization of light slightly to the left, 
but if even a small amount of sugar be present, dextro-rotation 
results. In larger quantities (often 5 percent.) sugar is a charac- 
teristic constituent of the urine of diabetic patients, greatly in- 
creasing the specific gravity of the secretion. Small hydrometers 
(termed urinometers) are commonly employed for ascertaining the 
specific gravity of urine. 

Bile. — This is detected by the dark greenish-brown color of the 
urine and by the general tests described on p. 550. In doubtful 
cases the urine should be thoroughly shaken up with a little chloro- 
form, which dissolves the bile-pigments, and Gmelin's test applied 
to the separated chloroform. Oliver recommends that the urine 
be diluted to a sp. gr. of 1.008 and then one volume be added to 
three volumes of the following reagent, when more or less opales- 
cence will be produced, according to the amount of bile acids 
present. For the reagent, dissolve 30 grains of flesh peptone, 4 
grains of salicylic acid, and 30 minims of official acetic acid, in 8 
ounces of water ; filter. 

Blood. — The presence of blood in the urine may be detected by 
the color if the amount be not too small, by the spectroscope, or 
by the guaiacum test, which consists in the production of a blue 
color when ozonic ether (made by adding hydrogen peroxide to 
ether) and tincture of guaiacum are added to the urine. This test 
is delicate, but is given by other substances, and ought to be con- 
firmed by other tests. 

Excess of Uris Acid. — A rough quantitative process con- 
sists in applying the qualitative method already described 
37 



578 MORBID URINE. 

(p. 345) to a known volume of urine, and collecting on a 
filter, washing and weighing the resulting uric acid. The 
result is always low. Hopkins saturates the urine with 
ammonium chloride, and, after a couple hours, decomposes 
the separated ammonium urate by means of hydrochloric acid, 
and collects, washes, dries, and weighs the resulting uric acid. 
The normal yield should be roughly 0.3 to 0.5 per 1000. See 
Proceedings of the Royal Society, vol. lii, p. 93. 

Excess of Urea. — About one-third of the solid matter in 
the urine is urea. Its proportion varies considerably ; but 2 
percent, may be regarded as an average quantity. With 
regard to the amount of urea in urine, it is impossible to 
sharply define excess or deficiency. If nitric acid, added in 
equal volume, gives crystals without concentration, excess is 
certainly present in the sample examined : though, if the 
amount of urine passed in the twenty-four hours is much 
below the average, the total quantity of urea excreted may 
not be abnormal. 

For quantitative determinations, the urine is treated in a 
suitable apparatus with an alkaline solution of recently prepared 
sodium hypobromite, and the nitrogen thus liberated is collected 
and measured. The reaction is of the following character: — 



COCNH,), + SNaBrO = 


SNaBr 


+ CO, + 


2H,0 + N, 


Urea Sodium 


Sodium 


Carbonic 


Water Nitrogen 


hypobromite 


bromide 


anhydride 





The carbonic anhydride represented in the equation is absorbed 
by the excess of alkali used in making up the hypobromite solu- 
tion, so that only the nitrogen is evolved in gaseous form. Only 
about 94 percent, of the nitrogen appears in gaseous form,^ and 
allowance must be made for this deficiency if an instrument grad- 
uated in Cc.'s is employed for the determination. Usually, the 
instruments used clinically are, however, graduated in percentages, 
and in that case allowance is made in the initial graduation of 
the instrument. 

Many forms of instrument have been devised for determining^ 
the urea from the evolved nitrogen in this reaction, but they all fall i 
into one of two classes: first, that in Avhich air is present over the' 
hypobromite, with which the evolved nitrogen mixes and in which | 
the amount of nitrogen is estimated from the increase inj 
volume of the gas which is driven into a graduated cylinder; and, 
secondly, those in which the nitrogen is evolved alone in a grad- 
uated tube filled with the hypobromite solution. The principle] 

• ^ In diabetic urine nearly the theoretical yield is obtained. 



UREA. 



579 



Fig. 49. 




of the first type of apparatus is shown in Fig. 49 which has been 
constructed from ordinary laboratory apparatus. The burette 
fixed in the stand has air-tight connec- 
tions above with the wide-mouthed bot- 
tle, and below with a funnel by means 
of rubber tubing. The burette is filled 
with water, which also fills the connect- 
ing tube and funnel to an equal level. 
The bottle contains 25 Cc. of the hypo- 
bromite solution, made by adding 2 Cc. 
of bromine to 23 Cc. of 40 percent, 
solution of sodium hydroxide, and 5 
Cc. of urine in a short wide test-tube 
are placed within the bottle, so that 
later, by tilting the bottle, the urine and 
hypobromite may be mixed. After 
placing the cork air-tight in the bottle, 
the level of the water in the burette is 
read, the water in the funnel being 
adjusted at an equal level, then the 
urine and hypobromite are mixed, and 
after an interval of ten minutes, the 

new level of the water is read. The difference in the readings gives 
the volume of nitrogen evolved; and 35.4 Cc. of nitrogen 
(measured at 18° C. and 760 mm. pressure) correspond to 0.1 
gramme of urea, from which the percentage of urea can easily be 
calculated. Care must be taken to keep the temperature constant 
throughout the experiment by immersing the bottle in a bath of 
water, otherwise a large error will result from the change in 
volume of the contained air. 

The other type of apparatus (Doremus Ureometer, Fig. 50) is 
simpler and sufficiently accurate for all clinical purposes. The 
hypobromite solution is made to completely fill a graduated tube 
closed at the upper end and bent in ' ' U " form at the bottom, 
beyond the bend a bulb is blown to contain the hypobromite 
displaced from the tube, and a short length of tubing reaches 
above the bulb. The tube is filled and also the bend and lower 
part of the bulb, by first filling the bulb with the solution and 
then slowly inverting so as to displace the air. On again turning 
up the tube the hypobromite completely fills the graduated tube, 
bend, and lower part of bulb. One Cc. of urine is now introduced 
by means of a bent pipette graduated to deliver 1 Cc. and filled 
and emptied by means of a rubber bulb at its end. Care must be 
taken to introduce all the urine and yet not to blow in bubbUs 
of air. In a recent modification the urine is added from a small 
graduated tube attached to the side of the hypobromite tube and 
separated from it by a stopcock. These instruments are usually 
graduated in percentages of urea to obviate calculations. 



580 



MORBID URINE. 



In these instruments no error is introduced from changes in 
volume of admixed air, and although the quantity of urine used 
is small, they are fairly accurate. 

A still more recent form of instrument for measuring small 
amounts of urea in blood or urine is that of Barcroft, in which 
the volume of gas and air is reduced to the same as that at the 
beginning, by applying pressure, and differences in pressure are 
measured instead of differences in volume. 

It may be said of all these instruments that they do not 
measure the amount of urea with scientific accuracy, because, in 
the first place, all the urea-nitrogen is not given off ; and, in the 
second, a small amount is set free from uric acid and other nitrog- 
enous substances present in the urine, but for clinical purposes they 
give a very close approximation to the amount of urea present. 
Chlorides. — Any ordinary sample of urine yields an abundant 
precipitate of silver chloride on the addition 
Fig. 50. of nitric acid and silver nitrate. The amount 

of chlorides present may be determined by any 
of the usual methods for the determination of 
chlorides. The normal quantity of chlorine 
present as chlorides is 0. 5 percent. ; but this 
may be reduced practically to nil in acute feb- 
rile conditions, such as pneumonia, partially 
from the stoppage of intake of chlorides in the 
food, and partially from increased metabolism 
of proteid binding the chlorides of the tissues, 
and blood, and lymph. 

Ckroriiogeiis. — Urine may contain chromo- 
gens. These are substances which do not at 
the time color the urine, but which, on the 
addition of oxidizing reagents, or after stand- 
Doremus ureometer. i^g some time, develop a color. A blue color 
may be seen in urine rich in indican on the ad- 
dition of much nitric acid. This is due to the formation of indigo 
from its chromogen. The darkening often noticed on the addi- 
tion of acid to urine is due to liberation of the urinary pigments 
from their chromogens. 

Acetone in urine occurs usually in the later stages of diabetes 
mellitus. Halliburton thus describes a delicate test by Le Nobel. 
On adding an alkaline solution of sodium nitroprusside, so dilute as 
to have only a slight red tint, to a fluid containing acetone, a ruby- 
red color is produced, Avhich in a few moments changes to yellow, 
and on boiling, after adding acid, to greenish-blue or violet. 

The iodoform test for acetone consists in adding a small crystal 
of iodine, or a few drops of iodine dissolved in solution of potassium 
iodide, then a solution of a caustic alkali, and Avarming, when the 
odor of iodoform is obtained. Alcohol nnist not be present, so 
that the iodine must on no account be added as Tinct, lodi. 




UREA. 



581 



Tlie Color of Urine. Caution. — Care must be taken not to con- 
found the color-changes in urine due to the action of drugs with 
the effects produced by the action of oxidizing agents on chromo- 
gens. Tlius rhubarb, saffron, and santonin darken the natural 
yellow of urine, the addition of an alkali causing a red colora- 
tion. Carbolic acid taken internally, or absorbed from exten- 
sive wounds after surgical operations, makes the urine greenish- 
black, resembling urine with much bile in it. If potassium 
iodide or bromide is being taken internally, the addition of a 
strong acid will often cause separation of iodine or bromine 
respectively in the urine. Medicinal astringents tend to reduce 
the normal color of urine. Many soluble inorganic and organic 
medicinal substances pass out of the system with the urine, some- 
times quite unchanged in character. Pepsin has been found in 
urine. ^ ' Small pieces of fibrin soaked in the urine absorb the 
pepsin therefrom; on removing them to 0.1 percent, hydrochloric 
acid they are rapidly digested" (Leo). 

Aceto-acetic acid is also found associated with acetone and /3-oxy- 
butyric acid in diabetic urine. It may be detected by adding very 
dilute solution of ferric chloride cautiously drop by drop to the 
suspected urine. The first portion added precipitates the phos- 
phates, which if present in excess may be filtered off. The first 
trace of ferric chloride after the phosphates have been precipi- 
tated gives a burgundy red color, which disappears on heating 
the solution, and does not re-appear on cooling. This final stage 
of the test ought always to be performed, since it serves to dis- 
tinguish the aceto-acetic acid from other substances which may be 
present, and give a similar result in the first part of the test, i. e., 
the color reaction with ferric chloride in the cold. 

Urinaiiy Sediments. 
Warm the sediment with the supernatant urine, and filter. 



Insoluble. 

Phosphates, calcium oxalate, and uric acid. 
Warm with acetic acid, and filter. 



Insoluble. 

Calcium oxalate and uric acid. 

Warm with hydrochloric 

acid, filter. 



Insoluble. 

Uric acid. 

Apply tlie 

murexid test 

(p. 346). 



'Soluble. 

Calcium 

Oxalate. 

May be repre- 

c'ipitated by 

ammonia. 



Soluble. 

Phospliates. 

Add ammonia ; 
white ppt.=:cal- 
cium phosphate 
or a m m o n i u m 
ni a g n e s i u m 
ph o s pli a t e, or 
both. 



Soluble. 

Ammonium, cal- 
cium, or sodium 
urates; chiefly 
the latter. 

They are re- 
deposited as the 
liquid cools, and 
if sufficient in 
quantity may 
be further ex- 
a m i n e d for 
ammonium, cal- 
cium, s o d i u ni, 
and the nric acid 
radical by theajv 
pi-opriate tests. 



582 MORBID URIXE, 

Xotes. — Urinary deposits are seldom of a complex character: 
the action of lieat and acetic and hydrochloric acids generally at 
once indicates the character of the deposit, rendering filtration 
and precipitation unnecessary. 

The Urates are often of a pink or red color, owing to the pres- 
ence of a pigment termed uroerythrin or purpurin ; hence the 
common name of red gravel for such deposits. Purpurin is solu- 
ble in alcohol, and may be removed by dissolving the deposit by 
heating, and extracting with amyl alcohol. It is seldom neces- 
sary to determine whether the urate be that of ammonium, cal- 
cium, or sodium [see also Uric acid, p. 345). The deposited urate 
is a very acid urate (quadriurate) which slowly (more rapidly in 
urine diluted with water) breaks up into a less acid urate (biurate) 
and uric acid (Bence Jones), the supernatant urine becoming at 
the same time less acid owing to the formation of mono- from di- 
hydrogen phosphates. The presence in the urine of mono-hydro- 
gen phosphates, is apparently (Roberts) what prevents this decom- 
position before the urine is exposed to the air. 

Calcium j^f^osphate and arnriioniurn magnesium phosphate 
(XHpigPO^), are usually both j^resent in a phosphatic deposit, 
the magnesium salt forming the larger proportion. They may, if 
necessary, and if sufficient in quantity, be separated by collecting 
on a filter, washing, and boiling with solution of sodium carbon- 
ate. The calcium and magnesium carbonates thus formed are col- 
lected on a filter, washed, and dissolved in a drop or two of hydro- 
chloric acid; ammonium chloride, ammonia, and ammonium car- 
bonate are added, and the mixture boiled and filtered; any calcium 
originally present will then remain insoluble, as calcium carbonate; 
while any magnesium will be precipitated from the filtrate as 
ammonium magnesium phosphate on the addition of sodium phos- 
phate, the mixture being also well stirred. — The chief portion 
of excreted earthy phosphates is carried off* by the faeces,, that 
remaining in the urine being kept in solution by the influence of 
acid sodium phosphate and, frequently, lactic acid. — Occasionally, 
an hour or two after a hearty meal, the urine becomes suffi- 
ciently alkaline for the phosphates to be deposited, and the urine 
when passed is turbid from their presence. — The ammoniacal con- 
stituent of the ammonium magnesium salt does not occur normally, 
but is produced from urea as soon as urine becomes alkaline. 

Calcium oxalate is seldom met Avith in excessive amounts, but 
very often in small quantities mixed with phosphates. In the 
urine it is probably kept in solution by the influence of the acid 
sodium phosphate. In one case of oxaluria the whole urine 
excreted by the patient in twenty-four hours furnished to the 
author only two-thirds of a grain of calcium oxalate. 

Free uric acid is in most cases distinctly crystalline, and nearly 
always of a yellow, red, or brown color owing to the presence of 
impurities. 



URINARY SEDIMENTS. 583 

Artifirial Sediments. — For educational practice, these may be 
obtained as follows: — 1. Triturate in a mortar a few grains of ser- 
pent's excrement (chiefly ammonium urate) with an ounce or two 
of urine ; this represents a sediment of urates. 2. Add a few 
drops of ammonia water or solution of ammonium carbonate to 
urine; the deposit may be regarded as one of phosphates. 3. 
To an ounce or two of urine add very small quantities of cal- 
cium chloride and ammonium oxalate ; the precipitate is calcium 
oxalate. 4. To urine acidulated with hydrochloric acid add a 
little serpent's excrement; the sediment is uric acid. 

Other deposits than the foregoing are occasionally observed. Thus 
hippiiric acid, HCgHgNOg, a normal constituent of human urine 
and largely contained in the urine of herbivorous animals, is 
sometimes found associated with uric acid in urinary sediments, 
especially in those from patients whose medicine contains benzoic 
acid (p. 325). Its appearance, as observed by aid of the micro- 
scope, is characteristic — namely, slender, four-sided prisms, hav- 
ing pointed ends. Ct/stin, CgH^NSOg (from k,vgtl(;, kustis, a blad- 
der, in allusion to its origin) rarely occurs as a deposit in urine. 
It is not soluble in warm urine or dilute acetic acid, and scarcely 
in dilute hydrochloric acid — hence would be met with in testing 
for free uric acid. It is very soluble in ammonia, recrystallizing 
from a drop of the solution placed on a piece of glass in charac- 
teristic microscopic six-sided plates. It communicates an odor, as 
of sweet briar, to fresh urine, soon changing to a most unpleasant 
smell. Leucine and tyrosine {see p. 510) are occasionally met with 
in cases of phosphorus poisoning and of acute yellow atrophy of 
the liver. As a rule they occur together in the form of small 
round yellowish masses of radiating crystals. Organized sedi- 
ments may be due to the corpuscles of pus, mucus, or blood, fat- 
globules, spermatozoa, cylindrical casts of the tubes of the kid- 
neys, epithelial cells from the walls of the bladder, or foreign 
matters, such as fibres of wool, or of cotton or wood, small feath- 
ers, dust, starch, etc. ; these are best recognized by the microscope. 
(See the accompanying illustrations, and the following paragraphs 
on the microscopic appearances of both crystalline and organized 
urinary sediments. ) 

Microscopic Examination of Urinary Sediments. 

Urine containing insoluble matter is usually more or less opaque. 
For microscopical examination a few ounces should be set aside 
in a conical test-glass for an hour or two, the clear supernatant 
urine poured off" from the sediment as far as possible, a small 
drop of the residue placed on a slip of glass, covered with a 
cover-slip, and examined under the microscope with ditleront 
magnifying powers. 



584 



MORBID URINE. 



The respective appearances of the various crystalline and or- 
ganized matters are given in Figs. 51 to 62 which Avere kindly 
drawn by the late H. B. Brady, F. R. S., from natural specimens 
in the collections of 8t. Bartholomew's Hospital, Dr. Sedgwick, 
the late Mr. W. W. Stoddart, Mr. Waddington, and the Author. 

Uric acid occurs in many lorms, most of which are given in 
Figs. 51 and 52. Flat more or less oval crystals, sometimes 
attached to each other, their outline then resembling an 8, a 
cross, or a star, are common. Single and grouped quadratic 
prisms, aigrettes, spicula, and crystals recalling dumb-bells are 



Fig. 51. 



Fig. 52. 




Uric acid. 



Uric acid. 



met with. From urine acidulated with hydrochloric acid, bun- 
dles or sheaves of square crystals, two opposite sides smooth and 
two jagged, are generally deposited : acidulated with acetic acid, 
more typical forms are obtained. A drop of solution of potas- 
sium hydroxide placed on the glass slip will dissolve a deposit 
of uric acid, a drop of any acid reprecipitating it in minute but 
characteristic crystals. 

Cystin is very rarely met with as an urinary deposit ; that from 
which Fig.^ 53 was taken was found in the urine of a patient 
in St. Bartholomew's Hospital. Lamellae of cystin always 
assume the hexagonal character ; but the angles are some- 
times ill-defined and the plates superposed : in the latter case, 
a drop of ammonia water placed on the glass at once dissolves 
the deposit, well-marked six-sided crystals appearing as the drop 
dries up. 

Triple phosphate (ammonium magnesium phosphate) is deposited 
as soon as urine becomes alkaline, the ammoniacal constituent 
being furnished by the decomposition of urea. It occurs in large 
prismatic crystals, forming a beautiful object when viewed by ,| 
polarized light, — sometimes also in ragged stellate or arborescent 



URINARY SEDIMENTS. 



585 



crystals, resembling those of snow. Both forms may be artificially 
prepared by adding a small lump of ammonium carbonate to a 
few ounces of urine and setting aside in a test-glass. (Fig. 54.) 

Amorphous deposits are either earthy phosphates (a mixture of 
magnesium and calcium phosphates) or urates of calcium, mag- 
nesium, ammonium, potassium, or sodium — chiefly the latter. 
They may be distinguished by the action of a drop of acetic acid 
placed near the sediment on the glass slip, the effect on mixing 
being watched under the microscope ; phosphates dissolve, while 



Fig. 53. 



Fig. 54. 




Cystin. 



Triple phosphate. 



urates give rise to characteristic forms of uric acid. Urates redis- 
solve when warmed with the supernatant urine. 

Sodium and magnesium urates, though generally amorphous, 
occasionally take a crystalline form — bundles or tufts of small 
needles — as shown in Figs. 55 and 56. When pink or brick-red, 
the color is due to uroerythrin. 

Calcium oxalate commonly occurs in octahedra requiring highly 
magnifying-power for their detection. The crystals are easily over- 
looked if other matters are present, but are more distinctly seen 
after phosphates have been removed by acetic acid. In certain 
aspects the smaller crystals look like square plates traversed by a 
cross. A dumb-bell form of this deposit is also sometimes seen, 
resembling certain forms of uric acid and the coalescing spherules 
of a much rarer sediment — calcium carbonate. Calcium oxalate 
is insoluble in acetic but soluble in hydrochloric acid. The octa- 
hedra are frequently met with in the urine of persons who have 
partaken of garden rhubarb and certain other vegetables. The 
crystals may often be deposited artificially (according to Wadding- 
ton) by dropping a fragment of oxalic acid into several ounces of 
urine and setting aside for a few hours. 



586 



MORBID URINE. 



Calcium carbonate is rarely found in the urine of man, but 
frequently in that of the horse and other herbivorous animals. 
Human urine containing calcium carbonate often reddens litmus- 
paper ; and it is only after the removal, on standing, of the excess 
of carbonic acid, that the salt is deposited. It consists of minute 
spherules, varying in size, the smaller ones often in process of 
coalescence. The dumb-bell form thus produced is easily dis- 
tinguished from similar groups of uric acid or calcium oxalate by 
sho'rting a black cross in each spherule when viewed by polarized 
light. Acetic acid dissolves calcium carbonate, liberating car- 
bonic anhydride with visible effervescence (under the microscope) 
if the slide has been previously warmed and a group of crystals be 
attacked. 

Fig. 55. Fig. 56. 




Urates 

a, of Sodium; 

b, of Magnesium. 



-Calcium oxalate. 



Calcium carbonate. Hippuric acid. 



Hippuric acid.— The pointed rhombic prisms and acicular crys- 
tals are characteristic and easily recognized. The broader crvstals 
may possibly be mistaken for triple phosphate, and the narrower 
for certain forms of uric acid ; but insolubilitv in acetic acid dis- 
tinguishes them from the former, and solubility in alcohol from 
the latter. These tests may be applied while the deposit is under 
microscopic observation. An alcoholic solution of hippuric acid 
evaporated to dryness, and the residue treated with water, gives 
a solution from which characteristic crystalline forms of hippuric 
acid may be obtained on allowing a drop to dry on a slip of glass. 

The organized deposits in urine entail greater care in their deter- 
mination, and usually require a higher magnifving power for their 
proper examination than those of cr^'stalline form. The figures 
are drawn to 230 diameters. The following notes will assist the 
observer: 

Co.sfs of uriniferouf^ fxbun are of various forms, and often of con- 
siderable length— sometimes delicate and transparent, occasionally 



URINARY SEDIMENTS. 



587 



granular, and often beset with fat-globules. Epithelial debris are 
frequently present in urine in the form of nucleated cells, regular 
and oval when full, but angular and unsymmetrical when parti- 
ally emptied of their contents — sometimes perfect, but more 
frequently broken up. Casts are very readily discovered by the 
use of the microscope, if, to a sample of the urine supposed to con- 
tain them, best in a conical glass, a few drops of an aniline dye be 
added. ' ' Carbofuchsine ' ' answers well. The casts rapidly stain, 
and are then quite easily seen in the field. (Fig. 57). 

Blood corpuscles are readily identified under the microscope by 
their characteristic appearance ; they are usually crenated when 
present ; if the haemoglobin has escaped, the stroma is often 



Fig. 5' 



Fig. 58. 




Epithelial cells and tubuli 



Blood-corpuscles. 



visible for some time, forming what is termed a shadow. The tests 
for blood, or rather haemoglobin in solution, have already been 
described {see p. 577). It is noteworthy that when the blood is 
present in small quantities the spectrum obtained is that of 
methsemoglobin and not that of oxyhsemoglobin. When corpus- 
cles are present, the condition is known as hsematuria ; when the 
blood coloring-matter is in solution, as haemoglobinuria. 

It is not possible to state with certainty whether the blood cor- 
puscles found in urine are those of man, or of the domestic mam- 
malia, for the slight differences in size are not sufficiently charac- 
teristic or fixed. 

Pus and mucus. — Purulent urine deposits, on standing, a light- 
yellow layer, easily diffused through the liquid by shaking. Acetic 
acid does not dissolve the sediment ; and soluf'wn of potassium 
hydroxide of official sfrenyfh con verts it info a gelatinous mass. ITnder 
the microscope, pus-corpuscles appear rounded and colorless, 
rather larger than blood-disks, and somewhat granular on the sur- 



588 



MORBID URINE. 



face. The corpuscles may be made more distinct by staining 
with a dilute solution of methylene blue. They generally show 
minute nuclei, which are more distinctly seen after treatment with 
acetic acid. {See the portion of Fig. 59 marked a.). Mucus pos- 



FiG. 59. 



Fig. 60. 




Pus-corpuscles. 



Fat-globules. 



/7) sesses no definite microscopic characters, but commonly has im- 

bedded in it pus, epithelium, and air-bubbles. Mucus is coagu- 
lated in a characteristic manner by acetic acid ; anxl this reaction, 
together with the ropy appearance it imparts to urine, prevents it 
being confounded with pus. 



Fig. 62. 




SpernAt 



Sarcina ventriculi. 



Fatty matter (lipuiria) occurs either as minute, highly refractile, 
glittering globules partially diffused through the urine (as shown 



URINARY CALCULI. 589 

at a) or in more intimate emulsion (as at b in Fig. 60). When 
present in larger quantity, it collects as a sort of skim on the sur- 
face after standing. 

Spermatozoa are liable to escape notice, on account of their small 
size and extreme transparency. Suspected urine should be allowed 
to settle some hours in a conical test-glass, and the drop at the 
bottom examined under a high power. Fig. 61 shows their 
appearance. They become more apparent after staining by an ani- 
lin dye such as methylene blue. 

Sarcince rarely occur in urine, but are not infrequent in vomited 
matters. The upper figures (Fig. lo'l, a) are copied from Dr. 
Thudichum's drawing (from urine); the larger groupings (6) are 
from vomited matter. 

Extraneous bodies, such as starch, hair, wool, fibres of cotton or 
of deal, or fragments of feathers, are often found in urinary 
deposits ; and ludicrous mistakes have been made by observers not 
on their guard in respect to such casual admixtures. 

Examination of Urinary Calculi. 

The term calculus is the diminutive of calx, a lime- or chalk-stone. 

The following calculi have been met with : — (1) Uric acid, (2) 
Sodium urate, (3) Calcium oxalate (mulberry), (4) Fusible or 
mixed calcium and triple phosphates, (5) Calcium phosphate, (6) 
Calcium carbonate, (7) Xanthine, (8) Cystin, (9) Urostealith (fatty 
matter), (10) Indigo (one case), l--' 

Knowledge of the composition of a calculus or urinary deposit 
affords valuable diagnostic aid to the physician ; hence the import- 
ance of a trustworthy analysis of these substances. 

Nature of Oalculi. — Urinary calculi have the same composition 
as unorganized urinary sediments. They consist, in short, of sedi- 
ments that have been deposited slowly within the bladder, particle 
on particle, layer on layer, the several substances becoming so com- 
pact as to be less easily acted on by reagents than when deposited 
after the urine has been passed — the urates less readily soluble in 
warm water, the calcium phosphate insoluble in acetic acid until 
it has been dissolved in hydrochloric acid and reprecipitated by an 
alkali. 

Preliminary Treatment. — If the calculus is whole, saw it in two 
through the centre, and notice whether it is built up of distinct 
layers or apparently consists of one substance. If the latter, use 
about a grain of the sawdust for analysis ; if the former, carefully 
scrape off portions of each layer, and examine them separately. If 
the calculus is in fragments, select fiiir specimens of about half a 
grain or a grain each, and reduce to a fine powder by placing on 
a hard surface and crushing under the blade of a knife. 

Analysis. — Commence the analysis by heatino- a portion, 
about the size of a pin's head, on platinum foil, in order to 



590 



MORBID URINE. 



ascertain whether organic matter, inorganic matter, or both 
are present. If both, the ash is examined for inorganic 
substances, and a fresh portion of the calculus for uric acid 
by the murexid test. (In the absence of uric acid any slight 
charring may be considered to be due to indefinite organic 
matter.) If composed of organic matter only, the calculus 
will in nearly all cases be uric acid, the indication being con- 
firmed by applying the murexid test in a watch-glass to an- 
other fragment, half the size of a small pin's head. If in- 
organic only, the ash on the platinum foil may be examined 
for phosphates, and a separate portion of the calculus for 
oxalates. Even a single drop of liquid obtained in any of 
these experiments may be filtered by placing it on a filter not 
exceeding 20 mm. in diameter and previously moistened with 
water, and adding three or four drops of water, one after the 
other as each passes through the paper ; or a drop of the mix- 
ture may be placed on a fragment of damped filter-paper 
on a glass slide, the latter then tilted, and a clear drop be 
drained off" from the paper on to the slide ready for the addi- 
tion of a reagent. If the calculus is suspected to contain 
more than one substance, boil about a grain of the powder in 
half a test-tubeful of distilled water for a few minutes and 
pour it on a small filter ; then proceed according to the follow- 
ing Table : — 





Insoluble. 


Soluble. 


Phosphates, 


calcium oxalate, and free uric acid. 


Urates. 


Boil with two or three drops of h3'drochloric 


These will prob- 




acid, and filter. 


ably be redepos- 
ited as the solution 






cools. Small quanti- 


Insoluble. 


Soluble. 


ties may be detected 
by evaporating the 


Uric acid. 


Phosphates and calcium oxalate. 


solution to dryness. 


Apply the 


Add excess of ammonia, and then 


They are tested for 


murexid 


excess of acetic acid ; filter. 


a m m n i u m, so- 


test 
(p. 346). 




dium, calcium, and 






the uric acid radi- 




Insoluble. 


Sohikle. 


cal by the appropri- 
ate reagents. 




Calcium 


Phosphates. 


. 




oxalate. 


They may be 
re-pptd. by annnonia. 


J 



UEII^ABY CALCULI. 



591 



Varieties of Calculi. — Calculi composed entirely of uric acid are 
common; a minute portion heated on platinum foil chars, burns, 
and leaves scarcely a trace of ash. The phosphates frequently 
occur together, forming what is known as the fusible calculus, from 
the readiness with which a fragment aggregates, and even fuses to 
a bead, when heated on a loop of platinum wire in the blow] ipe- 
flame. The phosphates may, if necessary, be examined further 
by the method described in connection with urinary deposits. 
Calcium oxalate often occurs alone, forming a dark-colored calculus 
having a very rough surface, hence termed the mulberry calculus. 
Smaller calculi of the same substance are called, from their appear- 
ance, hempseed calculi. Calculi of cystin are rarely met with. 
Xanthine (from ^avdog xanthos, yellow, in allusion to the color it 
yields with nitric acid) still less often occurs as a calculus. The 
earthy concretions or ^^ chalk-stones,^' which frequently form in 
the joints of gouty persons, are composed chiefly of biurates, the 
sodium salt being that most commonly met with. Gall-stones or 
biliary calculi, occasionally form in the gall-bladder ; they consist 
chiefly of cholesterin (from x^^'^V^ chole, biles, and ortpeo^, stereos, 
solid), C2-H^.0H, which is chemically an alcohol, but in its solu- 
bilities resembles the fats; it is soluble in alcohol or ether, 
and crystallizes from such solutions in well-defined, square, scaly 
crystals which are characterized by possessing a notch at one 
corner. Phosphatic and other calculi of many pounds weight 
are occasionally found in the stomach and larger intestines of 
animals. 



QUESTIONS AND EXERCISES. 

In breathing, how much carbon (in the form of carbonic anhydride) is 
exhaled from the lungs every twenty -four hours ? — How may the presence 
of carbonic anhydride in expired air be demonstrated ? — Mention an exper- 
iment showing the escape of moisture from the lungs during breathing. — 
State the method of testing for albumin in urine. — Give the tests for sugar 
in urine. — What is the average composition of healthy urine? — Give the 
tests for urea.— Write the rational formulae of some compound ureas in 
which methyl or ethyl displaces hydrogen.— Describe an artificial process 
for the production of urea, giving equations. — Sketch out a plan for the 
chemical examination of urinary sediments. — A deposit is insoluble in the 
supernatant urine or in acetic acid ; of wliat substance may it consist? — 
Which compounds are indicated when a deposit redissolves on warming it 
with the supernatant urine? — Name the salts insoluble in warmed urine, 
but dissolved on the addition of acetic acid. — Mention the chemical char- 
acters of cystin.— At what stage of analysis would it be I'ecognizod? — 
Describe the microscopical appearances of the following urinary dei>osits : 
uric acid, cystin, triple phosphate, calcium iiliosphate, urates, calcium 
oxalate, calcium carbonate, hippuric acid, tube-casts, epithelial debris, 
blood, pus, mucus, fat, spermatozoa. sarcina>, extraneous bodies. — State 
the physical and chemical characters of urinary calculi.— How are 



592 OFFICIAL GALENICAL PEEPA RATIONS. 

urinary calculi prepared for chemical examination '?— Construct a scheme 
for the chemical examination of urinary calculi. — What is the composi- 
tion of '•fusible calculus,' and why is this calculus so-called?— State the 
characters of ".mulberry ' and " hempseed " calculi.— What are " chalk- 
stones " of gout, and "gall-stones" or "biliary calculi?" 



THE GALENICAL PREPARATIOXS OF THE 
UNITED STATES PHARMACOPOEIA 

The preparation of Cerates, Confections, Decoctions, 
Extracts, Glycerites, Infusions, Juices, Liniments, Lozenges, 
Mixtures, Ointments, Pills, Plasters, Powders, Spirits, Sup- 
positories, Syrups, Tinctures, and Wines, includes a number 
of mechanical rather than chemical operations, and belongs to 
the domain of pure Pharmacy. The medical or pharmaceu- 
tical student will probably have had some opportunity of 
practically studying these compounds before working at exper- 
imental chemistry, and may have prepared many of them 
according to the directions of the Pharmacopoeia ; if not, he is 
referred to the pages of the last edition of that work for 
details. 



THE CHEMICAL PREPARATIONS OF THE 
UNITED STATES PHARMACOPOEIA 

Processes by which many official chemical substances may 
be prepared have now been described, and the strictly chem- 
ical character of the processes has been illustrated by experi- 
ments and explained by aid of equations. Should the reader, 
in addition, desire an intimate acquaintance with those details 
of manipulation on which the successful and economic manu- 
facture of chemical substances depends, he is advised to pre- 
pare, if he has not done so already, a few ounces of each of 
the salts mentioned in the Pharmacopoeia or commonly used 
in Pharmacy. A Dictionary or some of the larger text-books 
of Chemistry may also be consulted. 

The production of many chemical and galenical substances 
on a commercial scale can only be successfully carried on in 
manufacturing laboratories, and with some knowledge of the 
circumstances of supply and demand, and of the value of raw 



QUANTITATIVE MEASUREMENTS. 



593 



material, by products, etc.; for the technical preparation of 
such substances requires much knowledge beyond even a 
thorough acquaintance with chemistry. Still, in the present 
day, commercial Chemistry and Pharmacy can best hope for 
success when founded on the working out of abstract scientific 
principles. The problem of manufacturing success is now only 
solved with certainty by sound and wisely-applied science. 



QUANTITATIVE MEASUREMENTS 

Temperature 

General Principles. — As a general rule, to which, however, 
there are some exceptions, substances expand when heated and 
contract when cooled, the alteration in volume being approxi- 
mately constant and regular for equal increments or decrements of 
temperature. The extent of this alteration in a given substance, 
expressed in parts or degrees, constitutes the usual method of 
intelligibly stating with accuracy, precision, and minuteness a 
particular condition of warmth or temperature — that is, of sensible 
heat. The substance commonly employed for this purpose is 
mercury, the chief advantages of which are, that it will bear a 
moderately high temperature without boiling, a low temperature 
without freezing, does not adhere to glass to a sufficient extent to 
' ' wet ' ' the sides of any tube in which it may be enclosed, and, 
from its good conducting-power for heat, responds rapidly to 
changes of temperature. Platinum earthenware, alcohol, and 
air are also occasionally used for thermometric purposes. 



The Thermometer. — The construction of an accurate ther- 
mometer is a matter of considerable difficulty ; but the follow- 
ing are the leading steps in the operation. Select a piece of 
glass tubing having a fine capillary (eapillus, a hair) bore, 
and about a foot long ; heat one extremity in a blowpipe- 
flame until the orifice closes, and the glass is sufficiently soft 
to admit of a bulb being blown ; heat the bulb to expel air, 
immediately plunging the open extremity of the tube into 
mercury ; the bulb having cooled, and some mercury having 
entered and taken the place of expelled air, again heat the bulb 
and the tube until the mercury boils and its vapor escapes 
through the bore of the tube ; again plunge the extremity under 
mercury, which will probably now completely fill the bulb 
and tube. When cold, the bulb is placed in melting ice. 
38 



594 QUANTITATIVE MEASUREMENTS. 

The top of the column of mercury in the capillary tube 
should then be within an inch or two of the bulb ; if higher, 
some of the mercury must be expelled by heat ; if lower, more 
metal must be introduced as before. The tube is now heated 
near the open end and a portion drawn out, until the diameter 
is reduced to about one-tenth. The bulb is next warmed 
until the mercurial column rises above the constricted part of 
the tube, which is then rapidly fused in the blowpipe-flame, 
and the extremity of the tube removed. 

The instrument is now ready for graduation. The bulb is 
placed in the steam just above some rapidly boiling water 
(a medium having, cceteris parihus, an invariable tempera- 
ture), and when the position of the top of the mercurial 
column is constant (the flask containing the water and steam 
being jacketed to prevent loss of heat by radiation), a tem- 
porary mark is made on the stem to indicate this position. 
This operation is repeated with melting ice (also a medium 
having an invariable temperature). The space between these 
two marks is divided into a certain number of intervals 
termed degrees. Unfortunately, this number is not uniform 
in all countries : in Britain it is 180, as proposed by Fahren- 
heit ; in France 100 (the Centigrade scale) as proposed by 
Celsius, a number generally adopted by scientific men ; in 
some parts of Europe the divisions are 80 for the same 
interval, as suggested by Reaumer. Whichever be the 
number selected, similar markings should be continued beyond 
the boiling and freezing points as far as the length of the stem 
admits. They may be etched permanently on the stem itself, 
or on any wood, metal, or earthenware frame on which the 
stem is mounted. 

In ascertaining the temperatnre of a liquid, the bulb of a 
thermometer is simply inserted and the degree noted. In 
determining the boiling-point, also, the bulb may be inserted 
in the liquid, if a pure substance. In taking the boiling-point 
of a substance which is being distilled from a mixture, the 
bulb of the thermometer should be in the vapor but not 
beneath nor very near to the surface of the boiling liquid. 

The *' boiling-point " of a liquid is the temperature at which 
the pressure of the vapor of the substance overcomes the 
atmospheric or other pressure to which the liquid is exposed. 
When the pressure is equal to 760 mm. (29.92 inches) of 
mercury, water boils at 100° C. (212° F.). The boiling- 
point of a drop of a fluid is taken by introducing it into the 



TEMPERATURE. 



595 



closed extremity of a small U tube, the remaining portion of 
the closed limb being filled with mercury. The tube is low- 
ered into a bath, the open limb being above the surface of 
the fluid of the bath. The bath is slowly and equally heated, 
and the boiling-point of the liquid, indicated by the mercury 
falling until it is level in the two limbs, taken by a thermom- 
eter whose bulb is close to the U tube. 

Determination of Boiling-Point. — " To determine the boil- 
ing-point of a substance, the liquid under examination should 
be placed in a distilling flask having a side tube for convey- 
ing the vapor to a condenser, while the thermometer passes 
through a cork inserted in the neck. The bulb of the ther- 
mometer should be near to, but not immersed in, the liquid, 
and the whole of the thread of mercury should, if possible, be 
surrounded by the vapor ; the temperature is read ofi" as soon 
as the liquid is distilling freely. If any considerable length of 
the mercurial column be not surrounded by the vapor, the 
temperature of the emergent column should be ascertained as 
directed under melting-points [see next page], and the neces- 
sary correction applied." — B. P., 1898. 

The following are the boiling-poijits of a few substances met 
with in pharmacy : — 





Centigrade. 


Fahrenheit. 


Alcohol, absolute 


78.3 
132.2 

80.4 

63 
60 to 61 

35.5 
304 
357.25 
188 
100 

99.5 

99 
101 
106.6 
113.3 
119 
124.4 
179.4 


173 


amyl 


270 
176 7 


Benzol 


Bromine 


145 4 


Chloroform 


1 40 to 1 41 8 


Ether (Cabout) 


96 


Mercury in vcwuo (as in a thermometer) . 
" in air (barom. at 30 inches) . . 

Phenol (not higher than) 

Water (barom. at 29.92 inches) 

" ( " 29.33 " ) 

" ( '' 28.74 " ) 

Saturated solutions of :— 

Cream of tartar 

Common salt 

Sal-ammoniac 

Sodium nitrate 


580 

675.05 

370.4 

212 

211 

210 

214 
224 
236 
246 


" acetate 


256 


Calcium chloride 


355 



596 QUANTITATIVE MEASUREMENTS. 

Determinatioii of Melting-Point. — To melt at a given tem- 
perature is a constant property of a substance ; therefore a 
melting-point, once it is accurately determined, becomes a valu- 
able indicator of purity in a substance. The description given 
in the British Pharmacopoeia of 1898 of the mode of making a 
melting-point determination is as follo^ys : — "To determine the 
melting-point of a substance a minute fragment of it should 
be placed in a thin-walled glass tube having an internal diam- 
eter of about 1 millimetre (^V iiich), and sealed at the lower 
end. This tube should be attached to the thermometer so 
that the substance is near the middle of the bulb, and the 
thermometer with the attached tube should be immersed in a 
suitable liquid, contained in a beaker placed over a small lamp 
flame. Water is suitable for substances melting below 212° 
F. (100° C), sulphuric acid, hard paraffin, or glycerin for 
substances melting at higher temperatures. The liquid should 
be continually stirred by means of a glass ring moved up and 
down until the substance is seen to melt. The temperature is 
noted, the tube cooled until the substance solidifies, and the 
operation then repeated. The latter reading of the thermom- 
eter should be taken as the melting-point. To obtain accu- 
rate results, the whole of the mercury column of the thermom- 
eter should be immersed in the heated liquid, but as this is 
seldom practicable, the mean temperature of the emergent 
column — that is, of that portion above the surface of the 
heated liquid — should be ascertained and the necessary correc- 
tion applied. To obtain the mean temperature of the emer- 
gent column, a small thermometer is fixed by India-rubber 
bands in such a position that its bulb is about the middle of 
the emergent column. The corrected temperature may be 
calculated with approximate accuracy from the formula : — 



Corrected Temperature=T+. 000143 (T - t)N, 

in which 

T:=observed, i.e., uncorrected, temperature ; 
t=mean temperature of the emergent column ; 
K=the length of the emergent column in scale degrees." 



! 



TEMPERATURE. 



597 



The following are melting-points of substances official in the 
Pharmacopoeia : — 



Acetic acid, glacial 

" " congeals at 

Benzoic acid 

Oil of theobroma 

Phosphorus 

Prepared lard ....... 

" suet . . • 

Spermaceti 

White wax 

Yellow wax 



In degrees 


In degrees 


Centigrade. 


Fahrenheit. 


15.5 


60 


1.1 


34 


121.4 


250.5 


30 to 35 


86 to 95 


44 


111.2 


38 to 40 


100.4 to 104 


45 to 50 


113 to 122 


45 to 50 


113 to 122 


64 to 65 


147.2 to 149 


62 to 64 


143.6 to 147.^ 



Pyrometers. — Temperatures above the boiling-point of mer- 
cury are determined by ascertaining to what extent a bar of 
platinum or porcelain has elongated. The bar is enclosed in 
a cavity of a suitable case, a plug of platinum or porcelain 
placed at one end of the bar, and the whole exposed in the 
region the temperature of which is to be found. After cool- 
ing, the distance to which the bar has forced the plug along 
the cavity is accurately measured and the corresponding 
degree of temperature noted. The value of the distance is 
fixed for low temperatures by comparison with a mercurial 
thermometer, and the scale carried upward through intervals 
of equivalent length. Such thermometers are conventionally 
distinguished from ordinary instruments by the name pyrom- 
eter (from TTop, pur, fire and ij.irpov, metron, measure). 

The order of fusibility of a few of the metals is as follows : — 



Mercury 
Potassium 
Sodium 
Tii^i 1 . 
Bigmuth 
Leid . . 
Zinc . . 
Antimony 
Silver 
Cop^aer . 
Gold^ .'. 
Cast liron 



In degrees 
Centigrade. 



-39.4 

f 62.5 

97.6 

227.8 

264 

325 

411.6 

621 
1023 
1091 
1102 
1530 



In degrees 
Fahrenheit. 



— 39 

- 144.5 
207.7 
442 
507 
617 
773 

1150 
1873 
1996 
2016 
2786 



598 QUANTITATIVE MEASUREMENTS. 

QUESTIONS AND EXERCISES. 

On what general principles are thermometers constructed? — What ma- 
terial is employed in making thermometers? — Why is mercury selected 
as a thermometric indicator ? — Describe the manufacture of a mercurial 
thermometer. — How are thermometers graduated ? — State the boiling- 
points of alcohol, chloroform, ether, mercury, and water on either ther- 
mometric scale. — Describe the details of manipulation in determining the 
melting-points of solids. — In what respect do pyrometers differ from 
thermometers? — Mention the melting-points of glacial acetic acid, oil of 
theobroma, lard, suet, and wax. — Give the fusing-points of tin, lead, zinc, 
copper, and cast iron. 



Weight. 

The Balance. — The balance used in the quantitative operations 
of chemistry must be accurate and sensitive. The points of sus- 
pension of the beam and pan should be polished steel or agate 
knife-edges, working on agate planes. It should turn easily 
and quickly, without too much oscillation, to gi^ or ^^^ of a 
grain, or ^ of a milligramme, when 1000 grains, or 50 or 60 
grammes, are placed in each pan. (Grammes are weights of the 
metric system, a description of which is given on pages 40-43). 
The beam should be light but strong, capable of supporting a 
load of 1500 grains or 100 grammes; its oscillations are observed 
by help of a long index attached to its centre, and continued 
downward for some distance in front of the supporting pillar of 
the balance. The instrument should be provided with screws for 
purposes of adjustment, a mechanical contrivance for supporting 
the beam above its bearings when not in use or during the 
removal or addition of weights, spirit-levels to enable the oper- 
ator to place the balance in a horizontal position, and the whole 
should be enclosed in a glass case to protect it from dust. It 
should be placed in a room the atmosphere of which is not liable 
to be contaminated by acid fumes, and in a situation as free as 
possible from vibration. During weighing, the doors of the 
balance-case should be shut, in order that currents of air may 
not unequally influence the pans. 

The Weights. — These should be preserved in a box having a 
separate compartment for each weight. A weight should not be 
lifted directly with the fingers, but by the aid of a small pair of 
forceps. If grain-weights, they should range from 1000 grains 
to y^Q grain, with a ^^ made of gold wire to act as a '' rider" on 
the divided beam, and thus indicate by its position lOOths and 
lOOOths of a grain. From y\y to 10 grains the weights may be of 
platinum or aluminium ; thence upward to 1000 grains of gilt or 
platinized brass. The relation of the weights to each other should 
be decimal. Metric decimal weights may range from 100 grammes 
to 1 gramme of gilt or platinized brass, and thence down- 



SPECIAL GRAVITY. 



599 



ward to 1 centigramme, of platinum or aluminium, a gold centi- 
gramme rider being employed to indicate milligrammes and tenths 
of a milligramme. 

Specific Gravity or Relative Density. 

The specific gravity, or relative density, of a substance is the 
ratio of its weights to that of an equal volume of a standard sub- 
stance. This comparative heaviness in the case of solids and 
liquids is conventionally expressed in relation to water : they are 
considered as being lighter or heavier than water. Thus, water 
being regarded as unity =1, the relative density, or specific grav- 
ity, of ether is represented by the figures 0.716 (it is less than 
three-fourths, 0.750, the weight of water), oil of vitriol by 1.826 
(it is nearly twice, 2.000, as heavy as water). The specific gravi- 
ties of substances are, morever, the weights of similar volumes at 
25° C. (77° F.); for the weight of a definite volume of any sub- 
stance varies according to temperature, becoming, as a rule, 
heavier when cooled and lighter when heated, diff'erent substances 
(gases excepted) differing in the extent to which they contract 
and expand. While, then, specific gravity is, truly, the com- 
parative weight of equal bulks, the numbers which, in the United 
States, commonly represent specific gravities are the comparative 
weights of equal bulks at 25° C. (77° F.), water being taken as 
unity. ^ The standard of comparison for gases was formerly air, 
but is now usually hydrogen. 

Specific Gravity of Liquids. 

Procure any small bottle holding from 100 to 1000 grains, 
and having a narrow neck ; counterpoise it in a delicate bal- 
ance ; fill it to about half-way up the neck with pure distilled 
water having a temperature of 25° C. (77° F.); ascertain the 
weight of the water, and, for convenience, add or subtract a 
drop or two, so that the weight shall be a round number of 
grains ; mark the neck by the aid of a diamond or file-point 
at the level of the lower edge of the curved surface of the 
water. Consecutively fill up the bottle to this neckmark with 
several other liquids, cooled or warmed to 25° C. (77° F.), 
first rinsing out the bottle once or twice with a small quantity 
of each liquid, and note the weights ; the respective figures 



^ The true weight of a substance is its weight in air plus the weight of 
an equal volume of air and minus the Areight of a vohime of air equal to 
the vohuiae of tlie brass or other weights emph^yed ; or, in otlier words, 
its weight in vacuo, uninfluenced hy the buoyancy of the air ; but such a 
correction of the weight of a substance is seldom necessary, or, indeed, 
desirable. 



600 QUANTITATIVE MEASUREMENTS 

represent the relative weights of equal volumes of the liquids. 
If the capacity of the bottle is 100, or 1000 grains, the result- 
ing weights will, without calculation, show the specific gravi- 
ties of the liquids ; if any other number, a simple calculation 
must be worked out to ascertain the weight of the liquids as com- 
pared with 1 (or 1.000) of water. Bottles conveniently ad- 

Firr. 63. Fig. 64. Fig. 65. Fig. 66. 




Specific gravity bottles. 

justed to contain 250, 500, or 1000 grains, or 50 or 100 
grammes water, w^hen filled to the top of their perforated stopper 
(Fig. Qb), and other forms of the instrument, are sold by all 
chemical-apparatus makers. Fig. 66 is that of a bottle 
extremely useful in ascertaining the specific gravities of the 
volatile liquids. 

Verify some of the following stated specific gravities of official 
liquids : — 

Acid, acetic •••.,.. 1.045 

'' diluted 1.009 

" glacial 1.049 

" hydrochloric 1.158 

" '" diluted 1.049 

" nitric • • • 1.403 

" diluted ■ 1.054 

" phosphoric, diluted 1.057 

" sulphuric 1.826 

" " aromatic 0.933 

" diluted . .^ 1.067 

'' sulphurous, solution of 1.028 

Alcohol, absolute (real) 0.790 

(official) 0.794 to 0.7969 

(92.3 percent.) 0.816 

(41.5 " )...••• 0.936 

Ammonia, aromatic spirit of 0.900 

water 0.958 

" water, stronger 0.897 

Benzole 0.871 

Chloroform 1.476 

Creosote not below 1.072 



SPECIAL GRAVITY. 



601 



Ether 0.716 to 0.717 

" spirit of nitrous 0.823 

Glycerin 1.246 

Ferric chloride, solution of 1.305 

" sulphate, " 1.432 

Lead subacetate, " 1.235 

Lime, syrup of ■ ' 1.145 

Mercury (at 0° C.=32° F.) 13.596 

(at25°C. =77°F.) 13.535 

" nitrate, solution of (about) 2.086 

Oil of eucalyptus 0.905 to 0.925 

" mustard 0.013 to 1.020 

" sandal wood 0.965 to 0.975 

Potassium Hydroxide, solution of 1.046 

Soda, solution of, chlorinated 1.050 

Syrup 1.313 

" of ferrous iodide 1.349 



Hydrometers, formerly termed areometers. — The specific gravity 
of liquids may be ascertained, without balance and weights, by 
means of the hydrometer — an instrument usually of glass, having 
a graduated stem and a bulb or bulbs at the lower part. The 
specific gravity of a liquid is indicated by the depth to which the 
hydrometer sinks in the liquid, the point marked 1.0 or 1000 
upon the scale indicating the depth to which it sinks in pure 
water. Hydrometers constructed for special purposes are known 
under the names of saccharometer, lactometer, elaeometer, urinom- 
eter, alcoholometer. Hydrometers require a considerable quan- 
tity of liquid fairly to float them ; and specific gravities observed 
with them are usually less delicate and trustworthy than those 
obtained by the balance, nevertheless they are exceedingly use- 
ful for many practical purposes where the employment of a deli- 
cate balance would be inadmissible. 



Specific Gravity of Solids in Mass. 

Weigh in the usual manner a piece (50 to 250 grains) of 
any solid substance heavier than water. Then weigh it in 
water, by suspending it from" a shortened balance-pan by a 
fine hair or filament of silk and immersing in a vessel of water 
(Fig. 67). The buoyant properties of the water will cause the 
solid apparently to lose weight ; this loss in weight is the 
exact weight of a volume of water equal to the volume of the 
immersed object. The weight of the substance and the weight 
of an equal volume of water being thus ascertained, a simple 
calculation gives the relative weight of the substance, as com- 
pared with water--1.000. Divide the weight in air bv the 



602 QUANTITATIVE MEASUREMENTS. 



lo^^ofwei-htinwater, the resulting number is the specific 
gravity in^elation to 1 part of water, the conventional stand- 
ard of comparison. 



Fig. 




Weighiug a solid iu water. 



Verify some of the following specific gravities :— 

. . . 2.56 

Albumin qji 

Antimony 9 §3 

Bismuth . . . • • ; • ; 17 69 

Coins, English, gold -j^q 3q 

" " silver gV^ 

" " bronze g'g^ 

Copper ' ; ■ 19134 

Odd , 7,84 

lion 11.36 

Lead 1,74 

Magnesium 2.70 

Marble * ^ 1,82 

Phosphorus 21*53 

Platinum ' ; io;53 

Silver 2.05 

Sulphur _ 729 

Tin ' ; ; 7;i4 

Zinc 

specific gravities of solid ^^^^^^^^^^r^:!^ 

adhrr"ngai,-bubbles must be carefully removed; the substance 
must be quite insoluble m water. 



SPECIFIC GRAVITY. 603 

Specific Gravity of Solids in Powder or Small 
Fragments. 

Weigh the particles ; place them in a counterpoised specific- 
gravity bottle of known capacity, and fill up with water, 
taking care that the substance is thoroughly wetted ; again 
weigh. From the combined weights of water and substance 
subtract the amount due to the substance : the residue is the 
weight of the water. Subtract this weight of water from the 
quantity which the bottle normally contains : the residue is 
the amount of water displaced by the substance. Having thus 
obtained the weights of equal volumes of water and substance, 
the specific gravity of the latter, as compared with water = 
1.000, is obtained by dividing the weight of the substance by 
the weight of the water. 

Or, suspend a cup, short glass tube, or bucket from a 
shortened balance-pan ; immerse in water ; counterpoise ; place 
the weighed powder in the cup, and proceed as directed for 
taking the specific gravity of a solid in mass. 

This operation may be conducted on fragments of any of the 
substances the specific gravities of which are given in the foregoing 
Table, or on the powdered piece of marble the specific gravity of 
which has been taken in mass. The specific gravity of one piece 
of glass, first in mass, then in powder, may be ascertained ; the 
results should be identical. The specific gravity of shot is about 
11.350 ; sand 2.600 ; mercury, 13.535. 

Specific Gravity of Solids Soluble in Water. 

Weigh a piece of sugar or other substance soluble in water ; 
then suspend it from a balance in the usual manner, and 
weigh it in turpentine, benzol, or petroleum, the specific 
gravity of which is known or has been previously determined; 
the loss in weight is the weight of an equal volume of the 
turpentine, i.e., it is the weight of the turpentine displaced l)y 
the substance. Ascertain the weight of an equal volume of 
water by calculation : — 

Sp. gr. of . sp. gr. of . . weight of tnrpen- . weight of an equal 
turpentine ' water " ' tine displaced ' volume of water. 

The exact weights of equal volumes of sugar and water having 
been obtained, the specific gravity of sugar, as compared with 
water = 1.000 is obtained by calculation. Divide the weight 
of the sugar by that of the equal volume of water, the quotient 



604 QUANTITATIVE MEASUREMENTS. 

is the specific gravity of sugar. The specific gravity of sugar 
ranofes from 1.590 to 1.607. 



Specific Gravity of Solids Lighter than Water. 

This is obtained in a manner similar to that for solids 
heavier than water ; but the light substance is sunk by attach- 
ing it to a piece of heavy metal, the weight of water which the 
latter displaces being deducted from the weight displaced by 
both ; the remainder is the weight of a quantity of water equal 
in volume to the light substance. For instance, a piece of wood 
weighing 12 grammes (or grains — for it is assumed that the stu- 
dent works equally w^ell with metric as with imperial weights) 
is tied to a piece of metal weighing 22 grammes, the loss of 
weight of the metal in water previously having been found to 
be 3 grammes. The two, weighing 34 grammes, are now im- 
mersed, and the loss in weight is found to be 26 grammes. 
But of this loss 3 grammes have been proved to be due to the 
buoyant action of the water on the metal; the remaining 23, 
therefore, represent the same effect on the wood ; 23 and 12, 
therefore, represent the weights of equal volumes of water and 
of the wood, and 23 : 12 : : 1 : 0.5217. Or, shortly, as before, 
divide the weight of the wood in air by the weight of an equal 
volume of water; 0.5217 is the specific gravity of the wood. 
Another specimen of wood may be found to be three-fourths 
(0.750) the weight of water, and others heavier. Cork varies 
from 0.100 to 0.300. 

The specific gravity of a very minute quantity of a heavy or 
light substance may be ascertained by noting the specific gravity 
of a fluid in which it, being insoluble, neither sinks nor swims ; 
or by immersing it in a weighed piece of paraffin whose specific 
gravity is known, noting the specific gravity of the whole, and 
correcting for the infiuence of the paraffin. 

Specific Gravity of Gases. 

The determination is analogous to that in the case of liquids. 
A globe exhausted of air and holding from 1 to 4 litres (or quarts) 
is suspended from the arm of a balance, and counterpoised by a 
similar flask. Gases are introduced in succession and their weights 
noted. By calculation their specific gravities are obtained in 
relation to air or hydrogen, whichever is taken as a standard. 

Correction of ihe Volume of Gases for Pressure. — The height of 
the barometer at the time of manipulation is noted. Remember- 



SPECIFIC GRAVITY, 605 

ing that the volume which a gas occupies varies inversely as the 
pressure to which it is subjected (Boyle's Law, p. 46), a simple 
calculation shows the volume which the gas would occupy at 760 
millimetres (or 29.92 inches), the standard pressure. Thus 40 
volumes of a gas at 740 millimetres pressure are reduced to 39 
when the pressure becomes 760 millimetres (or 90 vols, at 29 inches 
pressure becomes 87 vols, at 30 inches). 

Connection of the Volume of Gases for Temperature. — This is done 
in order to ascertain what volume the gas would occupy at 32° F. 
(0° C). Gases are equally affected by equal variations in temper- 
ature (Charles). They expand about 0. 3665^ percent, (ays) of 
their volume at the freezing-point of water for every C. degree 
(0.2036 percent., or^^^^ for every F. degree) that their temperature 
is raised above that point (see Charles's Law, p. 46). Thus 8 
volumes of gas at 0° C. will become 8.293 at 10° C ; for if 100 
become 103.665 on being increased in temperature 10° C, 8 will 
become 8.293 (or if 100 become 102. 036 on being increased 10° F., 
8 will become 8.163. 

Vapor- density. — Vapors are those gases which condense to liquids 
at ordinary temperatures. What is commonly called the vapor- 
density of a substance is really the specific gravity or relative den- 
sity of its vapor, and is simply the ratio of the weight of any given 
volume to that of a similar volume of air or hydrogen at the same 
temperature and pressure. But, for convenience of comparison, 
this experimental specific gravity is referred, by calculation asjust 
described for permanent gases, to a temperature of 0° C, and 760 
millimetres pressure. A teaspoonful or so of liquid is placed in a 
weighed flask about the capacity of a common tumbler and having 
a capillary neck: the flask is immersed in an oil-bath and heated to a 
temperature considerably above the boiling-point of the liquid; at 
the moment vapor ceases to escape, the neck is sealed by a blow-pipe 
flame, and the temperature of the bath noted ; the flask is then 
removed, cooled, cleaned, and weighed ; the height of the barom- 
eter is also taken. The neck of the flask is next broken off" 
beneath the surface of water (or of mercury), which rushes in and 
fills it, and the flask is again weighed with its contents, by which 
its capacity in cubic centimetres is found. From these data the 
volume of vapor yielded by a given weight of liquid is ascertained 
by a few obvious calculations. The capacity of the globe having 
been ascertained, the weight of an equal volume of air ^ is calcu- 
lated. This weight of air is deducted from the original weight of 
the flask, which gives the true weight of the glass. The weight 

^ Corrected for the difference between the niercnrial and air-thcrmoni- 
eters, the coefficient of expansion of air is 0.003656 (Miller). The co- 
efficient of expansion of different gases varies very slightly, hcing some- 
what higher for the more liqnefiable gases. 

2 1 cubic centimetre of air at 0° C. and 760 millimetres weighs 0.001293 
gramme. 



606 QUANTITATIVE MEASUREMENTS. 

of the glass is next subtracted from the weight of the flask and 
contained vapor (now condensed), which gives the weight of 
material used in the experiment. The volume which this weight 
of material occupied at the time of experiment is next corrected 
for temperature (to 0° C. ) and pressure (760 millimetres) in the 
manner just described. The weight of a similar volume of hydro- 
gen is next found. ^ The weights of equal volumes of hydro- 
gen and vapor being thus determined, the density of the vapor, as 
compared with that of hydrogen = 1, is easily calculated. This 
l)rocess of finding the weight of a given volume of vapor was in- 
troduced by Dumas. Gay-Lussac' s method consists in determin- 
ing the volume of a given weight : it has been improved by Hof- 
mann. An easy and excellent method by V. and C. Meyer con- 
sists, like that of Gay-Lussac, in determining the volume of the 
A^apor of a given weight of a fluid or solid, but difliers from it in 
so far that the volume of the vapor is ascertained by measuring 
an equal volume of air which the vapor is made to displace. 

As this method is the one which is now most commonly em- 
ployed a somewhat detailed description of it may be given here. 

Vapot'-densify Determination by Meyer^ s Method. — The special 
form of apparatus employed is represented in Fig. 68, and con- 
sists essentially of the three following parts : — 1. The inner ves- 
sel a, which is really a flask having an elongated body, a verj^ 
long narrow neck, and a nearly capillary side delivery-tube b ; 
2. The outer jacketing vessel/, which also is a flask of special 
shape; and 3. The measuring apparatus. In order to carry out 
a vapor-density determination, a suitable liquid, of boiling-point 
considerably higher than that of the substance under examination, 
is placed in the outer vessel and is there heated until it is in 
brisk ebullition and its vapor is condensing close to the top of the 
vessel. By this means the greater part of the inner vessel is 
surrounded by a jacket of hot vapor and is thereby raised to a 
practically uniform temperature. Prior to this preliminaiy heat- 
ing operation, the outlet end of the delivery-tube b has been 
placed beneath the water in the vessel d, and, owing to the ex- 
pansion of the air enclosed in a, bubbles make their escape at 
the surface of the water. During the heating, a weighed 
quantity of the substance to be examined (contained in a veiy 
small stoppered bulb) is suspended in the widened upper portion 



1 1 litre (1000 cubic centimetres) of hydrogen at 0° C. and 760 milli- 
metres (the barometer being at 0° C.) weighs 0.09 gramme. 100 cubic 
inches of hydrogen at 32° F. weigh 2.265 grains ; at 60° F. 2.143 grains (the 
barometer being 30 inches at 60° F. in both cases). 100 cubic inches of 
air at 32° F. weigh 32.698 grains ; at 60° F., 30.935 (barom. 30 inches at 60° 
F.). 1 cubic inch of water weighs 252.458 grains (Chancey, 252,279) at 
62° F., and 30 inches. 1 gallon of water contains 277i (277.274 at 620 F.) 
cubic inches. 1 cubic foot contains about 6i gallons. 



SPECIFIC GRAVITY. 



607 



Fig. 68. 




of the inner vessel, just below the stopper c which, when replaced, 
closes the mouth of the vessel. As soon as bubbles no longer 
escape from 6, the apparatus is ready for an experiment. The 
tubee, previously filled with water, is next inverted over the outlet 
end of b and then, by aid of a wire which 
passes, air-tight, through the stopper c, the 
bulb containing the substance is released, 
and falls to g, where a thin layer of asbestos 
has previously been placed to prevent its 
cracking the glass of the inner vessel. As 
a result of the high temperature at g, the 
stopper of the bulb is forced out and the 
whole of the liquid gradually becomes con- 
verted into vapor (which should not more 
than half fill the lower part of a). This 
vapor drives out of a, and into the measur- 
ing-tube, a quantity of air equal in volume 
to that which itself occupies. 

At the close of the experiment, the vol- 
ume of the air in the measuring-tube is 
read off and reduced to standard tempera- 
ture and pressure. The corrected volume 
represents, theoretically, the space which the 
weighed quantity of substance would occupy 
if it existed as vapor under normal conditions 
of temperature and pressure. From the 
results thus obtained, a simple calculation 
gives the vapor- density. 

Determinations of the specific gravities 
or relative densities of gases, and of the 
vapor-densities of liquids (or of vaporiz- 
able solids), are carried out for the purpose 
of fixing the molecular weights of these 
various substances in the state of gas or 
vapor, and of assigning to them molecular 
formulae. As already explained in the 
Section on the General Principles of Chem- 
ical Philosophy, the relative molecular 
weights of substances in the gaseous state 
are proportional to their relative densities 
{see pp. 54, 55). The molecular weight of 
h/drogen is chosen=2 as standard for the 
comparison of the molecular weights of 

other substances in the gaseous state ; but since the relative molecular 
weight and the relative density of each substance are }iroportional 
to each other, it follows that the number representing luiy molec- 
ular weight, in terms of the standard just mentioned (hydrogen 
= 2), may be obtained by doubling the number representing the 



Meyer's vapor-density 
apparatus. 



608 QUANTITATIVE MEASUREMENTS. 

relative density. The molecular weight of a substance thus hav- 
ing been ascertained, and the quantitative composition and em- 
pirical formula also having been determined [see p. 60), the molec- 
ular formula can be assigned. The quantitative value of any 
molecular formula must agree with the experimentally determined 
molecular weight of the substance which it purports to represent. 
Thus the determination of the quantitative composition of ben- 
zene and the necessary calculation lead to the emj^irical formula 
CH. But this formula would represent a substance of molecular 

12.91 
weight 12.91, or of density (as vapor) — '^ — ^6.455, whereas the 

molecular weight of benzene as ascertained by doubling the 
number representing its vapor density is 77.46 {i.e., 38.73X2). 
The only formula which corresjDonds to this molecular weight, as 
deduced fi'om the vapor-density, is CgHg, and this, accordingly, 
is assumed as the molecular formula for benzene. 



QUESTIONS AND EXEECISES. 



What is meant by the specific gravity or relative density of a substance? 
— In speaking of light and heavy bodies specifically, what standard of 
comparison is conventionally employed ? — How are specific gravities ex- 
pressed in figures ? — Why should specific gravities be taken at one con- 
stant temperature? — How does the buoyancy of air afiect the apparent 
weight of any material as ascertained by aid of the balance? — Give 
a direct method for taking the specific gravity of liquids. — A certain 
bottle holds 150 parts, by weight, of water, or 135.7 of diluted alcohol ; 
show that the specific gravity of the latter is 0.9046. — An imperial fluid 
ounce of a liquid weighs 366J grains ; prove that its specific gravity is 
0.838. — Equal volumes of benzole and glycerin weigh 34 and 49 grammes 
respectively, and the specific gravity of the benzole is 0.850; show that 
the specific gravity of the glycerin is 1.225. — Explain the process em- 
ployed in taking the specific gravities of solid substances in ma.ss and in 
powder.— State the method by which the specific gravity of a light body, 
such as cork, is obtained.— What modifications of the usual method are 
necessary in ascertaining the specific gravities of substances soluble in 
water? — How are the specific gravities of gases determined? — What are 
vapor-densities? — Describe Meyer's vapor-density apparatus. — By what 
law can the volume of a gas, at any required pressure, be deduced from 
its ob.served volume at another pressure? — To what extent will 78 vol- 
umes of a gas at 29.3 inches bai-ometric pressure alter in volume when the 
pressure is 30.2 inches? — Write a short account of the means by which 
the volumes of gases are corrected for temperature. — At the temperature 
of 15° C. 40 litres of a gas are measured. To what volume will this gas 
contract on being cooled to the freezing-point of water (0° C. ) ? — Answer, 
37.916 litres. 



Memorandum. — The next subjects of experimental study 
will be determined by the nature of the student's future pur- 



Q UANTITA TIVE ANAL YSIS. 



609 



suits. In most cases the operation^ of quantitative analysis 
will engage attention. These should include both volumetric 
and gravimetric determinations ; and some details concerning 
both of these modes of marking determinations are given in 
the following pages. 



QUANTITATIVE ANALYSIS. 



INTRODUCTORY REMARKS. 

GeMeral Principles. — The proportions in which chemical 
substances unite wdth each other in forming compounds are 
definite and invariable (p. 50). Quantitative analysis is 
based on this law. When, for example, aqueous solutions of a 
silver salt and a chloride are mixed, a white curdy precipitate 
is produced containing chlorine and silver in atomic propor- 
tions — that is, 35.18 parts of chlorine to 107.12 of silver. No 
matter w hat the chloride or what the silver salt, the resulting 
silver chloride is invariable in composition. The formula 
AgCl is a convenient symbolic representation of this compound 
in these proportions. In the case of any known weight of a 
compound, of which the quantitative composition has been 
determined previously, the quantities of its constituents 
can be ascertained by simple calculation. Suppose, for 
instance, 8.53 parts of silver chloride have been obtained 
in some analytical operation : this quantity will be found 
by calculation to contain 2.109 parts of chlorine and 
6.421 of silver. For if 142.3 (the formula weight) of silver 
chloride contain 35.18 (the atomic weight) of chlorine, 8.53 

35.18X8.53 
142.3 
chlorine; and if 142.3 of silver chloride contain 107.12 of 

Q^Q ^ -1 11 -^ -11 . • 107.12X8.53 . ,,^. 
silver, 8.53 of silver chloride w^ill contain ^tto"^^ =b.4il 

of silver. To ascertain, for example, the quantity of silver 
in a substance containing, say, silver nitrate, all that is neces- 
sary is to take a weighed quantity of the substance, dissolve 
it, precipitate the whole of the silver by adding hydrochloric 
acid or other soluble chloride until silver chloride is no longer 
produced, collect the precipitate on a filter, wash, dry, and 
39 



of silver chloride will contain 



:2.109 of 



610 QUANTITATIVE ANALYSIS. 

weigh. The quantity of silver in the dried chloride, ascer- 
tained by calculation, is the quantity of silver in the weighed 
portion of substance on which the operation was conducted ; a 
further simple calculation gives the quantity percent. — the 
form in which the results of quantitative analysis are usually 
stated. Occasionally a constituent of a substance admits of 
being isolated and weighed in the uncombined state. Thus 
the quantity of mercury in a substance may be determined 
by separating and weighing the mercury in the metallic con- 
dition ; if the substance under examination be calomel (HgCl) 
or corrosive sublimate (HgClg), the proportion of chlorine may 
then be ascertained by calculation (Hg=198.5 ; 01^35.18), 
or a chlorine determination may be made. 

Nature of Gravimetric Quantitative Analysis. — As stated above, 
an element may sometimes be isolated and weighed and its quantity 
thus ascertained ; or it may be separated and weighed in combi- 
nation Avith another element whose combining proportion is well 
known ; this is quantitative analysis by the gravimetric method. 

Nature of Volumetric Quantitative Analysis. — Volumetric opera- 
tions depend for success on some accurate initial gravimetric opera- 
tion. A loeighed quantity of a pure salt is dissolved in water or 
other fluid, and the solution is made up to a definite volume so as to 
obtain a standard solution. Quantitative analysis by the volu- 
metric method consists in ascertaining the A'olume of the standard 
liquid which must be added to the substance under examination 
before a given effect is produced. Thus, for instance, a solution 
of silver nitrate of known strength may be used in experimentally 
determining an unknown quantity of a chloride in any substance. 
The silver solution is added to a solution of a definite quantity of 
the substance until flocks of silver chloride are no longer precipi- 
tated: every 107.12 parts of silver added (or 168.69 of silver 
nitrate) indicate the presence of 35.18 of chlorine, or an equiva- 
lent quantity of any chloride. The preparation of a standard 
solution, such as that of the silver nitrate to which allusion is 
here made, requires much care; but once it is prepared, certain 
analyses can, as already indicated, be executed with far greater 
rapidity and ease than by gravimetric processes. 

In the following pages an outline of volumetric and gravimetric 
quantitative analysis is given. The scope of this work precludes 
any attempt to describe all the little mechanical details observed 
by quantitative analysts; essential operations, however, are so fully 
treated that careful manipulators will meet with little difiiculty. 



VOLUMETRIC ANALYSIS. 611 



VOLUMETRIC ANALYSIS. 

Preliminary Note. — Great care should be observed in 
selecting a fair sample of any bulk of material that is to be 
examined either by volumetric or gravimetric analysis. If the 
whole quantity is in separate parcels, and if there is any ground 
for believing that the parcels differ in quality, they should, 
if practicable, be carefully mixed, or, technically, " bulked." 
Small portions should be taken from different parts of the 
resulting heap and well mixed in a mortar or other vessel, 
or, in certain cases, dissolved, and the solution well stirred or 
shaken. A specimen of the powder, or a portion of the solu- 
tion, may then be selected for analysis. 

Introduction. — The operations of volumetric analysis con- 
sist {a) in carrying out some definite chemical reaction, already 
well known to the operator, with (6) definite quantities of sub- 
stances or salts; (c) the exact termination of the reaction between 
the two salts or substances being ascertained — usually by some 
chemical indicator (litmus, starch, etc.). A portion of the sub- 
stance to be tested is carefully weighed and dissolved. To this 
solution there is gradually added the second substance contained 
in the testing fluid, commonly termed the Standard Volumetric 
Solution. The usefulness, and indeed the preparation, of this 
Standard Solution is founded (as already indicated on page 610) 
on some accurate initial gravimetric operation. A weighed quantity 
of a pure salt is dissolved in water, and the solution is made up 
to a definite volume so as to obtain a Standard Volumetric Solu- 
tion. Accurately measured volumes of such a Standard Volumet- 
ric Solution will obviously contain just as definite quantities of 
the dissolved salt as if those quantities were weighed in a balance; 
and as measuring occupies less time than weighing, the volumetric 
operations can be conducted with great economy of time as com- 
pared with the corresponding gravimetric operations. K standard 
solution is one containing a known quantity of substance in unit 
volume. 

A normal solution is a solution one litre of w^hich represents, 
more or less directly, the chemical value or activity of the atomic 
weight of hydrogen taken in grammes (H = l, that is, 1 gramme). 
A tenth-normal solution is one-tenth the strength of a normal solu- 
tion. A hundredth-normal solution is one-hundredth the strength 
of a normal solution. The normal solution of iodine (H = l, 
1 = 125.9) would contain 125.9 grammes of iodine per litre; that 
quantity being capable of displacing, or otherwise being equal in 
chemical activity to, 1 gramme of hydrogen. The ofUcial Volu- 



612 VOLUMETRIC ANALYSIS. 

metric Solution of Iodine containing 12.59 grammes per litre, is a 
tenth-normal solution. The official Volumetric Solution of Silver 
Nitrate containing 16.869 grammes of the salt in one litre 
(AgXOg = 168.69 -^- 10), is a tenth-normal solution. The offi- 
cial Volumetric Solutions of Sodium Hydroxide (NaOH = 39.76 
grammes per litre), and Sulphuric Acid (HgSO^ =97.35 -^ 2, 
that is, 48. 675 grammes per litre), are normal solutions. Solutions 
of hydrochloric acid containing 36.18 grammes of hydrogen 
chloride (HCl = 36. 18) per litre; of oxalic acid containing 62.55 
grammes of crystallized oxalic acid (H2C20^, 2H20=125. 10 h- 2) 
per litre; and of phosphoric acid containing 32.43 grammes of 
hydrogen phosphate (H3P0^= 97.29 -^ 3) per litre, would be 
normal solutions. The molecule of potassium bichromate 
(KjCrgO, = 292. 28) in presence of an acid, yields three atoms of 
oxygen available for direct oxidation, or for union with six atoms 
of hydrogen, therefore a solution of 48.71 grammes (292.28 -f- 6) 
per litre w^ould be a normal solution. The official Volumetric 
Solution of Potassium Bichromate contains one-tenth of this 
quantity, and is, therefore, a tenth-normal solution. The official 
Volumetric Solution of Sodium Thiosulphate is tenth-normal, for 
the molecular weight in grammes (Na.^S^Og, 5H20=246.46) loses 
one atomic weight of sodium in grammes (]S"a=22. 88) when 
attacked by one atomic weight of iodine in grammes (1=125,9), 
a quantity equal in chemical value or activity to the atomic weight 
of hydrogen in grammes (H=l); and as the official Thiosulphate 
Solution, like the official Iodine Solution, contains only one-tenth 
of that hydrogen equivalent in grammes, it is a tenth-normal 
solution. 



Apparatus. 

The only special vessels necessary in volumetric quantitative 
operations are: — 1. A one-litre flask (Fig. 69) which, when filled 
to a mark on the neck, contains one litre (1000 cubic centimetres, or 
rather 1000 grammes (of water ^) ; it serves for preparing solutions 
in quantities of one litre. 2. A tall cylindrical graduated jar 
(Fig. 70) which, filled to the highest graduation, contains 1000 
grammes of distilled water divided into 100 equal parts; it serves 
for the measurement and admixture of decimal or centesimal parts 
of the litre. 3. A graduated tube or burette (Fig. 71), the marked 
portion of which, when filled to" 0," holds 100 grammes of distilled 
water, and is divided into 100 equal parts, or 50 grammes and 
divided into equal parts, each of which is taken as corresponding 

1 A cubic centimetre 13 the volume occupied by one gramme of distilled 
water at its point of greatest density, namely, 4°C. Metric measure- 
ments, however, are officially taken at 25° C. (77° F.). 



APPARATUS. 



613 



to 1 cubic centimetre, with subdivisions, each subdivision being 
further subdivided; it is used for accurately measuring small 
volumes of liquids. A stopcock is fitted to the contracted portion, 
or other modes of arresting the flow of liquid may be adopted. 

The accurate reading of the height of a solution in the burette 
is a matter of great importance ; it should be taken from the 
bottom of the curved surface, or meniscus, of the liquid. When 
reading the burette, the eye should be on the same level as the 
bottom of the meniscus. In the case of a colored solution, when 
the bottom of the meniscus cannot be clearly seen, the reading 
must be taken from the surface of the liquid. 



Fig. 69. 



Fig. 70 




A litre jar. 



A litre flask. 



A burette, etc. 



Occasionally a hollow glass float or bulb (Erdmann's float, see 
Fig. 71) is employed, of such a width that it can move freely in the 
tube without undue friction, and so adjusted in weight that it shall 
sink to more than half its length in any ordinary liquid. A fine 
line is scratched around the centre of the float ; this line must 
always be regarded as marking the height of the fluid in the 
burette. In charging the burette, a solution is poured in, not 
until its surface is coincident with 0, but until the mark on the 
float is coincident with 0. 

The exercises in Volumetric Analysis described in the following 
pa^es are illustrative only and do not deal exhaustively with the 
application of volumetric methods to all the chemical substances 
employed in pharmacy. Volumetric methods, as applied to ofli- 
cial substances, are fully described in the IT. S. Pharmaoojxvia, 
and for fiirther information respecting them the student is referred 
to that work. 



614 VOLUMETRIC ANALYSIS. 



DETERMINATION OF ALKALIES. 

Volumetric Solution of Sulphuric Acid. 
(Sulphuric Acid, H^^O^ 97.35.) 

The Sulphuric radical, being bivalent, and most of the metals 
contained in the salts which are determined by means of standard 
sulphuric acid solution being univalent, it is convenient that each 
litre of this solution should contain half a molecular weight (the 
hydrogen equivalent), in grammes, of the acid (HgSO^ = 97.35, 
and 97.35 -f- 2= 48.675). A solution of this strength is a normal 
solution. 

As it is not always easy to obtain pure sulphuric acid, the 
solution may be made from the commercial acid by mixing 50 
grammes with five or six times its volume of water and after 
cooling adding sufficient water to make a litre of solution. The 
exact quantity of acid present in this solution may then be deter- 
mined by titration with pure sodium carbonate, making use of the 
following memoranda: — 

Na^COg + H^SO, = Na,SO, + CO^ + H^O 

2)105.31 2) 97.35 
52.655 48.675 

Pure anhydrous sodium carbonate can be prepared readily, for ^_ 
commercial bicarbonate is usually of such purity that when a ^M 
small quantity is heated to redness for a quarter of an hour, ^B 
the resulting carbonate is practically free from impurity. The 
bicarbonate should, however, be tested, and if more than traces 
of chlorides and sulphates are present, these may be removed by 
washing a few hundred grammes, first with a saturated solution of 
sodium bicarbonate, and afterward with pure distilled water. 
After drying, the salt is ready for ignition — a few grammes in a 
small crucible. 

About half a gramme of the sodium carbonate is accurately 
weighed and placed in a half-pint flask, around the neck of which 
twine has been wound to protect the fingers when the heated vessel 
is shaken by the operator (page 116). The salt is dissolved in 
water to about one-third the capacity of the flask, and a few drops 
of the indicator, blue solution of litmus, are added. The acid 
solution to be " standardized" is then poured into a burette and 
run therefrom into the flask until the reddened litmus indicates the 
presence of a free acid. This will be due in the first place to car- 
bonic acid liberated and remaining dissolved in the solution; 
hence the contents of the flask must be gently boiled for several 
minutes to expel carbonic anhydride, when the blue color will 



6 




VOLUMETRIC DETERMINATL 

have returned. More acid is then run in until the mixture' after 
boiling, remains of a neutral color, indicating that just enough 
acid has been added to complete the reaction expressed in the 
foregoing equation. 

Let it be supposed that 0.6 gramme of sodium carbonate was 
taken, and that this required 11 Cc. of sulphuric acid solution, 
how many Cc. of this solution would contain 48. 675 grammes of 
pure sulphuric acid; or, what is equivalent in the reaction, how 
many Cc. would be required to neutralize 52.65 grammes of 
sodium carbonate? By rule of three, 0.6 : 11 :: 52.65 : x, 
and X = 965.25 ; therefore in the example taken 965.25 Cc. are 
equivalent to 52.65 grammes of sodium carbonate, and contain 
48. 675 grammes of sulphuric acid. 

This solution may be diluted with water, every 965.25 Cc. to be 
diluted to 1000 Cc, so that 1000 Cc. shall contain 48.675 
grammes of sulphuric acid, or it may be used as it is and the 
necessary correction applied. 

Borax, purified by recrystallization, is recommended by Kim- 
bach for standardizing acids, in place of sodium carbonate. 
When it is used, the indicator employed should be methyl orange, 
which is not affected by boric acid. 

The following substances may be tested conveniently by means 
of the standard solution of sulphuric acid : — 

Solutions of Ammonia. — Two or three grammes of dilute, or about 
1 gramme of stronger ammonia water, are convenient quantities to 
operate upon. The weighing is most conveniently accomplished 
by taking a small stoppered bottle containijig half an ounce or so 
of the substance, and having ascertained its total weight, trans- 
ferring about the quantity desired to the flask in which the esti- 
mation is to be conducted, and again weighing the bottle with 
what remains in it. The diiference is the exact quantity taken. 
The weighing of the ammonia solution having been accomplished, 
water is added, to about one-third the capacity of the flask (or, 
better, the ammonia is added to water already in the flask), and 
a few drops of solution of litmus are introduced. The titration is 
then conducted as described before, except that no heat is 
employed. 

2NH,0H + H^SO, = (NHJ^SO, + 2H.p 

2 )69.62 2)97.35 

34. 81 48. 675=grammos in 1000 Cc. of normal solution. 

2NH3 + H^SO, = (NHJ^SO, 

2)33^86 2)97.35 

16.93 48. 675=grammes in 1000 Cc. of normal solution. 



616 VOLUMETRIC ANALYSIS. 

1000 Cc of normal solution, or its equivalent of a solution of 
any other concentration, would, according to this equation, neu- 
tralize 16.93 grammes of ammonia gas.(NH3) or 34.82 grammes 
of ammonium hydroxide (NH^OH). If 3 grammes of ammonia 
solution had been taken, and it had required 15 Cc. of normal 
sulphuric acid solution, then the quantity of ammonia gas or 
ammonium hydroxide it contained would be seen by the following 
calculations: — 

1000 Cc. : 16.93 g. NH3 : : 15 Cc. : a: = .254 grammes NHg 
1000 Cc. : 34.81 g. NH4OH : : 15 Cc. : x = .522 grammes NH.OH 

Three grammes, then, would contain . 254 grammes of the gas, or 
.522 grammes of ammonium hydroxide. Or in percentages: — 

3 g. sol. : .254 g. NH3 : : 100 g. sol. : x g. NH3 = 8.47 ^NHg 
3 g. sol. : .522 g. NH^OH : : 100 g. sol. : x g. NH^HO = irAfo^Sii^OK 

The solution would therefore contain 8.47 percent, of ammonia 
gas (NH3) or 17.4 percent, of ammonium hydroxide (NH^OH). 
If the sulphuric acid solution was not of full standard, the number 
of Cc. which contained 48.675 grammes of sulphuric acid, which 
was, in fact, equivalent to 1000 Cc. of normal solution, might be 
substituted for 1000 Cc. in the preceding calculations. 

A comparison should now be made with the requirements of the 
Pharmacopoeia. It is useful to express results as percentage of 
substance of pharmacopoeial strength in the material examined. 
Thus the U. S. Pharmacopoeia requires ammonia water to contain 
10 percent, by weight of the gas (NH3). The solution supposed to 
have been operated on contained 8.47 per cent. NH3, therefore it 
contains 84.7 percent, of the ammonia water of the U. S. Pharma- 
copoeia.'^ 

1 Extremely minute quantities of ammonia — 1 part in many millions 
of water — may be determined volumetrically by adding excess of a color- 
less, strongly alkaline, solution of mei-curic iodide and potassium iodide, 
Mercuric Potassium Iodide Test Solution, U.S. P., or " Nessler's Reagent;" 
then in a similar vessel, containing an equal amount of pure water with 
excess of the Nessler reagent, imitating the depth of yellow or reddish- 
yellow color thus produced by adding a solution containing a known 
quantity of an ammonium salt. The quantity of ammonia thus added 
represents the quantity in the original liquid. 

The Nessler Reagent. — A litre may be made by dissolving 50 grammes 
of potassium iodide in 50 Cc. of water, adding a saturated solution 
of mercuric chloride until the precipitate of mercuric iodide remains 
undissolved even by the aid of rapid stirriug, adding 150 grammes of 
potassium hydroxide and diluting to one litre. After the precipitate has 
subsided, the clear liquid is drawn off for use, and should be preserved in 
a well-closed bottle ; the clear liquid is then decanted for use. The reacr 
tion of this Nessler test with ammonia is as follows : — 

NH3 + 2Hgl2 + 3K0H = NHg2l + 3KI + 3H2O 

Mercuric Potassium Iodide, without alkali, is commonly known as 
Mayer^s Reagent, HgKIs. A tenth-normal solution is a convenient one to 
use. 



VOLUMETRIC DETERMINATION OF ALKALIES. 617 

Stronger Ammonia water, U. S. P., contains 28 percent, by 
weight of ammonia gas (NH3). 

Note. — The calculations just described for ammonia are similar 
to those employed throughout volumetric analysis; they will not 
be repeated, therefore, in the case of every substance. 

^^ Ammonium Carbonate.'''' — The reaction indicated by the fol- 
lowing equation occurs between commercial ammonium carbonate 
and. sulphuric acid: — 

2N3H,,C,0- + 3H,S0, = 3(NHJ,S0, + 2Hp = 4C0, 



6 )312.02 6 )292.05 

52. 03 48. 675 = grammes in 1000 Cc. of normal solution. 

About 1 gramme is a convenient quantity to operate upon. 
Solution of litmus is the indicator, and the titration is conducted 
at a temperature just short of boiling. The determination is not 
very satisfactory, because the heat employed, while scarcely suffi- 
cient to expel the carbonic anhydride, is enough to occasion loss 
of ammonium salt. To avoid error, add excess of the normal acid 
solution and thus fix every trace of ammonia; then gently boil to 
get rid of carbonic anhydride; bring back the liquid to neutrality 
by an observed volume of normal alkaline solution, and deduct an 
equivalent volume of acid from the quantity first added. 

Spiritus Ammonice Aromaticus, IT. S. P. — The determination of 
ammonia in this preparation is quite analagous to its determination 
in the solutions of ammonia already described. 

Borax. — Two or three grammes is a convenient quantity. 

Na,B,O^,10H2O + H,SO, = Na,SO, + 4H3BO3 + 5Hp 

2 )379.32 2 )97.35 

189.66 48. 675 = grammes in 1000 Cc. of normal solution. 

Solution of litmus is the indicator, and the titration may be 
carried on without heat. The liberation of boric acid colors the 
litmus wine-red. This is not regarded, the titration being con- 
tinued until the bright red due to the action of free sulphuric 
makes its acid appearance. Methyl orange may be used as the 
indicator, as it is not affected by boric acid. 

Lime Water, and Syrup of Lime. — Measure about half a litre 
of lime water, or weigh about 25 grammes of the syrup. The 
following equations give quantitative expressions of the reactions: — 

Ca(0H)2 + H^SO, = CaSO, + SH^O 

2)7^.56 2) 97.35 

36. 78 48. 675 = grammes in 1000 Cc. of normal solution. 



618 



VOLUMETRIC ANALYSIS. 



Or, 



CaO 



H,SO, = CaSO, 



H,0 



2 )55.68 2 )97.35 



27.84 



48. 675 = grammes in 1000 Cc. of normal solution. 



Litmus is used as an indicator. One litre of Lime Water, 
U. S. P., contains about 1.4 gramme of calcium hydroxide, 
Ca(OH)^, equal to about 1.1 gramme of quicklime, CaO. Ten 
fluid ounces contain 6-J grains of calcium hydroxide. 

Sodium. Potassium and Sodium Hydroxides. Potassium and 
Sodium Carbonates and Bicarhonates. — Litmus is the indicator 
throughout and heat is used in all cases, for the caustic alkalies 
always contain some carbonate. 



2Na 


+ 


H,SO, = 


= H, + 


Na,SO, 


2)45.76 




2)97.35 






22.88 




48.675^ 


= grammes i 


n 1000 Cc. of normal solution 


2K0H 


+ 


H,SO, = 


= K,SO. 


+ 2HP 


2)111.48 




2)97.35 






55.74 




48.675 = 


= grammes i 


in 1000 Cc. of normal solution. 


2NaOH 


+ 


H,SO, = 


= Na^SO, 


+ 2H,0 


2)79.52 




2)97.35 







39.76 



48.675 = grammes inlOOO Cc. of normal solution. 



K^CO., 4- H^SO, + 



2 )137.27 2) 97.35 
68.635 48.675 



K^SO, + CO^ + H^O 



grammes in 1000 Cc. of normal so]uti( n 

Na^COj + H_,SO, = Na^SO, + CO^ +H,0 



2 )105.31 2 )97.35 
52.655 48.675 = 

Or, Na2C03,H20 + H^SO, = 

2) 123.1 9 2 )97.35 
61.595 48.675 
2KHCO3 4 H^SO, = 



2 )198.82 
99.41 



2)97.35 

48.675 



= grammes in 1000 Cc. of normal solution. 

Na^SO, + CO2 + llHjO 

= grammes in 1000 Cc. of normal solution 

K^SO, + 200^ + 2H2O 

= grammes in 1000 Cc. of normal solution. 



VOLUMETRIC DETERMINATION OF ALKALIES. 619 

SNaHCOg + H^SO, = Na^SO, + 200^ + ^^P 

2)166.86 2 )97.35 

83. 43 48. 675 = grammes in 1000 Cc. of normal solution. 

Convenient quantities to operate with are : of sodium, 0.4 or 
0.5 gramme, placed on 10 or 20 Cc. of water in a basin, the latter 
being immediately covered with a glass plate to preserve the face 
and hands from any caustic spurtings and to prevent loss of soda; 
of potassium hydroxide, 1 gramme; sodium hydroxide, 0.5 to 1 
gramme; potassium carbonate, or bicarbonate, 1 to 2 grammes; 
sodium carbonate, or bicarbonate, 2 to 3 grammes; dried sodium 
carbonate, 0.5 to 1 gramme; and of solutions a corresponding 
quantity. 

Potassium and Sodium Tartrates and Citrates. — When alkali- 
metal tartrates or citrates are burned in the open air, the whole 
of the metal remains in the form of carbonate. Each formula 
weight of a normal tartrate gives one formula weight of carbonate, 
and twice the formula weight of an acid tartrate gives one formula 
weight of carbonate. Advantage is taken of these reactions to 
determine indirectly the quantity of citrate or tartrate in presence 
of substances with which they are generally associated. One or 
two grammes of any of these salts is a convenient quantity to 
operate upon. The ignition may be conducted in a platinum or 
porcelain crucible. A low red heat only should be used, and the 
vessel removed when complete carbonization has been effected — 
that is to say, when nothing remains but the carbonate and free 
carbon. The mixture is then treated with hot water, and the 
carbon separated by filtration. If too little heat has been used, 
and carbonization is not complete, the filtrate will be more or less 
colored. If this should be the case, the operation must be repeated 
with a fresh quantity of material. The carbonate is titrated in the 
usual way. The following equations explain the reactions: — 

(K,C,H,0,),,H,0 + 50, = 2K,C0, + 6C0, -f 5H,0 



4 )467. 16 4 )274.54 

116.79 68.635 1 eqniv to lOOO Cc. of 

1 normal sulphuric acid sol. 

2KHC,Hp, + 50^ = K.,C03 + 700, + bYL.O 
2)373.56 2)137.27 



1 86 78 68 635 I ^^"^'^'^ *^ ^"^ ^^ ^^ 

^"- ' ^ ^^' ^""'^ \ normal sulphuric acid sol. 

2K3C,H,0, -f- 90, = 3K,C0^, + 9C0, + 5H,0 

6 )608. 4 6)411.81 

101 4 68 635 -f «^Q"iv. to 1000 Cc. of 

• ^^- ^^'\ jnormal sulphuric acid sol. 



620 VOLUMETRIC ANALYSIS. 

2jKXaC,H,Oe,4H20)+ 50^ = 2KXaC03 H ^C 



4 )560.36 4)242.58 

1 40 OQ 60 645 1 equiv. to 1000 Cc. of 

^^^' ^^ ^^' ^^^1 normal sulphuric acid sol. 

It will be readily understood that in the first (for example) of 
the reactions just represented 116.79 parts by weight of potassium 
tartrate are equivalent to 68.635 of potassium carbonate; and as 
in a previous reaction it has been shown that 68.635 parts by 
weight of potassium carbonate are equivalent to 48.675 of sul- 
phuric acid, it follows that 116.7-9 parts by weight of potassium 
tartrate are equivalent to 48. 675 of sulphuric acid. Hence 116. 79 
grammes of potassium tartrate are equivalent to 48.675 grammes 
of sulphuric acid, or to 1000 Cc. of the standard solution of 
sulphuric acid. If the substance under examination be a crude 
sample of potassium tartrate, and if the number of Cc. of sul- 
phuric acid used for 2 grammes of the sample has been 15 Cc, 
then as 1000 Cc. of the acid solution are equivalent to 116.79 
grammes of potassium tartrate, 15 Cc. of the solution are equiva- 
lent to 1.75 gramme of potassium tartrate. As 2 grammes of the 
sample contain 1.75 of real potassium tartrate, the tartrate 
examined contains 87.5 percent, of real tartrate. Commercial 
samples of this salt are practically pure as a rule. If calcium sul- 
phate be present in such tartrates or citrates, loss of potassium 
carbonate will ensue, potassium sulphate being formed. In 
examining acid potassium tartrate, which is the salt most likely 
to contain calcium sulphate, direct titration with volumetric solu- 
tion of sodium hydroxide may be employed {see next section). 
Seven or eight percent, of calcium tartrate is commonly present 
in commercial cream of tartar. The U. S. Pharmacopoeia 
requires that the salt should contain not less than 99 percent, of 
pure potassium bitartrate.— i?oc/?e^/e Salt and Sodium Benzoate 
should each be pure within 1 percent. 

Notes. 

Alkalimetry. — The foregoing processes are often spoken of as 
those of alkalimetry (the measurement of alkalies). 

Solution of Litmus may be prepared by boiling in water pow- 
dered litmus, which has been successively extracted with several 
quantities of boiling alcohol and with cold water. The solution 
may be kept in a stoppered bottle, and occasionally exposed to 
the air. 

Weighing. — In the case of substances which are liable to alter 
by exposure to air, it is important that a selected quantity should 
be weighed, rather than that selected weights from the weight-box 
be accurately balanced by material, the former operation occupy- 
ing much the shorter time. The procedure adopted for Solutions 
of Ammonia (p. 615) may also be employed. 



VOLUMETRIC DETERMINATION OF ACIDS. 621 



QUESTIONS AND EXERCISES. 

On what fundamental laws are the operations of quantitative analysis 
based? — What is the general nature of gravimetric quantitative analysis? 
— Explain the principle of volumetric quantitative analysis ? — Define (1) a 
standard and (2) a normal solution. — Describe the apparatus used in vol- 
umetric determinations. — One hundred cubic centimetres of solution of 
sulphuric acid contain 4.8675 grammes of hydrogen sulphate ; calculate 
what weights of potassium bicarbonate and anhydrous sodium carbonate 
that volume will neutralize. Ans., 9.939 grammes and 5.266 grammes. — 
Show what weight of potassium hydroxide is contained in a solution of 
potash 48.02 grammes of which are neutralized by 50 Cc. of normal 
solution of sulphuric acid. Ayis., 5.80 percent. — Calculate the percentage 
of calcium hydroxide in lime water 480 grammes of which are neutral- 
ized by 20 Cc. of the volumetric solution of sulphuric acid. Ans., 0.153. 
— Eight grammes of a sample of Rochellesalt, after ignition, etc., require 
54.3 Cc. of the oflBcial sulphuric acid solution for complete neutraliza- 
tion ; calculate the centesimal proportion of sodium potassium tartrate 
present. Ans., 95.075. 



DETERMINATION OF ACIDS. 

In the previous experiments a known quantity of an acid has 
been used in determining unknown quantities of alkalies. In 
those about to be described a known quantity of an alkali is em- 
ployed in determining unknown quantities of acids. The alkali 
selected may be either a hydroxide or a carbonate, but the former 
is to be preferred; for the carbonic acid set free when a strong 
acid is added to a carbonate, interferes to some extent with the 
indications of alkalinity, acidity, or neutrality, afforded by litmus. 
The alkali most convenient for use is sodium hydroxide, a solu- 
tion of which has probably already been made the subject of ex- 
periment in operations with the normal solution of sulphuric acid. 
It should be kept in a stoppered bottle, and exposed to air as little 
as possible. 



$f 



Volumetric Solution of Sodium Hydroxide. 

(Sodium Hydroxide, NaOH=39.76.) 

This aqueous solution is most conveniently made of such con- 
centration that 1000 Cc. contain the formula weight in grammes 
of the alkali (NaOH=39.76). It will be seen fVom the follow- 
ing equation that 39.76 grammes of sodium hydroxide convert 
48.675 grammes of sulphuric acid into neutral sodium sulphate. 
Therefore one litre of this normal solution, containing 89.76 
grammes of sodium hydroxide, will form a neutral sohitiou of sul- 
phate with one litre of normal sulphuric acid solution, or with a 



622 VOLUMETRIC ANALYSIS. 

chemically equivalent quantity of sulphuric acid solution of any 
other concentration : — 

H^SO, + 2NaOH = Na^SO, + 2H2O 

2)97.35 2)79.52 

48. 675=1000 Cc. of normal solution. 39. 76=1000 Cc. of normal solution. 

If pure sodium hydroxide were at hand, it would only be neces- 
sary to weigh 39.76 grammes, dissolve this in water, and dilute to 
one litre. But the pure hydroxide cannot readily be obtained. 
Therefore weigh about 45 grammes of ordinary sodium hydroxide, 
dissolve in water, and Avheu cool make up the volume of the solu- 
tion to one litre. Then take, say, 14 Cc. , dilute with more water 
in a flask, add a few drops of solution of litmus, and titrate with 
sulphuric acid solution of known concentration. Suppose that the 
volume of normal acid solution required to neutralize the 14 Cc. 
of the soda solution has been 15 Cc, or that an equivalent quan- 
tity of acid solution of another concentration has been used; 
then, how many Cc. of the soda solution are equivalent in 1000 
Cc. of normal acid solution; or, what comes to the same thing, 
how many Cc. of the solution contain 39.76 grammes of sodium 
hydroxide ? It is found that 933 Cc. of the solution contain, 
39.76 grammes of sodium hydroxide. The solution may either 
be diluted, every 933 Cc. to 1000 Cc, so that it mav be normal 
(1000 Cc = 39.76 grammes NaOH), or it maybe used without 
dilution (933 Cc. = 39. 76 grammes NaOH), care being taken to 
introduce the necessary correction. It has already been men- 
tioned that sodium hydroxide nearly always contains carbonate. 
To remove resulting carbonic acid, therefore, the solution should 
be heated toward the close of each titration in all the determina- 
tions in which litmus is the indicator. When methyl orange is 
used no boiling is required, as that indicator is not affected by car- 
bonic acid. The following substances are among those which 
may be determined with normal sodium hydroxide solution. 

Acetic Acid. — Operate upon about 1 gramme of glacial acid, 
about 20 grammes of diluted acid, or about 3 grammes of ordi- 
nary acetic acid. 

HC2H3O, + NaOH = NaC,H302 + H^O 

59. 58 39. 76=1000 Cc. normal solution. 



Acetic Acid, U. S. P. , should contain 36 percent, of hydrogen 
acetate (HC^HgOj). Diluted Acetic Acid, U. S. P., 6 percent. 
Glacial Acetic Acid, U. S. P., 99 percent. 



VOLUMETRIC DETERMINATION OF ACIDS. 623 

Citric Acid. — Operate on about 1 gramme. The reaction is 
represented by the following equation : — 

H3C,H50,,H,0 + 3NaOH = NagCgH^O, + 4H2C 



3|208^5 3 )119.28 

69. 5 39. 76=1000 Cc. normal solution. 

Hydrochloric Acid. — Operate on from 1 to 2 grammes of the 
concentrated acid, or on about 4 grammes of the diluted acid. 

HCl + NaOH = NaCl + Hp 

36. 18 39. 76=1000 Cc. normal solution. 

Hydrochloric Acid, U. S. P., should contain 31.9 percent, of 
real acid (HCl); and Diluted Hydrochloric Acid, U. S. P., 10 
percent. Diluted Hydrobromic Acid, U. S. P., 10 percent. 
(HBr.). 

Lactic Acid, U. S. P.., contains not less than 75 percent, of 
real acid. 

Nitric Acid. — Operate on from 1 to 2 grammes of concentrated, 
or on 4 to 5 grammes of diluted acid. 

HNO3 + NaOH = NaNO, 4- H^O 

62. 57 39. 76=grammes in 1000 Cc. normal solution. 

Nitric Acid, U. S. P., should contain 68 percent; and Diluted 
Nitric Acid., U. S. P., 10 percent, of hydrogen nitrate (HNO3). 

Sulphuric Acid. — Operate upon from 0.5 to 1 gramme of con- 
centrated acid, or from 4 to 5 grammes of either Diluted or Aro- 
matic Sulphuric Acid. 

2NaOH =. Na,SO, + 2H,0 
2 )97.35 2 )79.52 ' 

48. 675 39. 76=grammes in 1000 Cc. normal solution. 

Sulphuric Acid, U. S. P., should contain not less than 92.5 
percent.; Diluted, U. S. P., 10 percent. ; and Aromatic, the equiv- 
alent of 20 percent, of hydrogen sulphate (H.^SOJ. 

Tartaric Acid. — Operate upon about 1 gramme of the acid. The 
following equation represents the reaction : — 

H,C,Hp, + 2NaOH = Na,C,H,0, + 2H,0 

•2 )148.92 2)79.52 

74.46 39.76 = grammes in 1000 Cc. normal solution. 

Notes. — 1. Pure acetates, citrates more especially, tartrates, and 
some other organic salts, have an alkaline action* on litmus, but 



624 ■ VOLUMETRIC ANALYSIS. 

not to an important extent. If the sodium hydroxide solution be 
added to acetic, citric, or tartaric acid, containing litmus, until 
the liquid is fairly blue, the operator will obtain fairly trustworthy 
results ; but in delicate experiments turmeric or phenol-phthalein 
should be used instead of litmus. Phenol-phthalein is produced by 
interaction of phenol and phthalic anhydride. Its solution in aque- 
ous alcohol yields an intense red color with potassium or sodium 
hydroxides, hence may be used as an indicator of the termination 
of volumetric reactions, especially those with organic acids. 
Phenol-phthalein Test Solution, U. S. P., is made by dissolving 
1 gramme of phenol-phthalein in 50 Cc. of alcohol and 100 Cc. 
of water. 

2. The term acldlmetry is applied to such operations as those 
described above for the determination of the quantities of acids in 
solutions. 



QUESTIONS AND EXEECISES. 

Calculate the percentage of real acid present in dilute sulphuric acid 30 
grammes of which are neutralized by 84 Cc. of the official volumetric solu- 
tion of sodium hydroxide. Ans., 13.628. — Show how much real nitric acid 
is contained in a solution 36 grammes of which are neutralized by 94 Cc. 
of normal solution of sodium hydroxide. Ans., 16.34 percent. 



DETERMINATION OF ACID RADICALS PRECIPITATED] 
BY SILVER NITRATE. 

The purity of many salts and the concentrations of their solu- 
tions may be determined by this process ; but officially it is chiefly 
used for the determination of diluted hydrocyanic acid, otherj 
cyanides, and some bromides and iodides. 

Standaed Solution of Silver IS^itrate. 
(Silver Xitrate, AgXOg = 168.69.) 

Dissolve 16.869 grammes of jjure silver nitrate in one litre of 
water. 1000 Cc. of this solution contain J^ of the formula weight in 
grammes of silver nitrate. It is therefore a tenth-normal solution. 

If pure dry crystals of silver nitrate are not at disposal, and 
pure dry crystals of sodium chloride are at hand, a solution may 
be made of approximate strength and then be standardized by 
means of the latter salt. The method may thus be indicated : — 

NaCl + AgNO, = AgCl + NaNO, 
1 0)58.06 10 )168.69 

^ H(\(\ 1 (K ftflQ = grammes in 1000 Cc. 

&.80b lb. 8b J tenth-normal solution. 



DETERMINATION BY SILVER NITRATE. 



625 



Take rather less than 0. 1 gramme of the sodium chloride (NaCl), 
and dissolve it in water. The silver chloride (AgCl) precipitated 
in the reaction is an insoluble salt, and the end of its precipitation 
will serve as a good indication of the completion of the reaction. 
A better indicator, however, is a drop of solution of potassium 
chromate ; the potassium chromate used must be free from chloride. 
The silver nitrate does not act upon the chromate until all the 
chloride is converted into silver chloride, after which a deep red 
precipitate of silver chromate is produced. This indication is 
extremely delicate, and in practice is noticed when the white color 
due to silver chloride changes to yellowish from formation of the 
first traces of silver chromate. Solutions should be cool and not 
very dilute. 

Hydrocyanic Acid. — Three to four grammes oi diluted diOi^HoYixi 
a convenient quantity to operate upon. The HON is first converted 
into KCN or NaCN (by addition of sodium hydroxide). The 
following equations explain the reactions : — 



2HCN + 2NaOH = 2NaCN 



10 )53.68 
5.368 



10) 97.44 
9.744 



2NaCN 4- AgNOg = NaCN,AgCN 



2HP 



NaNO, 



10)97.4£ 
9.744 



10) 168.69 
16.869 



grammes in 1000 Cc. tenth-normal solution. 

It seems that 5. 368 grammes of hydrogen cyanide (HON) are equiv- 
alent to 9.744 grammes of sodium cyanide, and represent 16.869 
grammes of silver nitrate, or 1000 Cc. of tenth-normal solution 
of silver nitrate. 

The sodium cyanide having been obtained, the titration is carried 
on until the salt is converted into the double salt (NaCN,AgCN), 
immediately after which a permanent turbidity occurs, due to 
precipitation of silver cyanide, thus : — 

AgCN,NaCN + AgN03 = 2AgCN + NaNO^ 

The commencement of this turbidity forms a delicate and satis- 
factory proof of the completion of the volumetric reaction. 

There is, however, a difliculty in the conversion of the acid 
into the cyanide (Siebold), to which it is necessary to pay particu- 
lar attention. Solution of litmus is added to the acid diluted 
largely with water, and the sodium hydroxide solution poured in. 
Owing to the strong alkaline reaction of the sodium cyanide formed, 
the mixture becomes blue when only a small projior'tion of the acid 
has been converted. If then the titration be conducted until the 
turbidity appears, only the sodium cyanide will be estimated, leav- 
ing free hydrocyanic acid still unacted upon. Indeed, sodium cyim- 
40 



626 VOLUMETRIC ASALYSIS. 

ide may be estimated in presence of hydrocyanic acid in this way. 
Thustiie following reaction (expressed approximately) might occur. 
NaCN -r- 4HCX - AgXUg = AgCN - XaN03 = 4HCX 



Alkaline Turbid aud acid 

In this case only one-fifth of the cyanogen originally present 
would be precipitated. The mixture would, however, become 
acid. If this acidity be prevented, all difficulty is overcome. 
The following details (Senier) will be found to answer well. To 
the diluted hydrocyanic acid add sodium hydroxide solution until 
a strongly alkaline reaction is shown by the solution of litmus. 
Then add the silver solution drop by drop from the burette, Avhen 
in most cases the mixture will become acid. When it does so, 
add more sodium hydroxide solution, and repeat this process until 
the final reading, when the solution must be alkaline. In this 
way the addition of too much sodium hydroxide at the commence- 
ment, which would use up silver solution and make the reading 
a trifle too high, is avoided. 

Diluted Hydrocyanic Acid, U. S. P., should contain 2 percent, 
of hydrogen cyanide (HCX). 

Fota-ssium Cyanide. — A sample, of which 0.1 gramme, in dilute 
solution, requires 7. 3 Cc. of tenth-normal silver nitrate solution, 
contains 95 percent, of real cyanide. Any sulphide may be removed 
by shaking the solution with lead carbonate. Other ordinary im- 
purities do not interfere. 

The potassium cyanide of commerce very often contains consid- 
erable quantities of sodium cyanide. The cyanide in it is usually 
calculated to potassium cyanide, so that as the atomic weight of 
sodium is much less than that of potassium it is quite possible for 
a sample of '' Potassium Cyanide" to appear as containing more 
than 100 percent, of that salt. 

Ammonurni Bromide. — Take 0.1 to 0.2 gramme and conduct the 
titration in the same manner as for sodium chloride, using potas- 
sium chromate as indicator : — 

XH^Br -^ AgXOs = AgBr - XH^XOg 

1 0)97.29 10)168.69 

n -.on AC Q«Q f = grammes in lOon Cc. of 

9. / 29 lb. ^bii I tenth -normal solntion. 

PotaR.vnm Bromide. -^Operate upon rather less than 0. 1 gramme, 
and conduct the titration in the same manner as with sodium 
chloride, using potassium chromate as indicator : — 

KBr + AgNO, = AgBr 4- KNO3 

10)118^22 10 )166.69 

-I -I Qoo i« CAO f = arrammes in 1000 Cc. of 

II.OZZ ID.ODJ-^ tenth-uormal solution. 



DETERMINATION BY SILVER NITRATE. 



627 



Remembering that 168.69 parts of silver nitrate (AglSTOg = 
168.69) decompose 118.22 of potassium bromide (KBr -= 118.22), 
while on the one hand they decompose as little as 74.04 of potas- 
sium chloride (KCl = 74.04), and on the other hand as much as 
164.76 parts of potassium iodide (KI = 164.76), it will be seen 
that the quantitative operation of the chloride as an impurity may 
neutralize the quantitative operation of the iodide. Hence the 
necessity to test the bromide qualitatively as well as quantitatively, 
and, as regards either impurity singly, of fixing maximum as well 
as minimum limits of the action of the volumetric solution of 
silver nitrate on potassium bromide. One gramme dissolved in 
water, requires for complete precipitation not less than 82 nor 
more than 86.1 cubic centimetres of the volumetric solution of 
silver nitrate. 

Potassium Iodide. — 0.5 Gm. should require not less than 30 Cc. 
and not more than 30.8 Cc. The salt is often 98 or 99 percent, 
pure, containing not more than 0. 5 percent, of chloride, with some 
sulphate and carbonate. 

Sodium Iodide. — 0.5 Gm. should require not less than 33 Cc. 
nor more than 34.6 Cc, equivalent to at least 98 percent, of sodium 
iodide. 

Potassium Iodide may be determined volumetrically by means 
of a twentieth-normal solution of mercuric chloride, the termina- 
tion of the operation being indicated by the commencement of the 
formation of a red precipitate : — 

(1) 3KI + HgCL, = 2KC1 -f 2KHgl3 (soluble). 

(2) 2KHgl3 + HgCl^ -= 2KC1 + SHgl^ (insoluble). 

The author of this process, M. Personne, stated in 1875 that 
neither chlorides, bromides, nor carbonates interfere. Carles dis- 
solves the iodide in alcohol of 17 J percent., as much excess of 
water may decompose the double iodide. 

Ferrous Iodide. — Messrs Naylor and Hooper in 1881 demon- 
strated that Personne' s solution is applicable to ferrous iodide, 
even in the state of syrup : — 

(1) 2Fel2 + HgCl^ = FeCl, + Ye\,llg\ (soluble). 

(2) Fel2,HgI, + HgCl, = FeCl, + 2HgI, (insoluble). 

The use of mercuric chloride for determining the strength of 
syrup of ferrous iodide was first suggested by E. Smith in 1859. 
The process was improved by T. & H. Smith in 1860. 



QUESTIONS AND EXERCISES. 

Explain the volumetric method of determining the strength of aqueous 
sohitions of hydrocyanic acid. — Calcuhite how much silver nitrate Avill 
indicate the presence of 1 part of real hydrocyanic acid. Ans., 3.11 
parts. 



628 



VOLUMETRIC ANALYSIS. 



DETERMINATION OF SUBSTANCES READILY 
OXIDIZED. 

Any substance which quickly unites with a definite weight of 
oxygen, or is susceptible of any equivalent action, may be quanti- 
tatively tested by ascertaining how much of an oxidizing agent 
of known power must be added to a given quantity before com- 
plete oxidation is effected. The oxidizing agents employed for 
this purpose in the Pharmacopoeia are iodine, potassium dichro- 
mate, and potassium permanganate. Iodine acts indirectly, by 
taking hydrogen from water and liberating oxygen ; potassium 
dichromate directly, by the facility Avith which it yields three- 
sevenths of its oxygen — as indicated by the equations and state- 
ments given on pp. 631 and 632 ; potassium permanganate, by 
affording five-eighths of its oxygen in presence of an acid and an 
oxidizable substance (p. 633) : — 



2KMnO. 



4H2SO, = 2KHS0, 



2MnS0, + 3Kfi + 50 



Standard Solutiois^ of Iodine. 
(Iodine, I = 125.9.) 

If pure iodine be not at hand, it may be prepared by mixing 
the commercial article with about a fourth of its weight of potas- 
sium iodide and subliming. Sublimation may be effected by 
gently warming the mixture in a beaker, the mouth of which is 
closed by a funnel ; the iodine vapor condenses on the funnel, 
while fixed impurities are left behind, and any chlorine which the 
iodine may contain is absorbed by the potassium iodide, an equiv- 
alent quantity of iodine being liberated. Small quantities may 
be similarly treated between two watch-glasses, placed edge toi 
edge. Any trace of moisture in the resublimed iodine is removed 
by exposure for a few hours under a glass shade placed over a dish . 
containing concentrated sulphuric acid. 

Place 12.59 grammes of pure iodine and about 18 grammes of 
pure potassium iodide (an aqueous solution of which is the best] 
solvent of iodine ; the salt plays no other part in these operations)] 
in a litre flask, add a liftle water and agitate until the iodine is dis- 
solved ; dilute to 1 litre. 

The following substances may be determined by this tenth-nor- 
mal solution : — 

Sulphurous Acid. — Operate on about 0.5 gramme of the acid, 
and dilute with water. If the sulphurous acid be diluted to a less 
degree than 0.04 or 0.05 percent., there will be some risk of the; 
sulphuric acid subsequently formed being again reduced to sul- ' 
phurous acid, with liberation of iodine. In delicate experiments 
the distilled water used for dilution should previously be freed , 



DETERMINATION BY OXIDIZERS. 



629 



from air by boiling, to prevent the small amount of oxidizing 
action which dissolved air would exert. The solution of iodine is 
then added until a slight permanent brown tint is produced, show- 
ing the presence of free iodine. A better indicator of the termina- 
tion of the reaction is starch nlucilage, which gives a blue color 
with the slightest trace of free iodine. 

The following equation shows the reaction that takes place : — 



I, = 2HI 



H..SO. 



20)81^47 _ 
4.0735 



20)251.8 



12.59 



grammes in 1000 Cc. of 
tenth-normal solution. 



The official sulphurous acid should contain not less than 6 per- 
cent, of sulphurous anhydride (SOg). 

Arsenic. — About 1 gramme of solid arsenous a7ihydride, accu- 
rately weighed, should be dissolved in the usual quantity of water, 
heated to boiling, by aid of 1 gramme of sodium bicarbonate. 
The arsenous anhydride is only partly, if at all, converted into 
arsenite ; but the reaction with iodine occurs more readily in a 
solution which is not acid. When the liquid is quite cold, starch 
mucilage is added, and the iodine solution allowed to flow in until, 
after well stirring, a permanent blue color is produced. — If 24.6 
cubic centimetres of the official solution of Arsenous Acid be used 
about 2 grammes of sodium bicarbonate are required. Water is 
added, and the titration performed as before. The following 
equation exhibits the reaction : — 



As,0, 



+ lOH.O 



41. 



SHI + 4H„AsO, 



80)892.88 
1911 



80)10 07.2 
12.59 



grammes in 1000 Cc. of 
tenth-normal solution. 



In the foregoing operation, if ebullition be continued longer 
than is necessary for the solution of the arsenous anhydride, more 
sodium carbonate may be formed than will be reconverted into 
bicarbonate by the liberated carbonic acid ; loss of iodine will 
then ensue. The results obtained by this method are therefore 
liable to vary slightly. E. J. Woolley showed that borax may be 
used with advantage in place of the sodium bicarbonate. The 
results of latter experiments confirm this conclusion, and show 
that determinations can be carried out not only more accurately, 
but more conveniently and quickly if borax is used, for it is a 
satisfactory solvent for arsenous anhydride and has not the dis- 
advantage of being decomposed during the ebullition. 

Sodmm arsenate may be determined by trenting it with sulphur- 
ous acid, boiling to expel the excess of the acid and then titrating 
with tenth-normal iodine solution as above. 



630 VOLUMETRIC ANALYSIS. 

Xa^HAsO, -r H^SOg = NaAsO^ + NaHSO, + Hp 

Antimony is also raised in valency under the influence of nas- 
cent oxygen, iodine, or an equivalent acid radical. The following 
equation illustrates the reaction with tartarated antimony and 
iodine. The student should make several determinations with, 
say, 20 Cc. of a solution containing 2 grammes of pure tartarated 
antimony in 200 Cc. To the 20 Cc. add about an aqual volume 
of concentrated solution of sodium bicarbonate and 2 Cc. of starch 
mucilage, and then the iodine solution, until, after stirring, the 
blue color is fairly persistent. The whole operation should be con- 
ducted rapidly or a precipitate of antimonious hydroxide will be 
formed, and it is only when in solution that the antimony is 
properly attacked. This process is due to Mohr. 

(KSbOC,H,Og),, H,0 - 21.^ - 3H,0 = 4HI - 2KHC,HPg4- 2HSb03 

40 )659.80 40 )503.6 

la A7~^ 1 9 ^Q ^ = grammes in 1000 Cc. of 

10.^/. J L-.oy I tenth-normal solution. 

Sodium TJiiosuIphate. — About 0.4 gramme is a convenient 
quantity to employ. It is dissolved in water, starch mucilage 
added, and the iodine solution slowly run in, the whole being 
frequently stirred, until a permanent IdIuc color is produced. 

In the previous reactions iodine has acted as an indirect oxidiz- 
ing agent by uniting with the hydrogen and thus liberating the 
oxygen of water. In the present case it unites with an analogue of 
hydrogen, namely sodium, a new salt (sodium tetrathionate) being 
also produced, thus : — 

2(Na,S.p3,5H,0) 4- I, = 2NaI -[- Na^Sp^ -f lOH^O 
2 0)492.92 2 0)251.8 

9J. P,±R 1 9 ^Q ^ = erammes in 1000 Cc. of 

_-±. u-±u L—oxj -^ tenth-normal solution. 

The U. S. P. requires that the salt contain not less than 98 per- 
cent, of sodium thiosulphate. 

Xote. — Sodium thiosulphate may be obtained in a perfectly dry 
condition by treating the powdered salt with alcohol (90 or 95 per- 
cent.), filtering, removing the excess of alcohol by washing with 
ether, and then expelling the ether by a current of dry air. 



QUESTIONS AXD EXERCISES. 

Give equations illustrative of the reactions on which the use of a stand- 
ard volumetric solution of iodine is based. — From what point of view is 
iodine an oxidizing agent ? — What reagent indicates the termination of 
the reaction between reducing substances and moist iodine? — How much 



DETERMINATION BY OXIDIZERS. 



631 



sulpliurous anhydride will cause the absorption of 2.518 parts of iodine in 
the volumetric reaction? Ans., 0.6358. — What quantity of iodine will be 
required, under appropriate conditions, to oxidize 5 parts of arsenous anhy- 
dride ? Ans., 12.805. — Find by calculation the amount of sodium thio- 
sulphate, which will react with 13 parts of iodine in volumetric analysis. 
Ans., 25.446. 



Volumetric Solution of Potassium Bichromate. 

(Potassium Dichromate, K^Crp^ -= 292.28) 

When used as an oxidizing agent in acid solution, potassium 
dichromate yields the whole of its oxygen to the hydrogen of the 
accompanying acid, a corresponding quantity of acid radical being 
set free — four-sevenths of this radical immediately combining 
with the potassium and chromium of the dichromate, three-sevenths 
becoming available for oxidation. Ferrous salts may thus be con- 
verted into ferric with sufficient rapidity and exactitude to admit 
of the determination of an unknown quantity of iron by a known 
quantity of the dichromate. 

K,CrA+8H,SO,+6FeSO,=2KHS04 + Cr.,(S04)3+7H.p+3Fe,(SOj3 

The volumetric solution is made by dissolving 4.8713 grammes 
(eV of the formula weight in grammes) of potassium dichromate 
in water, and diluting to one litre. It is used in determining the 
quantity of ferrous iron present in a preparation. It is known 
that the whole of the ferrous has been converted to ferric salt 
when a small drop of the liquid placed in contact with a drop of a 
fresh and very dilute solution of potassium ferricyanide, on a white 
plate, no longer produces a blue color. 

Ifthe dichromate employed in making this solution is not known 
to be pure and dry, the concentration of the solution may be 
checked by dissolving on accurately weighed piece of pianoforte 
wire (0.4 or 0.5 gramme) in dilute sulphuric acid in a small flask, 
warming, and then adding the solution of dichromate until con- 
version is effected. 

The reactions which take place may be thus represented : — 



6Fe + 


GH^SO, 


= GFeSO, 


60)333 
5.55 




60)905. 1 
le5.085 



+ 6H., 



6FeS0, +K,Cr.A+8H,SO,-=2KHSO,+Cr.,(SO0:,+7IT,O+3Fo,(SO,\ 
60)905.1 60)292.28 



15.085 



4.8713 ^ grammes in 1000 Cc. of tenth-normal solution. 



632 



VOLUMETRIC ANALYSIS. 



It is evident that 5.55 grammes of iron are equivalent in the 
reactions to 4. 8713 grammes of dichromate {i.e., to 1000 Co. of 
the standard solution). Now supposing that 0. 5 gramme of piano- 
forte wire has been employed, and the quantity of solution of 
dichromate of unknown strength used has been 88 Cc. ; how many 
Co. of this solution contain 4.8713 grammes of dichromate, that 
is, how many Cc. will be required to oxidize ferrous salt contain- 
ing 5.55 grammes of iron? By calculation it is found that 978.5 
Cc. contain 4. 8713 grammes of dichromate, and are equivalent to 
1000 Cc. of standard solution. It might be employed without 
being diluted or, better, be diluted to official standard (tenth-nor- 
mal) strength. 

For standardizing the solution of dichromate, instead of iron 
wire, the light-green crystals of the double anwionium ferrous sul- 
2)hate (NHj^SO^FeSO^GHp = 389.44) may be used, for it is a 
very stable salt. 

Special care should be taken in all these determinations of sub- 
stances readily oxidized to avoid atmospheric oxidation. Flasks 
may be loosely corked, or corked closely with a gas exit-tube pass- 
ing just beneath the surface of a little mercury or sodium carbon- 
ate solution, and in all cases the titration should be performed 
, quickly. When standardizing with iron wire, any slight oxidation 
may be remedied by addition of a fragment of zinc, the last por- 
tions of which must be removed or dissolved before the titration 
is commenced. 

The ferrous salt in the following substances may be determined 
by this solution. 

Ferrous sulphafe. — Use 1 to 2 grammes. Dissolve the sulphate 
in water and add excess of sulphuric acid ; the preceding equation 
indicates the reaction. 

Saccharated Ferrous Carbonate. — Dissolve 1 to 2 grammes in 
excess of dilute sulphuric or hydrochloric acid. Sulphuric acid 
is preferable because ferrous sulphate absorbs oxygen much less 
readily than ferrous chloride. The reaction that takes place with 
dichromate is shown in the following equation : — 



6FeC0, 



I4H2SO, 



K,Cr,0, 



60) 690.3 
11.505 

2KHS0. 4- 



Cr,(SO,), 



60)292.28 



4. 



71 q f ==grammes in 1000 Cc. of 
' -"^^ 1 tenth-normal solntion. 



3Fe(S0J, + 13R,0 + GCO^ 



TheU. S. P. requires not less than 15 percent, of ferrous car- 
bonate. Commercial samples yield from 20 to 30, and sometimes 
35 percent., according to the care with which oxidation has been 
prevented. The theoretical percentage obtainable from the in- 
gredients is 45.5, the quantity that would be present if the com- 



DETERMINATION BY OXIDIZERS. 



633 



pounds were anhydrous and unoxidized — conditions never obtained 
in practiee. Phosphoric acid should be used to dissolve the sac- 
charated ferrous carbonate, the reason for this being that dilute 
hydrochloric or sulphuric acid converts ordinary sugar into inverted 
sugar, which is easily attacked by chromic acid. 

Magnetic Iron Oxide. — Use about the same quantity as of arsen- 
ate or phosphate, and proceed in the same manner. The reaction 
may thus be shown — 



60) 1380.12 
23.002 

2KHS0. 



K,Cr,0, = 



60)292.28 



4.8713 



grammes in 1000 Cc. of 
tenth-normal solution. 



Cr,(S0,)3 + 9Fe,(SO,)3 



31HP 



Absolutely pure magnetic oxide of iron contains 31 percent, of 
ferrous oxide. Oxidation occurs, however, during manufacture, 
as in the case of the ferrous salts just described. 

Note. — The use in quantitative analysis of this volumetric solu- 
tion of potassium dichromate admits of great extension. The stu- 
dent should at least employ it in the case of a few iron ores. 



Volumetric Solution of Potassium Permanganate. 
(Potassium Permanganate, KMnO^ = 156.98.) 

Dissolve 3. 3 grammes of potassium permanganate in water and 
dilute to one litre. The solution is then standardized by means 
of a weighed quantity of pianoforte wire or of ammonium ferrous 
sulphate as described under potassium dichromate. 



lOFe + 



lOH^SO, = 



lOFeSO, + lOH, 



10 0)555 
5.56 
lOFeSO, + 2KMnO, 



100)1508.5 



15.085 



9H2SO, = 



100)1 508.5 100 )313.96 



15.085 



3. 1396 = grammes in 1000 Cc. of standard solution. 



2KHS0, + 2MnS0, + 8H,,0 



f 5Fe(SOj3 
cases for which the 



This solution may be^ used in nearly all 
volumetric solution of potassium dichromate has been recom- 
mended. It must not be used in presence of hydrochloric acid, 
as this acid is itself attacked by permanganate with production of 
water and chlorine. 



634 



VOL U METRIC A SA L YSIS, 



Oxalic acid and other oxalates may be determined by means of 
this standard solution of permanganate. About 0. 2 gramme of 
crystallized oxalic acid or about 0. 25 gramme of ammonium oxa- 
late, (NHJ2C'20^,H20, may be dissolved in water, a small quantity 
of dilute sulphuric acid added, the solution warmed to about 60° 
C, and the volumetric solution of permanganate run in from a 
burette until a slight but permanent pink coloration, due to excess 
of permanganate, is produced. 

5(H2C.,0„2H20) + 2KMnO, + 4H2SO, = 



10 0)625.50 
6.255 

2KHS0. 



100)31 3.96 

3. 196 = grammes in 1000 Cc. standard sol. 

lOCO, 



2MnS0, + 



I8H2O 



+ 



It is obvious that pure crystallized oxalic acid may be used as 
a means of standardizing the potassium permanganate solution. 



QUESTIONS AND EXERCISES. 

Write equations explanatory of the oxidizing action of potassium di- 
chromate. — One hundred Cc. of an aqueous solution of potassium dichro- 
mate contain ^ J^ of the formula weight of the salt in grammes ; with what 
weight of metallic iron, dissolved in hydrochloric acid, will this volume 
react? Ans., 0.556 grammes. — If 3 grammes of impure crystallized ferrous 
sulphate dissolved in acidulated water, require 93 Cc. of the standard solu- 
tion of dichromate for complete conversion into ferric salt, what percent- 
age of ferrous sulphate is present? Ans., 85.6. — How much potassium 
dichromate is required for the conversion of 10 parts of crystallized ferrous 
sulphate into ferric salt? Ans.. 1.763.— Show what quantity of pure 
ferrous carbonate is indicated by 1.475 parts of dichromate as applied in 
volumetric analysis. Ans., 3.48. — What quantity of official saccharated 
ferrous carbonate is equivalent to 0.7375 part of dichromate in the volu- 
metric reaction ? Ans., 5.2. 



DETERMINATION OF SUBSTANCES READILY 
REDUCED. 

Any substance w^hich quickly yields a definite quantity of oxy- 
gen may be quantitatively tested by ascertaining how much of a 
reducing agent of known power must be added to a given quantity 
before complete reduction is effected. The chief compounds which 
may be used for this absorption of oxygen (deoxidizers or reducing- 
agents, as they are commonly termed) are sodium thiosulphate, 
sulphurous acid, oxalic acid, arsenous acid. The first-named is 
officially used in the determination of free iodine, and, indirectly, 
of chlorine and chlorinated compounds, chromates and ferric salts. 



DETERMINATION OF OXIDIZERS. 635 

Iodine and chlorine are regarded as oxidizing agents, because 
their great affinity for hydrogen enables them to become powerful 
indirect oxidizers in presence of water. 

Standard Solution of Sodium Thiosulphate. 

(Sodium Thiosulphate crystallized, Na2S,03,5H,0 = 246.46.) 

Dissolve 30 grammes of sodium thiosulphate in a litre or less 
of water. Fill a burette with this solution, and allow it to flow 
into a beaker containing, say, 15 Cc. of the volumetric solution 
of iodine until the brown color of the iodine is just discharged — 
or, starch being added, until the blue starch iodide is decolorized. 
(The latter affords the more delicate indication.) When iodine 
and sodium thiosulphate react, two atoms of iodine remove two 
of sodium from two molecules of the sodium thiosulphate, sodium 
tetrathionate being formed, thus : — 

\ + 2(Na2S203,5H20) = 2NaI +NaAOe+10H2O 



20 )251.8 2 0)492.92 

12. 59 == ^''^n/n^^^^^^^® 24. 646=grammes of thiosulphate in 1000 Cc. 
in 1000 Cc. 

Now suppose the number of Cc. required to completely react 
with the 15 Cc. of standard iodine were 14 Cc, how many Cc. of 
this thiosulphate solution would be equivalent to 1000 Cc. of the 
volumetric solution of iodine? In other words, how many Cc. 
contain 24. 646 grammes of thiosulphate ? 933 Cc. of the solution 
of sodium thiosulphate under examination contain 24.646 
grammes of the salt, and are equivalent to 1000 Cc. of the official 
volumetric solution. The 933 Cc. can be diluted to 1000 Cc. or 
used without dilution. In either case its concentration would, as 
usual, be recorded on the label. The following substances may 
be determined by means of sodium thiosulphate solution of known 
concentration. 

A solution of sodium thiosulphate containing 24.646 grammes 
of sodium thiosulphate per litre is described as a tenth-normal 
solution, as each Cc. is equivalent to 1 Cc. of the tenth-normal 
solution of iodine. 

Solution of Chlorine. — About 10 grammes may be taken. Excess 
of potassium iodide is added — that is, to 10 grammes of solution 
of chlorine, about half a gramme of iodide. A quantity of iodine 
is set free by the chlorine exactly in the proportion to their atomic 
weights. The titration is then conducted as already described. 
The following equations show the reactions : — 

CI, + 2KI = I, + 2KC1 

20)70.36 20)251.8 

3.518 12.59 



I 



636 VOLUMETRIC ANALYSIS. 

1, + 2(Na2S20„5H20) = 2XaI + Na^Sp^ + lOH.O 



2 0)251.8 2 0)492.92 

12. 59 24. 646 = grammes in 1000 Cc. of tenth-normal solution. 

It is evident, then, that 1000 Cc. of tenth-normal solution of 
sodium thiosulphate, or a corresponding quantity of a solution of 
different concentration, is equivalent to 3. 518 grammes of chlorine. 

Iodine. — Solid iodine is dissolved in solution of potassium iodide, 
and titrated as already described. About 0. 2 gramme is a conve- 
nient quantity to employ. 1000 Cc. of tenth-normal thiosulphate 
solution is equivalent, as seen in the equation, to 12.59 of iodine. 
It is assumed in this operation that the iodine has been shown by 
qualitative analysis to be free from chlorine and bromine ; for these 
elements resemble iodine in reacting with sodium thiosulphate, 
hence would reckon as iodine in a volumetric assay. The official 
iodine (lodum, U. S. P.), should contain not less than 99 percent, 
of pure iodine. 

Chlorinated Lime. — Operate on from 0.1 to 0.2 gramme. Dis- 
solve in water, and add excess of potassium iodide and dilute hydro- 
chloric acid. 0. 1 to 0. 2 gramme of chlorinated lime requires 0. 4 
to 0. 8 gramme of potassium iodide. The following equations show 
the reactions: — 



CaOCl^ 


f 


2HC1 = CaCl^ 


+ 


HP 


+ 


CI 


CaOCl, 


4- 


H^SO, = CaSO, 


+ 


H^ 


+ 


CI 



The chlorine thus set free liberates an equivalent amount of 
iodine, and this is titrated as before. {See the equations for the 
solution of chlorine, pp. 635, 636.) This chlorine, liberated from 
chlorinated lime by acids, is its available chlorine for indirect oxi- 
dizing action. It should correspond (U. S. P.) to not less than 
30 percent. 

Solution of Chlorinated Lime. — About 2 grammes is a convenient 
quantity to use. 1 gramme of potassium iodide and excess of acid 
should be added, and the available chlorine determined as in the 
case of the solid. 

Solution of Chlorinated Soda. — About 2 grammes are mixed with 
the usual quantity of water, and 1 gramme of potassium iodide 
and excess of acid added. The available chlorine is determined 
as in the case of chlorinated lime. The reaction by which the 
chlorine is evolved is familiar : — 

NaClNaOCl + 2HC1 = 2NaCl + H2O + Cl^ 

The action of the liberated chlorine on the potassium iodide and 
the iodine on the thiosulphate solution has been described under 
* ' solution of chlorine. ' ' The official (U. S. P. ) requirement is at 
least 2. 4 percent. , by weight, of available chlorine. 



DETERMINATION BY OXIDIZERS. 637 

Sodium thiosulphate may also be used for the determination of 
iron in ferric compounds. This method is based on the fact that 
when ferric chloride is digested with potassium iodide, it is re- 
duced to ferrous chloride. Some of the potassium iodide is decom- 
posed by the chlorine thus released, and an equivalent quantity 
of iodine is liberated. The ferric salt should be dissolved in 
hydrochloric acid, the solution nearly neutralized with sodium 
hydroxide solution, transferred to a well-stoppered flask, and ex- 
cess of a concentrated solution of potassium iodide added. The 
flask should then be closely stoppered and heated to 50° or 60° C. 
on a water-bath for about 20 minutes ; iodine is liberated, and 
dissolves in the excess of potassium iodide. After cooling the 
solution and adding mucilage of starch, the thiosulphate solution 
is run in until the blue color disappears. The following equations 
show the reactions : — 

• 2FeCl3 + 2KI = 2FeCl2 + 2KC1 + I^ 

20) 322.08 
16.104 

I^ + 2(Na,S203,5Hp) = 2NaI + Na^S^O^ + lOHp 
20)494.92 



24. 746=grammes in 1000 Cc. of tenth-normal solution. 

Thus it is evident that 1000 Cc. of tenth-normal solution of 
sodium thiosulphate are equivalent to 16.104 grammes of ferric 
chloride. The following official compounds may be examined by 
this method : — Ferri Chloridum, Ferri Citras, Ferri et Ammonii 
Citras, Ferri et Ammonii Sulphas, Ferri et Ammonii Tartras, 
Ferri et Potassii Tartras, Ferri et Quininse Citras, Ferri et Quin- 
inse Citras Solubilis, Ferri et Strychninse Citras, Ferri Phosphas 
Solubilis, Ferri Pyrophosphas Solubili;^, Ferrum Reductum, 
Liquor Ferri Chloridi, Liquor Ferri Subsulphatis, Liquor Ferri 
Tersulphatis, and Tinctura Ferri Chloridi. 



QUESTIONS AND EXERCISES. 

For what purpose is the volumetric solution of sodium thiosulphate 
used? — On what reaction is based the quantitative employment of sodium 
thiosulphate ? — How much sodium thiosulphate is required to show the 
presence of 10 parts of iodine? Ans., 19.574. — Calculate the quantity of 
chlorine 4.96 parts of sodium thiosulphate are equivalent to in volumetric 
analysis. Ans., 0.708. — Describe the operations involved in the determi- 
nation of the strength of bleaching-powders. — Wbat indicator is used to 
show the termination of the reaction between iodine and sodium thio- 
sulphate ? 



638 GRAVIMETRIC ANALYSIS. 

QUESTIONS, WITH ANSWEES FOE YEEIFICATION. 

Calculate how much potassium bicarbonate is contaiued in an eight- 
ounce bottle of medicine, seven fluid drachms of which are neutralized 
by 2.72 grains of pure sulphuric acid. Ans., 36.3 grains. — A sample of 
soda-ash is said to contain 78 percent, of pure anhydrous sodium carbon- 
ate : if the statement be true, how much of the oiiicial volumetric solu- 
tion of sulphuric acid will neutralize 5 grammes of the specimen? Ans., 
74 O. — 2.69 grammes of commercial sulphuric acid are neutralized by 
43.5 Cc. of the official volumetric solution of sodium hydroxide ; how 
much acid of 96.8 percent, is present ? Ans., The 2.69 contain 2.05. — Four 
Cc. of a litre and a half of concentrated hydrocyanic acid are equivalent 
to 89 Cc. of the official volumetric solution of silver nitrate ; to what 
volume must the bulk of the acid be diluted for the production of acid 
of pharmacopoeial strength? Ans., 8.894 litres. — How much pure metal 
is present in a sample of iron 1 gramme of which, dissolved in dilute sul- 
phuric acid, is exactly attacked by 95.7 Cc. of a volumetric solution of 
potassium dichromate which is 0.6 percent, stronger than the official 
solution ? 



GRAVIMETKIC ANALYSIS. 

{For preliminary remarks on the general principles of gravimetric 
analysis and the relation of gravimetric and volumetric analysis to 
each other, see pages 609 and 610. ) 

DETERMINATION OF METALLIC RADICALS. 
POTASSIUM. 

Outline of the Process. — This element is usually determined in 
the form of potassium chloroplatinate. Qualitative analysis hav- 
ing proved the presence of potassium and other radicals in a sub- 
stance, a small quantity of the material is accurataly weighed, 
dissolved, and the other metallic radicals removed by appropriate 
means; the precipitates are well w^ashed, in order that no trace of 
the potassium salt be lost, the resulting liquid concentrated over 
a water-bath (to avoid loss that Avould occur mechanically during 
ebullition), hydrochloric acid added if necessary, solution of 
chloroplatinic acid poured in, and evaporation continued to dry- 
ness : excess of the precipitant is then dissolved out by adding, to 
the dried residue, alcohol (90 percent.) mixed ^vith half its bulk 
of ether (a mixture in which the chloroplatinate is insoluble), the 
whole carefully poured on to a tared and dried filter, washed with 
the mixture of alcohol and ether till every trace of chloroplatinic 
acid is removed, and dried and weighed; from the Aveight of 
potassium chloroplatinate the proportion of potassium, or equiva- 
lent in quantity of a salt of potassium, is ascertained by calculation. 

Note. — From this short description it will be seen, first, that 
the chemistry of quantitative analysis is the same as that of quali- 



DETERMINATION OF POTASSIUM. 639 

tative; and secondly, that the principle of gravimetric is the same 
as that of volumetric quantitative analysis: — the combining pro- 
portions of substances being known, unknown quantities of ele- 
ments may be ascertained by calculation from known quantities 
of their compounds. 

Apparatus. — In addition to the very delicate balance, accu- 
rate weights and the common utensils, a few special instruments 
are used in quantitative manipulation ; some of these may be 
prepared before proceeding with the determination of potas- 
sium. 

Filter-jMper may be of the kind known as " Swedish," the 
texture of which is of the requisite degree of closeness, and 
its ash small in amount. A large number of circular pieces 
of one size, six to eight ceiitimetres in diameter, should be cut 
ready for use. In delicate experiments, where a precipitate 
on a filter has to be ignited and the paper subsequently burnt, 
the weight of the ash of the filter must be deducted from the 
weight of the residue. The ash is determined by burning 
ten or twenty of the cut filters. These are folded into small 
compass, a piece of platinum wire twisted a few times round 
the packet so as to form a , cage, the whole held by the free 
end of the wire over a weighed porcelain crucible placed on 
the centre of a sheet of glazed paper, and the bundle ignited 
by a spirit-lamp or Bunsen flame. The flame is allowed to 
impinge against the charred mass until it falls into the crucible 
below, any stray fragments on the sheet being carefully brushed 
into the crucible, the latter placed over a flame until carbon has 
all been burnt off, and nothing but ash remains; the whole 
cooled, weighed, and the weight of the crucible deducted. 
The weight of the residue divided by the number of pieces 
used gives the average weight of ash in each filter. 

The necessity for carrying out the operations described in 
the preceding paragraph has been almost entirely obviated by 
the introduction of the so-called ashless filters — circular filter 
papers of various sizes, from which the mineral matter which 
gives rise to the ash has been removed, practically completely, 
by extraction with hydrochloric and hydrofluoric acids. 

For the complete retention of certain exceeding finely di- 
vided precipitates, such as barium sulphate, calcium oxalate, 
cuprous thiocyanate, etc., filter papers possessing the closest 
texture must be employed. 

A pair of iveighing tubes (Fig. 72), for holding dried filters, 



640 



GRAVIMETRIC ANALYSIS. 



may bs made from two test-tubes, one fitting closely vvithiu 
the other. About five centimetres of the closed end of the 
outer and seven of the inner are cut off by leading a crack 
round the tube with a pencil of incandescent charcoal, and the 
sharp edges fused in the blow-pipe flame. A filter, after dry- 



FiG. 72. 



Fig. 73. 





A pair of weighing-tubes. Clamped watch-glasses for weighing- 



Fig. 74. 



ing, is quickly folded and placed in the narrower tube, the 
mouth of which is then closed by the wider tube. This pre- 
vents reabsorption of moisture from the air. A pair of ivatch- 
glasses, having accurately ground edges and clamped as shown 
in Fig. 73, forms a convenient arrangement for weighing 
filters, etc. Small iveighing bottles, light stoppered bottles 
having wide mouths, are also useful. 

The wash-bottle (Fig. 74), holding the alcohol and ether, is 
a common flask, through the cork of which a short straight 
tube passes. The outer end of the tube should be sufficiently 
narrowed to enable it to deliver a very fine 
stream of the liquid. The flask being inverted, 
the warmth of the hand expands the air and 
vapor to a sufficient extent to force out the 
liquid. 

The ordinary wash-bottle for quantitative opera- 
tions should be formed of a flask in which 
water may be boiled, fitted up as usual (see p. 
116). 

A water-oven is the best form of drying-apparatus. It is a 
small square copper vessel, jacketed on five sides and having a 
door on the sixth; water is poured into the space between the 
inner and outer casing, and the whole placed over a gas-lamp or 
other source of heat, moist air and steam escaping by appropriate 
apertures. Holes in the top an inch or two in diameter, covered 
when not in use, serve for the reception of small dishes contain- 
ing liquids to be evaporated. Drying at higher temperatures than 
the boiling-point of water may be practised by using oil or paraf- 
fin instead of water, inserting a thermometer in the oil; or by 
the use of an air-bath^ which is simply a metal box provided with 
a door and heated by means of a Bunsen flame. 

A desiccator is a glass vessel in which a substance to be dried, 




DETERMINATION OF POTASSIUM. 



641 



or to be cooled in a dry atmosphere, is enclosed along with a 
powerful dehydrating agent such as concentrated sulphuric acid, 
potassium hydroxide, or fused calcium chloride (Figs. 75 and 76). 

Pure distilled water must be used in all quantitative determina- 
tions. 

Note. — In practising the operations of quantitative analysis, 
experiments should at first be conducted on definite salts of known 
composition, for the accuracy of results may then be tested by 
calculation. 



Fig. 75. 



Fig. 76. 




Desiccator. 



Desiccator. 



Determination of Potassium in the form of Potassium Chloro- 
platinate, — Select two or three crystals of pure potassium 
nitrate, powder them in a clean mortar, dry the powder by 
gently heating in a porcelain crucible over a flame for a few 
seconds, place about a couple of decigrammes (0.2 grm.) of 
the powder in a counterpoised watch-glass, acurately weigh 
the selected quantity, transfer to a small dish, letting water 
from a wash-bottle flow over the w^atch-glass and run into the 
dish, warm the dish until the nitrate is dissolved, acidulate 
with hydrochloric acid, add excess of aqueous solution of 
chloroplatinic acid (a quantity of solution containing about 
0.5 grm. of HgPtClg), evaporate to dryness on a water-bath. 
While evaporation is going on, place a filter and the weighing- 
tubes in the water-oven, exposing them to a temperature of 
100°C. for about half an hour ; fold the filter and insert it in 
the tubes, place them in a desiccator to cool, and when cold 
accurately note their weight. Arrange the weighed filter in 
a funnel over a beaker. Transfer the dried and cooled 
chloroplatinate from the dish to the filter by moistening the 
the residue with the mixture of alcohol and ether and, when 
the salt is loosened, pouring the contents of the dish into the 
41 



642 GRAVIMETRIC ANALYSIS. 

paper cone. Any salt still adhering may be freed by the 
finger, which, together with the dish, should be washed in the 
stream of alcohol and ether, the rinsings at once flowing 
into the filter. The filtrate should have a yellowish-brown 
color, due to the excess of chloroplatinic acid. If it is color- 
less, an insufiicient amount of the precipitant has been added, 
and the whole operation must be repeated. After washing 
with the mixture of alcohol and ether until the liquid is no 
longer colored by chloroplatinic acid, the precipitate and filter 
are dried in the water-oven, folded and placed in the weighing- 
tubes, the tubes placed open in the drying-oven for a short 
time, removed, closed, allowed to cool and then weighed. 
The drying and weighing when cold should be repeated until 
the whole ceases to alter, the final weight being noted. 
Analytical memoranda may have the following form : — 

Watch-glass and substance 

Watch-glass 



Substance 



Weighing-tubes, filter, and salt 
Weighing-tubes and filter . . . 



K^PtCl, 



The calculation are simple : — 

. f K^PtCL ] . . 1 , , f 2KNO3 1 

^' I =482.1 I '' eq^i^-al^^t to I _ 200. 86 | ' 

r the weight of ] 
so \ chloroplatinate I is equivalent to x. 

[ obtained J 

X will be the weight of pure potassium nitrate in the quantity 
of substance operated on. x should in the present instance be 
identical with the weight of substance taken, because, for 
educational purposes, the pure nitrate is under examination. 
Only after analyses of pure substances have yielded the 
operator results practically identical with those obtained by 
calculation, can analyses of substances of unknown degree of 
purity be undertaken with confidence, A table of atomic 
weights, from which to find molecular weights, is given in the 
Appendix. 

Platinum Residues should be preserved, and the metal recovered 
from time to time {see p. 201). 



DETERMINATION OF SODIUM. G43 

Hot alcohol sometimes reduces chloroplatinic acid, the metal 
being thrown out of solution in a finely divided form, known as 
platinum black ; only aqueous solutions, therefore, of this reagent 
should be used where heat is employed. Hence, also, in washing 
out excess of chloroplatinic acid with the mixture of alcohol and 
ether the application of heat should be avoided. 



Proportional Weights of Equivalent Quantities of Potassium and 
some of its Compounds. 

Metal K^ 77.72 

Oxide K^O 93.6 

Hydroxide (Caustic Potash) 2K0H 111.48 

Carbonate (anhydrous) . . K^COg 137.27 

Bicarbonate 2KHCO3 • • • • • 198.82 

Nitrate 2KNO3 200.86 

Chloroplatinate .... . K^PtCJg 482.1 



SODIUM. 

Sodium is usually determined as sulphate. Accurately 
weigh a porcelain crucible and lid, place within it about 0.3 
of pure powdered rock-salt, and again weigh, making a mem- 
orandum of the weights in a note-book. Add rather more 
concentrated sulphuric acid than may be considered sufficient 
to convert the chloride into acid sodium sulphate. Heat the 
crucible gradually, the flame being first directed against the 
side of the crucible to avoid violent ebullition, until fumes of 
acid are no longer evolved, toward the end of the operation 
dropping in one or two fragments of ammonium carbonate to 
facilitate complete expulsion of all excess of acid. When 
cold, weigh the crucible and contents. The weight of the 
crucible having been deducted, the amount of sulphate 
obtained should be the exact equivalent of the quantity of 
sodium chloride taken. 



2NaCl + H^SO, = Na^SO^ + 2HC1 
116.12 141.11 



644 GRAVIMETRIC ANALYSIS. 

Proportional Weights of Equivalent Quantities of Sodium and 
some Sodium Compounds. 

Metal Na^ . • 45.76 

Oxide Nap 61.64 

Hydroxide (Caustic Soda) 2NaOH 79.52 

Carbonate (anhydrous) . Na^COg 105.31 

Carbonate (crystals) . . Na2CO3,10H2O . . . 284.11 

Bicarbonate 2NaHC03 166.86 

Chloride 2NaCl 116.12 

Sulphate (anhydrous) . . Na2S04 141.11 

Sulphate (crystal) . . . . Na^SO^lOHp . • . .319.91 

AMMONIUM. 

Salts of ammonium are, for purposes of quantitative anal- 
ysis, generally converted into the chloroplatiuate (NH^)2PtClg, 
the details of manipulation being the same as those observed 
in the case of potassium (p. 641). About 0.15 gramme of 
pure, white, dry, ammonium chloride may be taken for experi- 
ment. 

Composition of the Chloroplatiuate. 







In formula wt. 


In 100 parts 


Pt . . 


. 193.3 


. . 193.30 . . 


. 43.908 


CI, . . 


. 35.18 X 6 . 


. . 211.08 . . 


. 47.947 


N. . . 


. 13.93 X 2 . 


. . 27.86 . . 


. 6.328 


H3. . 


1.0 X 8 . 


. . 8.00 . . 


. 1.817 




440.24 


100.000 



The proportion of nitrogen, or ammonium, in the chloro- 
platiuate may also be ascertained from the weight of plati- 
num left on ignition; indeed, this operation m\ist be performed 
if methyl-ammonium or any other substituted ammonium be 
present. The heat must be applied slowly, or platinum will 
be mechanically carried off with the gaseous products of 
decomposition. 

Proportional Weights of Equivalent Quantities. 

Ammonia 2NH3 33.86 

Ammonium (NHJ2 35.86 

Ammonium chloride . . . 2NHP1 106.22 

Chloroplatinate (NH^),PtCl, .... 440.24 

'Ammonium carbonate" . (N,Hj;C,05)^3X2 . 104.006 
Ammonium sulphate . . . (NHJ2S0^ 131.21 



BETERMINATTON OF BARIUM. 645 



BARIUM. 

Barium is determined in the form of anhydrous barium 
sulphate (BaSOj. 

Process. — Dissolve 0.3 or 0.4 of pure crystallized and dried 
barium chloride or nitrate in about 100-150 Cc. of water in a 
beaker, heating to incipient ebullition, and slightly acidulating 
with hydrochloric or nitric acid. Heat some dilute sulphuric acid 
(prepared some days previously, so that any lead sulphate may 
have deposited) and add the hot acid to the barium solution 
in successive small quantities so long as a precipitate forms, 
keep the mixture hot for sometime, set aside for half an 
hour, pass the supernatant liquid through a filter, gently 
boil the residue twice or thrice with acidulated water ; finally 
collect the precipitate on the filter, removing adherent parti- 
cles from the beak by the finger, and cleansing by a stream of 
hot water from the wash-bottle. The precipitate must be 
washed with hot water until the filtrate no longer turns litmus- 
paper red or gives any cloudiness when tested with barium 
chloride. The filter with the barium sulphate, having been 
thoroughly drained, is dried in a warm place, usually by sup- 
porting the funnel in an inverted bottomless beaker over a 
sand-bath or hot plate. 

The barium sulphate is now removed from the filter, heated 
to drive oflT every trace of moisture, and weighed. This is 
accomplished by placing a weighed porcelain crucible on a 
sheet of glazed paper, holding the filter over it, and carefully 
transferring the precipitate. The sides of the filter are then 
gently rubbed together and the detached powder dropped into 
the crucible, the paper folded, encased in two or three coils of 
one end of a platinum wire, and burnt over the crucible, the 
ash and any particles on the sheet of paper dropped into the 
barium sulphate, the open crucible exposed over a flame until 
its contents are quite white, covered, cooled, and weighed. 

Note. — If the filter has not been freed by thorough washing 
from all traces of acid the paper will be brittle when dry, 
falling to pieces on being folded. 



Barium chloride . . . 


Formulre 
. . BaCl.„2H„0 . 


Formula 

Wfiirhts. 

. . 242.52 


Barium nitrate . . . 
Barium sulphate . . 


Ba(NO,)/ . . 
. . BaSO/.". . . 


. . 259.54 
. . 281.75 



646 GRAVIMETRIC ANALYSIS. 

Composition of Barium Sulphate. 



Ba . . 

S . . 



. . 136.40 
. . 31.83 
. . 15.88X 4 . 


In formula weight. 
. . 136.40 . . 
. . 31.83 . . 
.. 63.52 . . 


In 100 parts. 
. . 58.86 

. . 13.73 
. . . 27.41 


\J^ . . 








231.75 


100.00 



In the first four or five educational experiments it is not 
essential to take filter-ash into account. Mistakes of manipu- 
lation due to inexperience may cause far greater errors. 

CALCIUM. 

Calcium is usually precipitated as oxalate, the precipitate 
ignited, and the resulting carbonate weighed. 

Process. — Dissolve 0.3 or 0.4 of dried colorless crystals of 
calc-spar in about a third of a litre of water acidulated with 
hydrochloric acid, heat the solution to near the boiling point, 
add excess of boiling solution of ammonium oxalate, then 
ammonia until, after stirring, the liquid smells strongly of 
ammonia ; set aside in a warm place for twelve hours. Care- 
fully pour off the supernatant liquid, passing it through a 
filter ; add hot water to the precipitate, set aside for half an 
hour, again decant, and, after once more washing, transfer the 
precipitate to the filter, allowing all contained fluid to pass 
through before a fresh portion is added. Wash the precipi- 
tate with hot water, avoiding a rapid stream, or the precipi- 
tate may be driven through the pores of the paper. Dry, 
transfer to a weighed crucible, and incinerate, as described for 
barium sulphate, and slowly heat the precipitate until the 
bottom of the crucible is just visibly red when seen in the 
dark. As soon as the residue is white or only faintly gray, 
remove the flame, cool, and weigh. 

The resulting calcium carbonate should have the same 
weight as the calc-spar from which it was obtained. If loss 
has occurred, carbonic anhydride has probably escaped. In 
that case moisten the residue with water, and after a few 
minutes test the liquid with red litmus or turmeric paper ; if 
an alkaline reaction is noticed, it is due to the presence of 
caustic lime. Add a small lump of ammonium carbonate, 
evaporate to dryness on a water-bath, and again ignite, this 



DETERMINATION OF MAGNESIUM. 647 

time being careful not to go beyond the prescribed tempera- 
ture. The treatment may, if necessary, be repeated. 

Proportional Weights of Equivalent Quantities of Calcium and 
some of its Compounds. 

Metal Ca 89.8 

Oxide (quicklime) CaO . 55.68 

Hydroxide (slaked lime) . . . Ca(OH), 73.56 

Carbonate CaCOg 99.35 

Sulphate (anhydrous) CaSO^ 135.15 

Sulphate (crystalline or precipi- 
tated) CaSO,2H20 . . . 170.91 

Chloride CaCl, 110.16 

Phosphate (of bones) .... . Ca3(PO,)2^3 . . .102.66 

MAGNESIUM. 

Process 1. — The magnesium carbonate of pharmacy may be 
examined by heating a weighed quantity to redness in a 
porcelain crucible. If it has the composition indicated by the 
formula given in the Pharmacopoeia, 4MgC03, Mg(dH)^, 
SH^O, it will yield 40 percent, of magnesia (MgO). 

Process 2. — The general form inivhich magnesium is pre- 
cipitated is an ammonium magnesium phosphate (NH^MgPO^, 
6H2O); this by heat is converted into magnesium pyrophos- 
phate (MggPgO^). Accurately wxigh a small quantity (0.4 to 
0.5 gramme) of pure dry magnesium sulphate, dissolve it in 
two to three hundred cubic centimetres of cold water in a 
beaker, add ammonium chloride, ammonia, and sodium or am- 
monium phosphate, agitate with a glass rod (without touching 
the sides of the vessel, or crystals will firmly adhere to the 
rubbed portions), and set aside for twelve hours. Collect the 
precipitate on a filter, wash with water containing a tenth of 
its volume of the strongest solution of ammonia, until the filtrate 
no longer gives a precipitate with a solution of silver nitrate 
acidulated with nitric acid. Dry, transfer to a porcelain 
crucible, burn the filter in the usual way, heat slowly to 
redness, cool, and weigh. 

Proportional Weights of Equivalent Qua)dities of some 
Magnesium Compounds. 

Pyrophosphate . . . Mg^P^O^ 221.06 

Sulphate 2(MgSO,,7H.,0) 489.38 

Oxide 2(MoO) 80. 1 2 

Official carbonate . . 4MgC03,Mg(OH)2,5H,0 -^2 . . . 241.13 



648 



GRAVIMETRIC ANALYSIS. 



ZINC. 

Zinc is usually determined as oxide (ZuO), occasionally as 
sulphide (ZnS). 

Process. — Dissolve a weighed quantity (0.5 to 0.6 gramme) 
of zinc sulphate in about half a litre of water in a beaker, 
heat to near the boiling-point, add solution of sodium carbon- 
ate in slight excess, boil, set aside for a short time ; pass the 
supernatant liquid through a filter, gently boil the precipitate 
with more water, again decant ; repeat these operations two or 
three times ; collect the precipitate on the filter, wash, dry, 
transfer to a crucible, incinerate, ignite, cool, and weigh. 
285.41 (=the formula weight) of sulphate should yield 
80.78 (=the formula weight) of oxide. 



MANGANESE. 

To ascertain its value for evolving chlorine from hydro- 
chloric acid, a weighed quantity of finely powdered black 

Fig. 77. 




manganese oxide is heated in a small flask with pure hydro- 
chloric acid (contained in an inner tube as for "oxalates" 
and "carbonates," p. 665), and the resulting chlorine conveyed 
into a U tube containing solution of potassium iodide. {See 
Fig. 77.) The amount of iodine thus liberated is determined 
by means of the volumetric solution of sodium thiosulphate. 
125.9 parts of iodine indicate 35.18 of chlorine. 

Black manganese oxide may also be estimated by the reac- 
tion and apparatus described under "Oxalates," p. 666. 



DETERMINATION OF ALUMINIUM. G49 

ALUMINIUM. 

Aluminium is always precipitated as hydroxide, A1(0H)3, 
aud weighed as oxide (AI2O3). 

Process. — Dissolve about 2 grammes of pure dry ammo- 
nium-alum in half a litre of water, heat the solution, add am- 
monium chloride and a slight excess of ammonia, boil gently 
until the odor of ammonia has nearly disappeared, set aside for 
the hydroxide to deposit, pass the supernatant liquid through 
a filter, wash the precipitate three or four times by decanta- 
tion, transfer to the filter, finish the washing, dry, burn the 
filter, ignite in a covered crucible, cool, and weigh. 

A1K(S0J2+12H20 471.02 

A1NH,(S0,)2+12H20 450.09 

Al^Og 101.44 

Percent, of AI2O3 yielded by ammonium-alum . 11.27 



QUESTIONS AND EXERCISES. 

Give details of the manipulations observed in gravimetrically deter- 
mining potassium or ammonium. — Wliat quantity of sodium chloride is 
contained in a sample of rock-salt 0.351 gramme of v^^hich yields 0.426 of 
sodium sulphate? Ans., 99.83 percent. — To what weight of ammonium- 
alum is 0.888 gramme of ammonium chloroplatinate equivalent? Ans., 
1.817 gramme. — Find the weight of barium sulphate obtainable from 
0.522 of barium nitrate? Ans.. 0.466 — Describe the usual method by 
w^hich calcium is determined. — By what quantitative process may the 
official magnetism salts be analyzed? — Calculate the proportion of pure 
zinc sulphate in a sample of crystals 0.574 gramme of which yield 
0.161 gramme of oxide; Ans., 99,4 percent.— Ascertain the weight of 
alumina (AI2O3) which should be obtained from 1.812 gramme of am- 
monium-alum. 



IRON. 



Iron and its salts are gravimetrically determined in the 
form of ferric oxide (Fe.^Og). 

Compounds containing organic acid radicals are simply in- 
cinerated, and the resulting oxide weighed. Thus 1 gramme 
of the official iron and ammonium citrate (Ferri et Ammonli 
Citras, U. S. P.), incinerated, with exposure to air, leaves 0.81 
or 0.32 of ferric oxide. A small quantity of tlie salt is 
weighed in a tared covered porcelain crucible and the flame 
ciutiously a])plied until va})ors are no longer evolved. The 



650 GRAVIMETRIC ANALYSIS. 

lid is then removed, the crucible slightly incliued and ex- 
posed to a red heat until all carbonaceous matter has disap- 
peared. After cooling, the residual ferric oxide is weighed. 
The iron and potassium tartrate (^Ferri et Potassii Tartras, 
U. S. P.), is treated in the same manner, except that the ash 
must be washed in order to remove potassium carbonate pro- 
duced during incineration, and again heated before weighing ; 
5 grammes should yield about 1.5 grammes of ferric oxide. 

From other compounds of iron, soluble in water or acid, the 
iron is precipitated in the form of hydroxide, Fe(0H)3 by 
solution of ammonia, and converted into oxide (Fe203), by 
ignition. Dissolve a piece (0.2 gramme) of the purest iron 
obtainable (piano-wire), accurately weighed, in dilute hydro- 
chloric acid ; add a few drops of nitric acid, and gently boil ; 
add excess of ammonia, stir, set aside until the ferric hydroxide 
has deposited, pass the supernatant liquid through a filter, 
treat the precipitate three or four times with boiling water ; 
transfer to the filter, wash until the filtrate yields no trace of 
chloride (for ammonium chloride will decompose ignited ferric 
oxide, with volatilization of ferric chloride), dry, ignite, and 
weigh. Iron in the ofiicial solutions (Liquor Ferri et Am- 
monii Acetatis, Liquor Ferri Chloridi, Liquor Ferri Subsul- 
phatis, and Liquor Ferri Tersulphatis) may be determined by 
this general gravimetric process. 

The proportion of metallic iron in a mixture of iron and iron 
oxides may be determined by digestion in a concentrated solu- 
tion of iodine and potassium iodide, which attacks the metal 
only. The reduced iron of pharmacy (Ferrum Reductum, 
U. S. P.), should contain not less than 90 percent, of free 
metal. 

Projjortional Weights of Equivalent Quantities of Iron 
and some of its Compounds. 

Metal Fe, 111.0 

Ferric oxide Fe'^O, 158.64 

Ferric hydroxide . . . 2Fe(0H), 212.28 

Ferric chloride .... 2FeCl, 322.08 

Ferric sulphate . . . . Fe^CSOJg 397.05 

Ferrous sulphate . . . 2(FeSO„7H,0) .... 552.02 

ARSENIC. 

Arsenous anhydride (As^O,.) and arsenous compounds are 
usually determined volumetrically (see p. 629). Arsenic can 



DETERMINATION OF ARSENIC. 651 

be wholly converted into hydrogen arsenide and determined 
quantitatively by absorbing the hydrogen arsenide in silver 
nitrate solution (p. 204). Toward the end of the operation, 
a solution of stannous chloride in hydrochloric acid is added 
to the contents of the vessel in which the gas is being evolved. 
This causes the precipitation of any arsenic still remaining in 
the solution, in a very finely divided state, in which it is read- 
ily attacked by the nascent hydrogen and converted into 
hydrogen arsenic (Schmidt). 

Process 1. — With certain precautions arsenic may be pre- 
cipitated and weighed as sulphide (As^Sg). The pure while 
arsenic in lump (about 0.2) is dissolved in a flask in small 
quantity of water containing sodium or potassium bicarbonate, 
the liquid being heated. A slight excess of hydrochloric 
acid is then added, and hydrogen sulphide gas passed through 
the solution so long as a precipitate falls, the mouth of the 
flask being stopped by a plug of cotton-wool (to prevent undue 
access of air and consequent decomposition of the gas, resulting 
in precipitation of sulphur). The mixture is warmed in the 
flask and carbonic anhydride passed through it until the odor 
of hydrogen sulphide has nearly disappeared; the precipitate 
is collected on a tared filter, washed as quickly as possible 
with hot water containing a little hydrogen sulphide, dried in |; 

a water-oven, and weighed. 196.64 parts of white arsenic j!. 

should yield 244.46 of arsenous sulphide. ||[| i 

Process- 2. — The arsenic must he preseyitin the highest state If ' 

of oxidation. If the operator is not certain that this is the j 

case, the solution must be warmed with a little hydrochloric 
acid and a few crystals of potassium chlorate added until a 
distinct chlorous odor is evolved — which is then allowed to 
escape by continued application of heat. To the solution thus 
obtained ammonia, which must produce no turbidity, is added 
in excess, and then magnesia mixture {see under *' phos- 
phates," p. 667). The solution is set aside for twenty-four 
or forty-eight hours. The precipitate is collected on a filter 
and washed with as little ammonia water (1 to 3) as posssible 
until the filtrate no longer gives a reaction for chlorides. The 
precipitate is then dried on the filter, the filter-})aper burned 
apart from the precipitate, and the whole gently ignited in a 
porcelain crucible, and weighed. This residue is magnesium 
pyro-arsenate, and has the formula ]\[g,As.,0^. 

Note. — For the determination of minute quantities of arseni(\ 
ill such liquids as beer, and in brewing materials and fuc 1, 



652 GRA VIMETRIC ANALYSIS, 

Thorpe's adaptation ^ of Bloxam's electrolytic method may be 
employed. 

ANTIMONY. 

The metal is precipitated in the form of sulphide (Sb2S3), 
with the precautions observed in determining arsenic — a small 
quantity of tartaric acid, as well as hydrochloric, being added 
to prevent the precipitation of an oxysalt. If the hydrogen 
sulphide be passed through a hot solution, the particles of pre- 
cipitate aggregate better and may be more quickly filtered 
and washed. The experiment may be performed with about 
half a gramme of pure antimony and potassium tartrate ; the 
salt should yield nearly half its weight of sulphide. Accord- 
ing to Fresenius, the sulphide dried at 100° C. still contains 2 
percent, of water, and must be heated in a current of carbonic 
anhydride, until it turns from an orange to a black color, 
before all moisture is expelled. The purity of antimony 
and potassium tartrate, U. S. P., may be determined by the 
above process. 

For the volumetric determination of antimony in anti- 
monious salts, see p. 630. 



COPPER. 

Copper may be determined as metal or as cupric oxide 
(CuO). Sometimes it is precipitated and weighed as cuprous 
thiocyanate or precipitated as cupric sulphide and weighed as 
cuprous sulphide. 

Process 1. — Dissolve about half a gramme of dry crystal- 
lized cupric sulphate in a small quantity of water, in a tared 
porcelain crucible or beaker, acidulate with hydrochloric 
acid, introduce a fragment or two of pure zinc, cover the 
vessel with a watch-glass, and set aside until evolution of hydro- 
gen has ceased and the still acid liquid is colorless. The 
copper is then washed with hot water by decantation until no 
trace of acid remains, the precipitate is drained, rinsed with 
alcohol, dried in the water-oven, cooled, and weighed. 

Process 2. — From a solution acidulated with sulphuric acid 
and placed in a platinum crucible, copper may be entirely 

' Communicated to the Chemical Society of London on June 17, 1903, 
Journ. Chem. Soc, 83, 969 and 974. 



DETERMINATION OF COPPER. 653 

deposited in a coherent form by a weak current of electricity, 
the crucible being connected with the zinc pole of the battery, 
a platinum spatula suspended in the solution forming the 
positive pole. The crucible may afterward be freed from 
the deposited copper by means of nitric oxide. 

Process 3. — About 0.75 gramme of cupric sulphate is !^ 

dissolved in half a litre of water, and the liquid boiled ; 
dilute solution of potassium or sodium hydroxide is then added 
until no more precipitate falls, ebullition continued for a short 
time, and the beaker set aside ; the supernatant liquid is 
decanted, the precipitate boiled with water twice or thrice, 
collected on a tilter, washed, dried, transferred to a porcelain 
crucible, the filter incinerated, added to the precipitate in the 
crucible and moistened with a drop of nitric acid; the whole 
is finally heated strongly, cooled, and weighed. This process I 

can only be employed in absence of organic substances, as 
certain organic compounds such as tartaric and citric acids 
prevent the complete precipitation of the cupric oxide. * | 

247.85 parts of crystallized cupric sulphate should yield i 

78.98 of oxide, or 63.1 of metal. | 

The cupric oxide obtained as above almost always weighs 
more than the theoretical proportion as it is practically impos- 
sible to wash it free from alkali. i 

Process 4. — About half a gramme of cupric sulphate may I 

be taken, dissolved in about 200 Cc. of water and a few drops 
of hydrochloric acid added. A solution containing equal i 

quantities of ammonium thiocyanate and ammonium (or i 

sodium) bisulphite is then added until no further precipita- j 

tion takes place. The whole is heated and after the white j 

precipitate of cuprous thiocyanate has settled, the clear liquid t 

is poured through a previously weighed filter, the precipi- j 

tate washed by decantation, transferred to the filter, washed ! 

further until no trace of chloride is found in the filtrate, dried | 

in the water-oven (or preferably in an air-bath at a tempera- ; 

ture of 110° C), cooled and weighed. 

120.77 grammes of cuprous thiocyanate (CuCNS) represent 
63.1 grammes of copper. 

The determination of copper as cuprous sulphide involves 
the use of special apparatus and the ignition of the precipitate 
with sulphur in an atmosphere of hydrogen. 



654 GRAVIMETRIC ANALYSIS. 

BISMUTH. 

Dissolve 0.3 or 0.4 of the pure bismuth subcarbonate 
(Bismuthi Subcarbonas, U. S. P.), in a very small quantity 
of hydrochloric acid, dilute with water slightly acidulated 
with hydrochloric acid, pass excess of hydrogen sulphide 
through the liquid, collect the precipitate on a tared filter, 
wash, dry at 212° F. (100° C), and weigh. The sulphide 
must not be exposed too long in the water-oven, or it will 
increase in weight owing to absorption of oxygen, hence it 
should be tested in the balance every half-hour until it no 
longer loses weight. In testing the official preparation of 
bismuth, the U. S. P. directs that certain compounds (subcar- 
bonate, subnitrate) be simply ignited in a porcelain crucible 
and the resulting bismuth oxide weighed ; and that other com- 
pounds, (citrate subgallate, etc.), be first ignited, the residue 
dissolved in nitric acid, the solution evaporated to dryness, 
and the residue ignited so as to form bismuth oxide, which is 
to be weighed. 

MERCURY. 

This element may be (1) isolated and determined in the form 
of metal, or precipitated and weighed as (2) mercurous chlo- 
ride, or (3) mercuric sulphide. 

Figs. 78, 79, 80. 




Process 1. — The process by which the metal itself is sepa- 
rated is one of distillation into a bulb surrounded by water. 
About half a metre of the difficultly fusible German glass 
known as combustion-tubing is sealed at one end after the 
manner of a test-tube (Fig. 78); a mixture of sodium bicar- 
bonate and dry chalk is then dropped into the tube to the 
height of two or three centimetres, and, next, several small 
fragments of quicklime so as to occupy another centimetre ; 



i 



DETERMINATION OE MERCURY. 



655 



a mixture of about a gramme of pure calomel or corrosive 
sublimate with enough powdered quicklime to occupy 10 or 
12 centimetres of the tube is added, then the lime-rinsings 
of the mixing-mortar, a layer for a few centimetres of pow- 
dered quicklime, and, finally, a plug of asbestos. The whole 
should occupy two-thirds of the tube. The part of the tube 
just above the asbestos is now softened in the blowpipe- 
tlame and drawn out about a decimetre to the diameter of a 
narrow quill (Fig. 79) ; again drawn out to the same extent at 
a point two or three centimetres nearer the mouth (Fig. 79) 
and any excess of tubing cut off. The bulb thus formed may 
be enlarged by softening and blowing. The tube is next 
softened at a point close to but anterior to the asbestos, and 
bent to form an obtuse angle ; the tube is then softened close 
to the bulb and slightly bent so that the bulb may be 
parallel with the long tube ; then softened on the other side 

Fig. 81. 




of the bulb, and the terminal tube bent to an obtuse angle, 
so that, the tube being held in a horizontal position, the bulb 
may be sunk in the water, and the terminal tube point upward 
(Fig. 80). The long tube is now laid in the gas-furnace 
(Fig. 81), a basin so placed that the bulb of the apparatus 
may be cooled by being surrounded by water, the part of the 
tube occupied by asbestos heated to redness, and the flame 
slowly lengthened until the tube is uniformly red-hot. In 
the circumstances just described the mercury compound is 
decomposed by the lime and its acid radical fixed, and the 
mercury carried in vapor to and condensed in the bulb. 
The carbonic anhydride evolved from the sodium bicarbonate 
and chalk washes out the last portions of mercury vapor 



656 GRAVIMETRIC ANALYSIS. 

from the tube. Wheu the distillation is considered to be 
complete, the dish of water is removed, the bulb dried, and 
then detached by help of a file, at a point beyond any sub- 
limate of mercury. The dried bulb is weighed, the mercury 
shaken or dissolved out, and the tube again dried and 
weighed. The difference between the weights gives the 
weight of the mercury. "Ammoniated Mercury," U. S. P., 
should yield 78 to 80 percent, of metallic mercury. 

Process 2. — The process by which mercury is separated in 
the form of calomel, consists in adding, in the cold, solution of 
hydrochloric and phosphorous acids to an aqueous or even 
acid solution of a weighed quantity of the mercurial com- 
pound, setting the mixture aside for twelve hours, collecting 
the precipitate on a tared filter, washing, drying at 212° F. 
(100° C), and weighing (Rose). By adding first excess of 
hydrogen peroxide, then phosphorous acid, and warming on a 
water-bath until the precipitate is flocculent, the reaction is com- 
pleted in a few minutes without reduction of calomel to 
metallic mercury as is the case when the mercuric chloride 
solution is heated with phosphorous acid. The experiment 
may be tried on about half a gramme of corrosive sublimate. 

Process 3. — Two or three decigrammes of corrosive subli- 
mate are dissolved in water, the solution acidulated with hydro- 
chloric acid, excess of hydrogen sulphide passed through it, 
the precipitate collected on a tared filter, washed with cold 
water, dried at 212° F.(100° C), and weighed. 

Proportional Weights of Equivalent Quantities of Mercury 
and its Salts. 

Mercury Hg 198.5 

Mercurous chloride . . . HgCl 233.68 

Mercuric chloride .... HgCl^ 268.86 

Mercuric sulphide . . . HgS 230. 33 

LEAD. 

Lead is generally determined either as (1) oxide, (2) sul- 
phate, (3) chromate, or (4) metal. 

Process 1. — Weigh out one or two grammes of pure lead 
acetate in a covered crucible, previously tared, and heat slowly 
until no more vapors are evolved. Remove the lid, stir down 
the carbonaceous mass with a clean iron wire, and keep the 
crucible in the flame so long as any carbon remains uncon- 
sumed. Introduce some fragments of fused ammonium nitrate, 



i 



DETERMINATION OF LEAD. 657 

and again ignite until no metallic lead remains and all excess 
of the nitrate has been decomposed. Cool and weigh the 
resulting oxide (PbO). 

Process 2. — Dissolve 0.4 or 0.5 gramme of lead acetate in 
a small quantity of water, drop in dilute sulphuric acid, add 
to the mixture twice its bulk of alcohol, and set aside. 
Decant the supernatant liquid, collect the sulphate on a filter, 
wash with alcohol, dry, transfer to a porcelain crucible, 
removing as much of the sulphate as possible from the paper, 
incinerate on the crucible-lid (not in the platinum coil, for 
the fused particles of reduced lead would alloy with the 
platinum), ignite, cool, and weigh. 

Process 3. — About half a gramme of lead acetate is dis- 
solved in two to three hundred Cc. of water, acetic acid 
added, and then solution of potassium dichromate. Collect 
the precipitate on a tared filter, wash, dry at 212° F. (100°C.), 
and weigh. 

Process 4. — In certain cases, notably in that of commercial 
'Svhite lead," the lead may be determined in the metallic 
state by means of potassium cyanide. The lead paint (about 
20 grammes) is weighed and carefully incinerated. The 
residue, a mixture of metallic lead and lead oxide, is then 
mixed with several times its bulk of potassium cyanide, and 
the whole heated to fusion. With careful manipulation the 
lead collects in one globule, which, after cooling, may readily 
be separated from the mixed cyanide and cyanate, and 
weighed. Commercially pure white lead should yield 74 per- 
cent, of lead. 

Volumetric Determination of Lead. 
In lead acetate and in the strong solution of lead subacetate 
the lead may be determined volumetrically by means of nor- 
mal solution of sulphuric acid. About 3 grammes of lead 
acetate or from 7 to 10 grammes of the subacetate solution 
may be used. 

Pb(C2H30,),,3H.p 4- H.,SO, = ThSO, + 2HC2H3O, + 3H,0 



2)376.15 2)97. 35_ 

188. 075 48. 675 ^grammes in 1000 Cc. of normal solution. 

Pb.,0(C2H302)2 + 2H.,S0, = 2PbS0, + 2HC2H3O., -f- H,0 

4)543.74 4)194.70 

135.93 48, 675 =grannncs in 1000 Cc. of normal solution. 

42 



I 



6 58 GEA VIMETRW A NA L YSIS. 

The flask iu which the operation is being conducted shoukl 
previously contain one-third of water. In the case of both 
lead acetate and solution of lead subacetate, a little acetic acid 
should be added to prevent precipitation of basic salt on dilu- 
tion. The only indicator of complete reaction is cessation of 
production of the precipitate — lead sulphate. The United 
States Pharmacopoeia requires lead acetate to contain not less 
than 99.5 percent, of pure Lead Acetate, and solution of lead 
subacetate to contain not less than 25 percent, of lead sub- 
acetate. 

Proportional Weights of Equivalent Quantities of Lead and 
of some of its Compounds. 

Lead Pb 205.35 

Lead acetate Pb(C2H302),3Hp . .376.15 

Lead oxide PbO 221.23 

Lead sulphate PbSO, 300.70 

Leadchromate PbCrO 320.57 



SILVER. 

Silver in compounds which are readily decomposed by heat 
is determined as (1) metal, in others usually as (2) chloride 
(AgCl), but sometimes as (3) cyanide (AgCN). 

Process 1. — Heat about a gramme of silver oxide, Ag^O, in 
a tared crucible, cool, and weigh. 230.12 of oxide yield 
214.24 of metal. 

Process 2. — Dissolve 0.4 or 0.5 gramme of pure dry crystals 
of silver nitrate in water, acidulate with two or three drops 
of nitric acid, slowly add hydrochloric acid, stirring rapidly, 
until no more precipitate is produced. Pour off the superna- 
tant liquid through a filter, wash the silver chloride once or 
twice with hot water, transfer to the filter, complete the v.ash- 
ing, and dry. After removing as much as possible of the 
precipitate from the paper to the crucible, burn the filter, not 
in a wire helix but on the inverted lid of the crucible, moisten 
with a drop of nitric acid, warm, add a drop of hydrochloric 
acid, evaporate to dryness, replace the lid on the crucible, 
ignite the whole until the edges of the mass of chloride begin 
to fuse ; cool, and weigh. 168.69 of nitrate yield 142.3 of 
chloride. 3 parts of Mitigated Silver Nitrate ( Ar genii Nitras 
Mitigatus, U. S. P.), similarly treated, give 0.843 parts of 
silver chloride, aud the filtrate yields potassium nitrate and 



DETERMINATION OF ACID RADICALS. 659 

chloride on evaporation. 10 parts of silver dissolved in nitric 
acid and treated as above will, if pure, give 13.285 of silver 
chloride. 

Process 3. — Silver cyanide may be collected on a tared filter 
and dried at 100° C. 168.69 of nitrate yield 132.96 of 
cyanide. 

Silver and its salts may be determined volumetrically by 
means of a standard solution of sodium chloride. 

Cupellation. — The percentage of silver in an alloy may be 
determined by a dry method. The metal is folded in a piece of 
thin sheet lead, placed on a cwpel (cupella, little cup, made 
of compressed bone-earth) and heated in a furnace, the cupel 
being protected from the direct action of the flame by a case 
termed a muffle. The metals melt, the baser become oxidized, 
the lead oxide fusing and dissolving the other oxides ; the 
fluid oxides are absorbed by the porous cupel, a button of 
pure silver remaining. An alloy suspected to contain 95 per 
cent, of silver requires about three times its weight of lead 
for successful cupellation; if 90 percent. (U. S. silver coin), 
seven times its weight of lead is necessary. 



QUESTIONS AND EXEECISES. 



Explain the gravimetric process by which the concentration of sohi- 
tions of ferric chloride, nitrate, and sulphate may be determined. — Men- 
tion the various amounts of ferrous and ferric salts equivalent to 100 
parts of iron. — State the precautions necesssary to be observed in 
determining arsenic or antimony in the form of sulphide. — In what form 
are the official compounds of bismuth weighed for quantitative purposes? 
— Give an outline of the process by which mercury may be isolated from 
its official preparations and weighed in the metallic condition, — Give three 
methods for the quantitative analysis of lead salts ; and the weights of 
the respective precipitates, supposing 0.56 grm, of crystallized acetate to 
have been operated on in each case. — Describe the processes by which 
silver is determined in the forms of metal, chloride and cyanide. — What 
proportions of silver nitrate are indicated, respectively, by 15 of metal, 
9.8 of chloride, and 8.1 of cyanide ? — Describe cupellation. 



DETEKMINATION OF ACID EADICALS. 

CHLORIDES. 

Free chlorine (chlorine-water) and compounds which by 
action of acids yield free chlorine (Chlorinated Lime, Chlorin- 
ated Soda, and their Solutions) may be determined volu- 



660 GRAVIMETRIC ANALYSIS. 

metrically by a standard solution of sodium thiosulphate (see 
p. 635). The quantity of combined chlorine in chlorides 
may be determined by volumetric analysis with a standard 
solution of silver nitrates (p. 624). 

Combined chlorine is gravimetrically determined in the form 
of silver chloride, the operation being identical with that 
described for silver salts (p. 658). 58.06 parts of pure, 
colorless, crystallized sodium chloride yield 142.3 of silver 
chloride. 

IODIDES. 

Free iodine is determined volumetrically by means of solu- 
tion of sodium thiosulphate (see p. 636). 

Combined iodine is determined gravimetrically in the form 
of silver iodide, the operations being conducted as with silver 
chloride. Potassium iodide mav be used for an experimental 
determination : KI=164.76 should yield Agl^233.02. 

Moisture in iodine is roughly determined by loss on expos- 
ing a weighed sample on a watch-glass placed in a desiccator 
over sulphuric acid. Another method consists in adding to 
a weighed sample five or six times as much mercury, or 
excess of zinc or silver filings, and a little water, drying and 
weighing. The weight of the product is the weight of metal 
employed plus that of the dry iodine in the sample. 

BROMIDES. 

Free bromine may be determined by shaking with excess 
of solution of potassium iodide, and then determining the 
equivalent quantity of liberated iodine by means of a standard 
solution of sodium thiosulphate (p. 635). 

The bromine in bromides may be precipitated and weighed 
as silver bromide, the manipulations being the same as those 
for silver chloride: 0.2 to 0.3 gramme of pure potassium 
bromide may be used for an experiment. 

CYANIDES. 

Hydrogen cyanide (hydrocyanic acid) is usually determined 
volumetrically (see p. 625). 

From all soluble cyanides cyanogen may be precipitated 
bv silver nitrate, after acidulating with nitric acid, the silver 
cvanide being collected on a tared filter, dried at 100"^ C, and 
weighed. 



DETERMINATION OF NITRATES. 



661 







Silver Cyanide. 




Silver . . 


. Ag 


In formula wt. 
107.12 . . 


In 100 parts 

. . 80.565 


Cyanogen 


, CN . 


..... 25.84 . . 


. . 19.435 






132.96 


100.00 




NITRATES. 





Nitrates cannot be determined by direct gravimetric 
analysis, none of the metallic radicals yielding a definite 
nitrate insoluble in water. With some difficulty they may be 
determined by indirect volumetric methods. 



Fig. 82. 




Determination of nitrates. 

Process. — The following (Thorpe's) method depends upon 
the fact (Gladstone and Tribe) that when zinc upon which 
copper is deposited in a spongy form is boiled with water, 
hydrogen is evolved. Thorpe found that in a solution con- 
taining nitrates the nascent hydrogen converts tlie whole of 
the nitrogen of the nitrates into ammonia, which may be 
collected and determined. (The oxygen of the nitrate is 
simultaneously converted into water, the metallic radical into 
hydroxide, and the zinc into zinc hydroxide. The power of 
the copper-zinc couple is considered to depend largely on the 
hydrogen absorbed by the finely divided metal.) 

An apparatus such as shown in Fig. 82 should be con- 
structed. A flask (about 100 Cc.) is fitted with a clean 
sound cork perforated for a delivery-tube, which should bo 



662 ■ GRAVIMETRIC ANALYSIS. 

of stroDg glass tubing of about a quarter-inch bore, and for a 
stoppered funnel, which should have about half the capacity 
of the flask. The whole is supported by a clamp or on wire- 
gauze. The outer jar shown in the figure should have a 
capacity of two or three litres, and the inner receiving-jar 
should be capable of holding 200 Cc. The latter is fitted 
with a cork perforated for the delivery-tube, and perhaps for 
another tube containing fragments of glass moistened with 
acidulated w^ater to prevent possible loss of ammonia — though 
the latter tube is found to be almost unnecessary. The addi- 
tion of wash-bottle tubes is also recommended as convenient 
for obtaining the distillate from the jar without dismounting 
the apparatus from time to time. 

A few strips of clean zinc {granulated zinc recently cleansed 
with dilute acid is best), are boiled in a beaker with a 3 per- 
cent, solution of cupric sulphate, the operation being repeated 
with a fresh portion of solution until an adherent and fairly 
thick coating of finely divided copper is deposited. The 
pieces of metal are well washed and introduced into the flask, 
which is then half filled with pure water free from ammonia. 
To avoid transference, the flask itself may be used instead of 
the beaker. The funnel also of the apparatus is filled with 
pure water. Water is now placed around the inner receiver 
in the outer jar, and, the connections being sound, heat is 
applied with the view of freeing the apparatus itself from any 
trace of ammonia. When the contents of the flask are evapo- 
rated nearly to dryness, pure w^ater is admitted from the fun- 
nel until the flask is again about half full (the funnel should 
be filled again at once), and the distillation carried on as 
before. This must be repeated until no further trace of 
ammonia is evolved, when the apparatus is ready for use. 
On each occasion that the apparatus is used it must be freed 
from ammonia in this way. A suitable quantity of the sub- 
stance to be examined is now introduced (in the case of 
potable waters the prepared solid residue from 100 Cc.) and 
water added, if necessary, until the flask is half full. Heat 
is now applied and the operation conducted in the manner 
already described until ammonia no longer comes over — a point 
which usually occurs in the case of water-residues when the 
flask has been twice or thrice charged with water and the 
pistillate is about 100 Cc. The warm water from the upper 
part of the cooling-jar may l)e removed by a siphon or other- 
wise, cold water being introduced from time to time. 



DETERMINATION OF SULPHIDES. 663 

The ammonia being all evolved, disconnect the flask and 
receiver simultaneously (unless wash-bottle tubes are fitted), 
and treat the contents of the latter by the Nessler method 
described on page 616. — Urea yields but traces of ammonia 
by this process ; and neither the sulphates nor chlorides of 
the alkali-metals affect the result. — The method is only 
applicable to highly dilute solutions of nitrates, for with more 
concentrated solutions oxides of nitrogen are formed and escape. 

SULPHIDES. 

Process 1.— Soluble sulphides {e.g., H^S, NaHS) may be 
determined volumetrically by adding to the aqueous liquid a 
measured excess of an alkaline arsenous solution of known 
concentration, neutralizing with hydrochloric acid, diluting to 
any given volume, filtering off the arsenous sulphide pre- 
cipitated, taking a portion of the filtrate equal to a half or a 
third of the original volume, and, after neutralizing with 
sodium bicarbonate, determining the residual arsenic by 
means of the standard iodine solution (.see p. 629). 

Process 2. — Sulphur and sulphides may also be quantita- 
tively analyzed by oxidizing to sulphuric acid and precipita- 
ting in the form of barium sulphate. Thus 2 or 3 deci- 
grammes of a pure metallic sulphide may be decomposed by 
careful deflagration with a mixture of potassium chlorate and 
sodium carbonate, the product dissolved in water, acidulated 
with hydrochloric acid, solution of barium chloride added, 
and the precipitated barium sulphate washed and collected 
as described in connection with the estimation of barium 
(p. 645). Many sulphides may be oxidized by heating in a 
flask with potassium chlorate and hydrochloric acid, and the 
sulphate formed is then precipitated by barium chloride. 
Experimental determinations may also be made on a weighed 
fragment of sulphur, about 0.1 gramme cautiously fused with 
a small quantity of sodium hydroxide, and the product oxidized 
while hot by the slow addition of powdered potassium nitrate 
or chlorate, or, when cold, by treatment with potassium 
chlorate and hydrochloric acid, the sulphate obtained being 
subsequently precipitated by barium chloride. 

Note. — Fusions performed over a Bunscn flame must he care- 
fully conducted; for any alkali that may creep over the side of a 
crucible will certainly absorb sulphurous anhydride Ironi tlio prid- 
ucts of combustion of the gas, and error will result. 



664 GRAVIMETRIC ANALYSIS. 

Process 3. — Soluble sulphides may also be treated with 
excess of au alkali-metal arsenite, arseuous sulphide theu be 
precipitated by the addition of hydrochloric acid, aud the 
precipitate collected and weighed with the usual precautious 
(see p. 651). 

Weights of Equivaletit Quantities of Sulphur and some of its 
Coinpounds. 

Sulphur S 31.83 

Hydrogen sulphide . . HgS 33.83 

Barium sulphate . . . BaSO, 231.75 

Arsenous sulphide . . (As2S3)-^-3 81.43 

Iron pyrites .... (FeSj ^2 59.58 

Lead sulphide ... PbS 237.18 

SULPHITES. 

Sulphites are usually determined volumetrically by means 
of a standard solution of iodine {see p. 628). Sulphites 
insoluble in water are diffused in that menstruum, hydrochloric 
acid added, and the iodine solution then dropped in. 

If necessary, sulphites may be determined gravimetrically 
by oxidation as barium sulphate. 

SULPHATES. 

These salts are always precipitated and weighed as barium 
sulphate, the manipulations being identical with those per- 
formed in the determination of barium by means of sulphates 
(see p. 645). The purity of Sodium Sulphate (Sodii Sulphas, 
U. S. P.), and the presence of not more than a given quantity of 
sulphuric acid in vinegar, may be ascertained by this process. 
Ten grains of sodium sulphate yield 7.24 of barium sulphate. 
Five ounces of vinegar should yield not more than about ^ 
gramme of barium sulphate. 

Sulphates may be determined volumetrically by means of a 
half-normal solution of pure barium chloride. 

The quantity of free sulphuric or hydrochloric acid in vin- 
egar, lemon juice, lime juice, etc., may be ascertained volu- 
metrically by adding a known quantity of standard solution 
of sodium hydroxide, evaporating to dryness, incinerating, 
dissolving in water, and by standard acid determining the 
quantity of sodium hydroxide still remaining free. The 
sodium hydroxide lost indicates the amount of free mineral acid 



DETERMINATION OF CARBONATES. 665 

(Hehner). Thresh first determines the chloride in a sample 
of vinegar, then adds a known additional amount of chloride, 
preferably in the form of barium chloride, evaporates, ignites, 
treats with water, adds sodium bicarbonate to remove excess 
of barium, filters, and again determines the chlorine. A 
loss of 70.36 of chlorine (CI2) indicates 97.35 of free sulphuric 
acid (H^SOJ. 

The method of determining free sulphuric, nitric, and 
hydrochloric acids, proposed by Spence and Esilman, is 
founded on their power of decolorizing a standard solution of 
ferric acetate. 

Proportional Weights of Equivalent Quantities of Sulphates, 

The sulphuric radical . . . . SO^ 95. 35 

Sulphuric acid H^SO, 97.35 

Barium sulphate ...... BaSO^ 231.75 

CARBONATES. 

Carbonates are usually determined by the loss in weight 
they undergo on the addition of a strong acid. 

Process 1. — A small light flask is selected — of such a size 
that it can be conveniently weighed in a delicate balance. 
Two narrow glass tubes are fitted to the flask by means of a 
cork — the one straight, extending from 
about two or three centimetres above the Fig. 83. 

cork to the bottom of the flask, the other ^ ^^^^^^^^ 

cut off close to the cork on the inside ^^^^ ^J^i ) 

and curved outward so as to carry a thin W~^^ 

drying-tube horizontally above the flask || 

(see fig. 83). The drying-tube is nearly >/ W 

filled with small pieces of calcium chlo- ^ »^ 

ride, a plug of cotton-wool at either end ^Jlc^o 

preventing escape of any fragments, and ^H^^^^fe 

is attached by means of a pierced cork to "^^^^^/^^ 

the free extremity of the curved tube of ^^SoiateT ""^ 
the flask. A weighed quantity of any 
pure soluble carbonate is placed in the flask, a little water 
added, a miniature test-tube containing sul})luiric acid lowered 
into the flask by means of a thread and supported so that the 
acid may not flow out, the cork inserted, the outer end of the 
piece of the straight glass tubing closed by a cap or a frag- 
ment of cork, and the whole weighed. The apparatus is then 



L . 



666 GRAVIMETRIC CHEMISTRY. 

inclined so that the sulphuric acid and carbonate may slowly 
interact; carbonic anhydride is evolved and escapes through 
the horizontal tube, any moisture being retained by the calcium 
chloride. When effervescence has ceased, the gas still remain- 
ing in the vessel is sucked out ; this is accomplished by fixing 
a piece of India-rubber tubing to the end of the drying-tube, 
removing the small plug from the straight tube, and aspirating 
slowly with the mouth for a few minutes. If the heat produced 
by the action of the sulphuric acid and solution is considered 
insufficient to expel all the carbonic anhydride from the liquid, 
the plug is again inserted in the tube and the contents of the 
flask gently boiled for some seconds. When the apparatus is 
nearly cold, more air is again drawn through it, and the whole 
finally weighed. The loss is due to carbonic anhydride (CO,), 
from the weight of which that of any carbonate is ascertained 
by calculation. Carbonates insoluble in water may be attacked 
by hydrochloric instead of sulphuric acid ; granulated mix- 
tures of carbonates and powdered tartaric or citric acids by 
enclosing the preparation in the inner tube and placing water 
in the flask, or vice versa. The apparatus may be modified in 
many ways to suit the requirements, convenience, or practice 
of the operator. 

Process 2. — Carbonates from which carbonic anhydride is 
evolved by heat may be determined by the loss they experi- 
ence on ignition. 

Process 3. — -Free carbonic anhydride may be absorbed by 
a solid stick of potassium hydroxide or concentrated alkali 
solution, the loss in volume of the gas or mixture of gases 
indicating the quantity originally present. 

Weights of Equivalent Quantities of Carbonic Anhydride 
and certain Carbonates. 

Carbonic anhydride CO^ 43.67 

Carbonic acid H^COg . . . . 61.55 

Anhydrous sodium carbonate . Na2C03 . . . 105.31 

Crystalline sodium carbonate . Na^COg/lOHp 284.11 

Anhydrous potassium carbonate K^COj . . . 137.27 

Calcium carbonate CaCOg . . . 99.35 

OXALATES. 

Process 1. — The oxalic radical is usually precipitated in the 
form of calcium oxalate, and weighed as carbonate, the manip- 
ulations being identical with those observed in the determina- 



DETERMINATION OF PHOSPHATES. 667 

tiou of calcium {see p. 646). The experiment may be per- 
formed on 0.3 or 0.4 gramme of pure oxalic acid, 125.1 parts 
of which should yield 99.35 of calcium carbonate. 

Process 2. — Oxalates may also be determined by conversion 
of their acid radical into carbonic anhydride, and observation 
of the loss of weight due to escape of the latter. The oxalate, 
water, and excess of black manganese oxide are placed in the 
carbonic anhydride apparatus (p. 665), a tube containing sul- 
phuric acid lowered into the flask, the whole weighed, and 
the operation completed as for carbonates. From the follow- 
ing equation it will be seen that each 87.34 parts of carbonic 
anhydride evolved indicates the presence of 125.1 parts of 
crystallized oxalic acid or an equivalent quantity of other 
oxalate : — 
Na^QO^ + MnOa 4 BH^SO, = MnSO^ + 2NaHS0, + 2H2O + 200^ 

The black manganese oxide used in this experiment must be 
free from carbonates. The quantities of the materials em- 
ployed are regulated by the size of the vessels. 

Process 3. — Oxalic acid and oxalates may be determined 
volumetrically by means of a standard solution of potassium 
permanganate {see p. 634). 

PHOSPHATES. 

Process 1. — From phosphates soluble in water the phosphoric 
radical may be precipitated and weighed in the form of mag- 
nesium pyrophosphate, the details of manipulation being simi- 
lar to those observed in determining magnesium {see p. 647). 
Half a gramme or rather more of pure dry crystallized sodium 
phosphate may be employed in experimental determinations. 
Solution of magnesium ammonio-sulphate known as Magnesia 
Mixture, (U. S. P.), is prepared by dissolving 10 parts of 
magnesium sulphate and 20 of ammonium chloride, in 80 of 
distilled water and adding 42 Cc. of ammonia water. 

Process 2.— Free phosphoric acid is most readily deter- 
mined as lead phosphate Pb^/POJ,, by evaporating it to dry- 
ness with excess of pure lead oxide and heating to dull red- 
ness. The lead oxide must be quite pure ; it should be pre- 
pared by digesting red lead in warm dilute nitric acid, wash- 
ing, drying, and heating the resulting pure-colored lead per- 
oxide in a covered porcelain crucible until it is completely 
converted into lead oxide (PbO). The increase in weight 
obtained on evaporating a given quantity of solution of phos- 



668 GRAVIMETRIC ANALYSIS. 

phoric acid with a known weight of perfectly pure lead oxide 
may be regarded as entirely due to phosphoric anhydride 
(P;0.) ; 3PbO + P,0.=Pb3(PO;)2, the actual reaction being 
3Pbd + 2H3PO, = PbgCPOj^ + 3Hp. From these equa- 
tions, and the atomic weights (see Appendix or Table on p. 
59), the percentage of phosphoric acid (H^PO^) in any 
specimen of its solution may easily be calculated. 

Process 3. — The official Calcii Phosphas Precipitatus, and 
other forms of calcium phosphate known to be tolerably free 
from iron or aluminium, may be determined by treating about 
half a gramme with hydrochloric acid somewhat diluted, filter- 
ing, if necessary, warming, adding excess of ammonia, collect- 
ing the precipitate (Ca3(POJ2)j washing, drying, igniting 
and weighing. The calcium phosphate of pharmacy, if pure, 
will in this process lose little or no weight. 

Process 4. — Insoluble phosphates in ashes, manures, etc., are 
treated as follows: The weighed material (1.0 to 10.0 
grammes) is digested in hydrochloric acid diluted with three 
or four times its bulk of water, filtered (insoluble matter and 
filter being thoroughly exhausted by water), ammonia added 
to the filtrate and washings, until, after stirring, a faint cloudy 
precipitate is perceptible, solution of oxalic acid dropped in 
until, after agitation for a few minutes, the opalescence is 
destroyed, ammonium oxalate next added, the whole warmed, 
calcium oxalate remoyed by filtration, and the filtrate con- 
centrated if yery dilute, the liquid treated with citric acid in 
such quantity that ammonia when added in excess giyes a 
clear lemon-yeUoiv solution (Warington), magnesia mixture 
poured in (as in process 1), and the precipitate of ammonium 
magnesium phosphate collected, washed, dried, and weighed, 
as already described in connection with the determination of 
magnesium. 

The concentration of pure solutions of phosphoric acid may 
be ascertained by determination of specific grayity and refer- 
ence to tables. 

Relative Weights of Equivalent Quantities of Phosphoric 
Compounds. 

Phosphoric acid H,PO, 97.29 

Maofnesium pyrophosphate ( M2:,P.,0. = 221.06) -^ 2 = 110.53 

Lead phosphate (PbgiPOJa =804.63) -^ 2 = 402.315 

Phosphoric anhvdride . . (P.A =140.94)^2= 70.47 

Calcium phosphate . . . (CaglPOJ,, = 307.98) -^ 2 = 153.99 
Calcium superphosphate . (CaH4(P04)2 = 233.38) - 2 = 116.19 



DETERMINATION OF SILICATES, 669 

QUESTIONS AND EXEECISES. 

What quantity of pure rock-salt is equivalent to 4.2 parts of silver 
chloride? Ans., 1.71. — State the percentage of real potassium iodide con- 
tained in a sample of which 8 parts yield 10.9 of silver iodide. Ans., 96.63. 
— What is the concentration of a solution of hydrocyanic acid 10 parts 
which, by weight, yield 0.9 of silver cyanide? Ans., 1.81 percent.— How 
are nitrates quantitatively determined? — By what processes may the 
quantity of a sulphide present in a solution be determined ? — How much 
real sodium sulphate is contained in a specimen 10 parts of which yield 
14.2 of barium sulphate? Ans., 86.58 percent. — Give details of the opera- 
tions performed in the quautitative analysis of carbonates. — What weight 
of carbonic anhydride should be obtained from 10 parts of acid potassium 
carbonate (or bicarbonate)? Ans., 4.39 parts. — To what operation does 
the following equation refer, and w^hat are the relative proportions of the 
reacting substances ? 

Na2C204 + Mn02 + SHaSOi = MnSOi + 2NaHS04 + 2H2O + 2CO2 

Explain the lead process for the determination of phosphoric acid. — State 
the quantity of calcium superphosphate equivalent to 7.6 parts of magne- 
sium pyrophosphate. Ans., 7.989 parts. 



SILICATES. 



Silica (Si02) may be separated from alkali-metal silicates, 
or from silicates decomposable by hydrochloric acid, by digest- 
ing the substance with hydrochloric acid at a temperature of 
70° to 80° C, until completely disintegrated, evaporating to 
dryness, heating in an air-bath to a temperature of 200° C, 
again moistening with acid, diluting with hot water, filtering, 
washing, drying, igniting, and weighing. 

DETERMINATION OF WATER. 

Water and other matters readily volatilized are most usually 
determined by the loss in weight which a substance under- 
goes on being heated to a proper temperature. Thus, in the 
Pharmacopoeia, crystalline gallic acid (C^HgOs, HgO) is stated 
to lose 9.58 percent, of its weight when dried at a temper- 
ature of 100° C, cerium oxalate (Ce2( 0,0^3, 9H2O) 53 per- 
cent, on incineration, quinine bisulphate, C„oH,,^N20.„H2SO^, 
THp 22.99 percent, at 100° C, and sodium phosphate 
(Na.^HP0,,12H.p) 62.84 percent, at a low red heat; bis- 
muth oxide heated to incipient redness should scarcely 
diminish in weight. 

Process. — One or two grammes of substance is a sufficient 
quantity in experiments on desiccation, the material being 
placed in a watch-glass, covered or uncovered porcehiin 



670 GBA VIMETRIC A NA L YSIS. 

crucible, or other vessel, according to the temperature to which 
it is to be exposed. 

Rapid desiccation at an exact temperature may be effected 
by introducing the substance into a tube having somewhat 
the shape of the letter U, sinking the lower part of the tube 
into a liquid kept at a definite temperature (using a ther- 
mometer), and drawing or forcing a current of dry air slowly 
through the apparatus. Substances liable to oxidation may 
be desiccated in a current of dried carbonic anhydride. The 
weights of the U-tube before and after the introduction of the 
salt, and after desiccation, give the quantity of water sought. 
In all cases the material must be heated until it no longer 
loses weight. Occasionally it is desirable to determine water 
directly by conveying its 'vapor in a current of air through a 
w^eighed tube containing calcium chloride, and re- weighing 
the tube at the close of the operation ; the increase shows the 
quantity of water. 

Note. — Highly dried substances rapidly absorb moisture from 
the air ; they must therefore be weighed quickly, enclosed, if pos- 
sible, in tubes (p. 640), a light stoppered bottle having a wide 
mouth, a pair of clamped watch-glasses, or a crucible having a 
tightly fitting lid. 

CARBON, HYDROGEN, OXYGEN, NITROGEN. 

The quantitative analysis of animal and vegetable substances is 
either pro.vimaie or ultimate. 

Proximate Quantitative Organic Analysis includes the determina- 
tion of water, oil, albumin, starch, cellulose, gum, resin, alka- 
loids, acids, glucosides, ash. It requires the application of much 
theoretical knowledge and manipulative skill, and cannot well be 
studied except under the guidance of a teacher. One of the best 
works on the subject is by Eochleder, a translation of whose mono- 
graphs will be found in the Pharmaceutical Journal,, vol. i., 2nd 
ser., pp. 562, 610 ; vol. ii., 2nd ser., pp. 24, 129, 160, 215, 274, 
420, 478. Another is by Prescott, ''Outlines of Proximate Or- 
ganic Analysis." The fullest is by DragendorfF, translated byH. 
G. Greenish, " Plant Analysis." 

Ultimate- Quantitative Organic Analysis can only be successfully 
accomplished with the appliances of a well-appointed laboratory 
— a good balance, a gas combustion furnace 80 to 90 centimetres 
long (p. 655), giving a smokeless flame, special forms of glass 
apparatus, etc. The theory of the operation is simple : a weighed 
quantity of a substance is completely burned to carbonic anhydride 
(002=43.67) and water (1120=17.88), and these products are 



CARBON, HYDROGEN, OXYGEN, NITROGEN. 671 

collected separately and weighed ; 11.91 parts in every 43.67 of 
carbonic anhydride are carbon, 2 parts in every 17.88 of water are 
hydrogen ; nitrogen, if present, escapes as gas. If nitrogen be a 
constituent, it may, in certain cases, be determined by strongly 
heating a second quantity of the substance with the mixture of 
sodium and calcium hydroxides known as soda-lime, when the 
nitrogen is converted into ammonia. This ammonia may be deter- 
mined volumetrically (p. 615) or it may be collected and weighed 
in the form of ammonium chloroplatinate (NH^)2 PtClg— 440.24), 
of which 27. S6 parts in every 440. 24 are nitrogen. In the case 
of certain classes of substances containing nitrogen, the whole of 
this element is not convertible into ammonia by heating with 
soda-lime. In these cases the substance is burned under such con- 
ditions that its nitrogen is obtained as gas, in which condition it is 
subsequently measured. The difference between the sum of the 
weights of hydrogen and carbon, and the weight of substance 
taken, is the proportion of oxygen in the substance, supposing 
nitrogen to be absent. If nitrogen is present, the difference be- 
tween the sum of the percentages of carbon, hydrogen, and nitro- 
gen, and 100, is the percentage of oxygen. Shortly, carbon is 
determined in the form of carbonic anhydride, hydrogen as water, 
nitrogen as ammonia, or as nitrogen gas, and oxygen by difference. 
The following is an outline of the manipulation necessary for 
the determination of carbon and hydrogen : — The burning (or 
combustion as it is usually called) of the organic substance is 
carried out by heating it in a combustion-tube of hard glass 
in a current of air previously freed from water vapor and 
carbonic anhydride. The combustion-tube has an internal 
diameter of 15-18 millimetres, and is about 90 centimetres 
long, being cut to such a length that, w^hen placed in the 
furnace, it projects about 4—5 centimetres at each side. It is 
fitted at both ends with perforated India-rubber stoppers, and 
is packed for about two-thirds of its length with granular 
cupric oxide, the column of this oxide extending from a little 
way in front of the middle of the tube to close to the further 
off end. Prior to carrying out a combustion, the tube with 
its contents is heated red-hot in the furnace and a current of 
dried and purified air or oxygen is passed through it, so as to 
effect the removal of all traces of organic matter from it and 
from the cupric oxide which it contains. The burners which 
heat the front (or inlet) portion of the tube are then turned 
out, and the front half of the tube (embracing the portion 
which is not packed with cupric oxide) is permitted to cool, 
without intermission of the air current, while the cupric oxide 
is maintained at a red heat. The weic^hed tubes in which 



672 



GRAVIMETRIC ANALYSIS. 



the water and the carbonic anhydride are to be separately 
collected are next attached to the outlet end of the combus- 
tion-tube. The imter is collected in a small U-tube packed 

Fig. 84 




Fig 



Calcium chloride tube and potash-bulbs. 

with fragments of calcium chloride, or of pumice-stone 
moistened with concentrated sulphuric acid (Fig. 84) ; the 
carbonic anhydride in a series of bulbs (Fig. 84) containing 
solution of potassium hydroxide (sp. gr. about 1.27). The 
calcium chloride tube is fitted to the combustion-tube by means 

of the perforated India-rubber stop- 
per at the outlet end, and the pot- 
ash-bulbs are attached to the 
calcium chloride tube by a short 
piece of India-rubber tubing. The 
potash-bulbs must carry a short 
light tube containing a column of 
small fragments of potassium 
hydroxide three or four centimetres 
long : this serves to arrest the 
small quantity of moisture which is 
carrried away from the solution of 
potash by the dried air which passes through it during the 
operation. The form of potash-bulbs illustrated in Fig. 84 
is that originally introduced by Liebig, but it has now been 
almost entirely superseded by improved forms. Fig. 85 
represents one of the commoner forms now in use. 

When the tube has been prepared for the combustion in 
the manner described, the w^eighed quantity (usually 0.1 to 
0.2 gramme) of the substance to be burned, contained in a 
porcelain or platinum *•' boat," is rapidly introduced into the 
combustion-tube, the stopper at the inlet end being withdrawn 
for this purpose and then replaced as soon as possible. The 
substance is now gradually and cautiously heated in the 
current of air, the furnace burners being lighted at successive 




Potash-bulbs. 



CARBON, HYDROGEN, OXYGEN, NITROGEN. 673 

intervals of a few minutes, until, eventually, the whole length 
of the combustion-tube within the furnace is red-hot. The 
tube is maintained at a red heat, and the current of air (or 
of oxygen, if necessary) is continued until the substance is 
completely burned and the products of its combustion have 
been entirely swept out of the combustion-tube and into the 
absorption apparatus. The calcium chloride tube and the 
potash-bulbs are detached, and set aside near the balance for 
some time to cool, and are then separately weighed. The in- 
crease in weight of each of the two portions of the absorption 
apparatus, due to w^ater and to carbonic anhydride respectively, 
is noted, and the percentages of hydrogen, carbon, and (by 
difference) oxygen are calculated. 

General Manipulation for the Determination of Nitrogen. 

1. Determination by Conversion into Ammonia. — The com- 
bustion-tube employed in this operation is half a metre or 
more in length, and is drawn out to the diameter of an 
ordinary quill and closed at one end, the quilled end being 

Fig. 86 




about 5 centimetres long, and bent so as to form an obtuse 
angle with the main portion of the tube. Two such tubes 
are readily made by softening in the blowpipe-flame two or 
three centimetres of the central part of a tube about a metre 
long, and drawing the halves of the tube apart, as shown in 
the above engraving (Pig. 86). The tubes are separated 
by melting the glass in the middle of the quilled portion. 
The soda-lime to be used in converting the nitrogen into am- 
monia is made by slaking quicklime with a solution contain- 
ing so much sodium hydroxide that about two parts of quick- 
lime shall be mixed with one of sodium hydroxide, drying 
the product, heating to bright redness, and finely powdering ; 
it should be preserved in a well-closed bottle. Some of the 
soda-lime is introduced into the tube, then layers of the weighed 
substance and soda-lime, thorough mixture of these being 
43 



674 GRAVIMETRIC ANALYSIS. 

eifected by means of a long copper wire having a short helix, 
a good layer of soda-lime is added, and a plug of asbestos. 
Bulbs (Fig. 87), known as those of Will and Varrentrapp 
(the originators of the method), containing hydrochloric acid 
of about 25 percent., are then fitted by means of a cork, and 
the tube is gradually heated from the outlet end, backward, 
to the closed end in the furnace — to a not too bright red heat, 
or some of the produced ammonia gas may be decomposed. 
When gas bubbles no longer pass through the bulbs and com- 
bustion is considered to be quite complete, the tube is allowed 
to cool somewhat, the quill is then broken, and air is slowly 
drawn through the tube and bulbs by means of an aspirator 

Fig. 87 




Nitrogen-bulbs. 



until all ammonia gas may be considered to have been absorbed 
by the acid. The bulbs are disconnected, their contents and 
rinsings poured into a small dish, solution of chloroplatinic 
acid added, and the operation completed as in the determina- 
tion of potassium and ammonium salts (see pp. 641 and 643). 
Or the ammonia may be absorbed in a known volume of 
standard sulphuric acid, of which the residual excess is deter- 
mined by means of a standard alkali; certain obvious calcu- 
lations then giving the quantity of ammonia produced. 

Conversion into ammonia may also be effected by heating 
the substance with the most concentrated sulphuric acid and, 
if not then thoroughly attacked, with potassium permanganate 
(Kjeldahl). 

1. Determination as Nitrogen Gas (Method of Dwnas). — 
The combustion-tube employed in making nitrogen determina- 
tions by this method (which is applicable to all classes of 
nitrogen compounds) is fitted in the same manner as that used 
in determining carbon and hydrogen (p. 671), except that the 
place of 8 to 10 centimetres of the column of cupric oxide, at 
the outlet end, is taken by a tightly rolled strip of fine copper 
wire-gauze which accurately fits the tube. The function of 



CARBON, HYDROGEN, OXYGEN, NITROGEN. 675 



this roll of metallic copper is to decompose oxides of nitrogen, 
which frequently are produced during the combustion, the 
oxygen combining with the copper while the nitrogen passes 
on. The combustion is carried out in an atmosphere of 
carbonic anhydride, and therefore the porcelain boat contain- 
ing the substance to be burned is placed in position (i. e., in 
front of the cupric oxide), while the tube is cold, and the 
whole of the air contained in the tube is displaced by means 
of a brisk current of pure carbonic anhydride while the cupric 
oxide is being heated, but before the heating of the substance 
is begun. When the air has been displaced, the narrow 
delivery-tube which is fitted into the stopper at the outlet end 
of the combustion-tube is connected with a nitrometer charged 
with a concentrated solution of potassium hydroxide. As soon 
as the cupric oxide and roll of copper gauze are distinctly 
red-hot, the substance is slowly and cautiously heated, as in 
the case of a carbon and hydrogen combustion, the whole of 
the tube within the furnace being raised, eventually, to a 
moderate red heat. A very slow current of carbonic anhydride 
is sometimes passed through the tube during the whole com- 
bustion. In the case of substances containing a large propor- 
tion of carbon, such as alkaloids, it is usually necessary to mix 
the portion taken for analysis with some finely granular cupric 
oxide in the porcelain boat, so as to ensure its complete com- 
bustion and the evolution of the whole of its nitrogen. When 
the substance is completely burned, the products of the com- 
bustion are slowly driven forward into the nitrometer by 
passing a moderate current of carbonic anhydride for some 
time. The carbonic anhydride is absorbed and the water 
vapor is condensed by the potassium hydroxide solution in the 
nitrometer, and the nitrogen is collected in a pure state. The 
volume of the gas and the temperature and pressure at which 
it was measured are noted and, from the corrected volume, the 
weight of the nitrogen and the percentage of it present in the 
substance, are ascertained by making a few simple calculations. 
Liquids are analyzed by methods similar to those adopted 
for solids, volatile liquids being enclosed in small bulbs blown 
on the end of two-inch capillary tubes. These are weighed 
previously to and after the introduction of the liquid, the end 
of each capillary tube being sealed prior to the second weigh- 
ing; just before being placed in a porcelain boat and intro- 
duced into the combustion-tube, the capillary tube is broken. 



676 GRAVIMETRIC ANALYSIS. 

Limit of Experimental Errors. — Two determinations of carbon 
may vary to the extent of 0.1 percent. ; of hydrogen, 0.2 ; of 
nitrogen, 0.3. 

Chlorine, Bromine, or Lodine, contained in an organic substance, 
may be determined by heating with fuming nitric acid and silver 
nitrate in a sealed tube, or by heating to redness a given weight 
of the material with ten times as much pure lime in a combustion- 
tube. By the latter process, calcium chloride, bromide, or iodide 
is produced. While still hot, the tube is plunged into water, the 
mixture of broken glass and powder treated with dilute nitric acid 
in very slight excess ; the filtered liquid precipitated by the addi- 
tion of excess of silver nitrate, and the silver chloride, bromide, 
or iodide collected, washed, dried, cooled, and weighed. 

Sulphur, Phosphorous, and Arsenic in organic salts may be deter- 
mined by heating with fuming nitric acid in a sealed tube, or by 
gradually heating in a combustion-tube 1 part of the substance 
with a mixture of 10 parts of nitre, 2 of dried sodium carbonate 
(in order to moderate deflagration), and 20 of sodium chloride. 
The product is dissolved in water, acidulated by the addition of 
excess of nitric acid, the sulphuric radical precipitated, and 
weighed as barium sulphate, the phosphoric and arsenic radicals 
as ammonium magnesium phosphate and ammonium magnesium 
arsenate respectively. 



SUGAR. 

The qualitative test for sugar, by means of an alkaline 
cupric solution, may be applied in the determination of sugar 
in saccharine substances. 

Process.— 34.65 grammes of pure dry crystals of ordinary 
cupric sulphate are dissolved in about 250 Cc. of distilled 
water. 173 grammes of pure crystals of potassium sodium 
tartrate are dissolved in 480 Cc. of solution of sodium 
hydroxide of sp. gr. 1.14. The solutions are only mixed when 
required, water being then added to form 1 litre; smaller 
quantities of the fluids being proportionately diluted. 100 Cc. 
of this mixture represent 3.465 grammes of cupric sulphate, 
and correspond to 0.500 gramme of pure anhydrous grape- 
sugar, 0.475 of cane-sugar, 0.807 of maltose, or 0.450 of 
starch. The solutions must be preserved in well-stoppered 
bottles to prevent absorption of carbonic anhydride, and should 
be kept in a dark place. Should the mixture give a precipi- 
tate on boiling, a few drops of sodium hydroxide solution may 
be added when making experiments. Such a reagent is known 
as Fehlhig^s solution. 



DETERMINATION OF SUGAR. 677 

Dissolve 0.475 grm. of pure powdered cane-sugar in about 
50 Cc. of water, convert into inverted sugar by acidulating 
wdth sulphuric acid and heating for an hour or two on a water- 
bath, make slightly alkaline with sodium carbonate, and dilute 
to 100 Cc. Place 10 Cc. of the cupric solution in a small 
flask, dilute with three or four times its volume of water, and 
gently boil. Into the boiling liquid drop the solution of sugar 
from a burette, 1 cubic centimetre, or less, at a time, until, 
after standing for the precipitate to subside, the supernatant 
liquid has just lost its blue color; 10 Cc. of the solution of 
sugar should be required to produce this effect — equivalent to 
0.0475 of cane-sugar, 0.0807 of maltose, or 0.0500 of grape- 
sugar. Experiments on pure cane-sugar must be practised 
until accuracy is attained ; syrups, diabetic urine, and sac- 
charated substances containing unknown quantities of sugar 
may then be analyzed. 

Starch is converted into grape-sugar by gentle ebullition 
with dilute acid for eight or ten hours, the solution being 
finally diluted so that sugar corresponding to one part of starch 
shall be contained in about 150 of water. 

If, instead of Fehling's solution, Pavy's ammoniated solu- 
tion be used (Proceedings of the Royal Society, vol. xxviii., p. 
260 ; and vol. xxix., p. 272 ; or Lancet, March 1, 1884, p. 
376 ; or Pharmaceutical Journal, 8 ser., vol. xvii., p. 856), 
one-fifth more of the cupric salt will be required for the same 
quantity of sugar. 

In cases in which loss of blue color cannot be relied on as 
indicating the termination of the reaction, the cuprous oxide 
should be rapidly filtered out, washed, dried, and ignited, the 
filter being ignited separately, to minimize the risk of reduc- 
tion, and its ash added, and the resulting black cupric oxide 
weighed. When the highest attainable degree of accuracy is 
required, it is now customary to determine the quantity of 
copper contained in the precipitated cuprous oxide by depos- 
iting it electrolytically and weighing it. One gramme of 
cupric oxide (or of cuprous oxide or of metallic copper) indi- 
cates the subjoined amounts of the respective sugars. 







Cane- 


TMilk- 


^ralt- 


One gramme of 


Glucose. 


sugar. 


sugar. 


sugar. 


Cupric oxide . . . 


. . . 4585 


— .4308 - 


- .()153 


— .7314 


Cuprous oxide . . . 


. . . 5042 


— .4790 - 


- .(^843 


— .8132 


Metallic copper . . 


. . .5634 


— .5395 - 


- .7707 


— .9089 



678 



QUANTITATIVE ANALYSIS. 



Sugar may be estimated roughly by the measurement of 
the carbonic anhydride evolved, or of the alcohol produced, 
during fermentation with yeast. In the method of Einhorn, 
a measured quantity of urine is shaken up with purified yeast 
and the mixture is introduced into a tube shaped like the 
Doremus Ureometer, figured on p. 579, which is then allowed 
to stand at the ordinary temperature for twenty -four hours. 
From the volume of carbonic anhydride evolved during the 
fermentation the quantity of sugar is calculated, or the tube 
may be so graduated as to indicate the percentage of sugar in 
the urine. Should the urine contain more than 1 percent, of 
sugar, it must be diluted and the experiment repeated. 

Saccliarimetry. — A generic term for certain quantitative 
operations, undertaken with the view of ascertaining the 
quantity of sugar present in any matter in which it may be 
contained. 

Saccharimetry is frequently performed upon common 
syrup (Syrupus, U. S. P.), and solutions which are known to 
contain nothing but ordinary cane-sugar, the object being 
merely to ascertain the quantity present. In such a case, it is 
only necessary to take the specific gravity of the liquid at 
60° F. (15.5° C), and then refer to a previously prepared 
Table of densities and percentages. 



Specific 


Cane-susjar, 


Specific Cane-sugar. 


Specific C 


gravity. 


percent. 


gravity. 


percent. 


gravity. 


1.007 


. 1.8 


1.100 


23.7 


1.210 . 


1.014 


. 3.6 


1.108 


25.4 


1.221 . 


1.022 


. 5.6 


1.116 


27.1 


1.231 . 


1.029 


. 7.3 


1.125 


29.0 


1.242 . 


1.036 


. 9.0 


1.134 


30.9 


1.252 . 


1.044 


. 10.9 


1.143 


32.8 


1.261 . 


1.052 


. 12.8 


1.152 


34.6 


1.275 . 


1.060 


. 14.7 


1.161 


36.4 


1.286 . 


1.067 


. 16.3 


1.171 


38.4 


1.298 . 


1.075 


. 18.1 


1.180 


40.1 


1.309 . 


1.083 


. 19.9 


1.190 


42.0 


1.321 . 


1.091 


. 21.7 


1.199 


43.7 


1.330 



percent. 
45.8 
47.8 
49.7 
51.7 
53.4 
55.0 
57.4 
59.3 
61.4 
63.2 
65.2 
66.6 

The specific gravity may be taken by means of a hydrom- 
eter, technicallv termed a saccharometer. 

If a liquid contains other substances besides cane-sugar, the 
test of specific o-ravity is of little or no value. Advantage 
may then frequently be taken of the fact that a solution of 
cane-sugar causes rotation of the plane of polarization of a 
rav of plane-polarized light to the right, to an extent propor- 



DETERMINATION OF ALCOHOL. 679 

tioiiate to the quantity of sugar in solution. The saccharine 
fluid is placed in a long tube having opaque sides and trans- 
parent ends ; and a ray of homogeneous light, polarized by 
reflection from a black-glass mirror or otherwise, is sent 
through the liquid and optically examined by the aid of a 
plate of tourmaline, Nicol's prism, or other polarizing eye- 
piece. Attached to the eyepiece is a short arm which traverses 
a circle divided into degrees. The eyepiece and arm are 
previously so adjusted that when the polarized ray is no longer 
visible the arm points to the zero of the scale of degrees. 
The saccharine solution, however, so rotates the plane of 
polarization of the ray as again to render it visible ; and the 
number of degrees through which the eyepiece has to be 
rotated before the ray is once more invisible is proportional 
to the quantity of sugar in the solution. The value of the 
degrees having been ascertained by direct experiment, and the 
results tabulated, a reference to the table indicates the per- 
centage of sugar in the liquid under examination. Grape- 
sugar is dextro-rotatory, but less powerfully than cane-sugar ; 
moreover, grape-sugar, unlike cane-sugar, does not suffer in- 
version on the addition of hydrochloric acid to its solution — 
an operation that furnishes data- for ascertaining the quantities 
of cane- and of grape-sugar, or of crystallizable and non-crystal- 
lizable sugar, present in a mixture. In using the polariscope 
in saccharimetry, it is convenient to employ tubes of uniform 
size, and always to operate at the same temperature. Various 
modes are adopted of applying for quantitative purposes this 
action of cane-sugar and other varieties of sugar on polarized 
light. 

ALCOHOL. 

Mulder's process for the approximate determination of the 
quantity of alcohol in wine, beers, tinctures, and other alco- 
holic liquids containing vegetable matter, is as follows : — 
Take the specific gravity and temperature of the liquid, and 
measure off* a certain quantity (100 cubic centimetres) ; 
evaporate to one-half or less, avoiding ebullition in order that 
particles of the material may not be carried away by the 
steam. Dilute with water to the original volume, and take 
the specific gravity at the same temperature as before. Of 
the figures representing the latter specific gravity, all over 
1.000 shows to what extent dissolved solid matter affected the 
original specific gravity of the liquid. Thus, the specific 
gravity of a sample of wine at 15-5° C, is 0.9951; evaporated 



P 



680 DIALYSIS. 

until all alcohol is removed, aud then diluted with water to the 
original volume, the specific gravity at 15.5°C. is 1.0081 ; 
and 1.0081—1.000=0.0081, which latter figure represents the 
effect of the dissolved solid matter in 0.9951 part of the orig- 
inal wine. 0.0081 subtracted from 0.9951 leaves 0.987, which 
is the specific gravity of the alcohol aud water of the wine. 
Or, divide the specific gravity of the wine by the specific 
gravity of the wine minus alcohol, carrying out the division 
to four places of decimals ; the quotient shows the specific 
gravity of the water and alcohol only of the wine. On refer- 
ring to a table of the strengths of diluted alcohol of different 
specific gravities, 0.987 at 15.5° C. is found to indicate a 
spirit containing 8 percent, of alcohol. If the removal of the 
alcohol from the wine be conducted in a retort, the liquid 
being boiled and the steam carefully condensed ; and the dis- 
tillate be diluted with water to the original volume of the 
wine operated on, the resulting mixture will furnish a liquid 
which still more accurately represents the original wine in the 
proportion of alcohol which it contains. The number in the 
table corresponding to the specific gravity of this liquid then 
shows the percentage of alcohol present in the wine. 



DIALYSIS. 
Dialysis (from oca, dia, through, and Xoffcc, lusis, a loosing or 
resolving) is a term applied by Graham to a process of anal- 
ysis by diffusion through a porous septum. The apparatus 
used in the process is called a dicdyzer, and is constructed aud 
employed in the following manner : The most convenient 
septum is the commercial urticle kno^vn as parchment paper, 
made by immersing unsized paper for a short time in sul- 
phuric acid and then thoroughly washing it in water. A 
piece of this material is stretched over a gutta percha hoop, 
and secured by a second external hoop. Dialyzers of useful 
size are one or two inches deep and five to ten inches wide. 
Liquids to be dialyzed are poured into the dialyzer, which 
is then floated in a flat dish containing distilled water. The 
portion passing through the septum is termed the difusafe, 
the portion which does not pass through is termed the dialy- 
sate. 

The practical value of dialysis depends upon the fact that 
certain substances diffuse through a given porous septum far 
more rapidly than others. Uncrystallizable substances diffuse 



CONCLUSION. 681 

very slowly. Of such substances as starch, gum, albumin and 
gelatin, the last named is one of those which diffuse most 
slowly ; hence substances of this class are termed colloids, or 
bodies like collin, which is the soluble form of gelatin. Sub- 
stances which diffuse rapidly are mostly crystalline ; hence 
bodies of this class are termed crystalloids. 

By the aid of dialysis it is possible to separate small quanti- 
ties of crystalloid substances from the large quantities of 
colloid matter often present in vegetable and animal liquids. 



QUESTIONS AND EXEECISES. 



Write a few paragraphs descriptive of the process of ultimate organic 
analysis. — In what forms are carbon, hydrogen, and nitrogen weighed in 
quantitative organic analysis? — In the combustion of 0.41 gramme of 
sugar, what weights of products will be obtained? Ans., 0.632 gramme 
of carbonic anhydride (CO,) and 0.237 gramme of water (HgO). — Mention 
the operations necessary for the determination of the proportion of sugar 
in saccharated iron cart)onate, or in a specimen of diabetic urine. — What 
is understood by saccharimetry ? — Give two processes for the estimation of 
the percentage of alcohol in tinctures, wines, or beer. — Define dialysis. 



CONCLUSION. 



Detailed instructions for the quantitative analysis of pot- 
able water, articles of food, general technical products, special 
minerals, soils, manures, air, illuminating agents (including 
solid fats, oils, spirits, petroleum, and gas), dyes, and tanning 
materials, would scarcely be in place in this volume. 

The course through which the reader has been conducted 
will, it is hoped, have taught him the principles of the science 
of chemistry, and have given him special knowledge concern- 
ing the applications of that science to medicine and pharmacy, 
as well as have imparted sufficient manipulative skill to meet 
the requirements of manufacture or analysis. The author 
would venture to suggest that this knowledge be utilized, not 
only in the way of personal advantage, but in experimental 
researches on chemical subjects connected with pharmacognosy, 
pharmacology, therapeutics, and pharmacy. The discovery 
and publication of a new truth, great or small, is the best 
means whereby to aid in advancing the calling in which we 
may be engaged, increase our own reputation, and contribute 
to that " ultimate end of knowledge " which Bacon described 
as " employing the Divine gift of reason to the use and bene- 
fit of mankind." 



682 



THE ELEMENTS. 



THE ELEMENTS. 



Names. 



'Aluminium 

Antimony 

^rgon 

Ai-senium 

Barium 

Bismuth 

Boron 

Bromine 

Cadmium 

Caesium 

Calcium 

Carbon 

Cerium 

Chlorine 

Chromium 

CobaU 

. Columbium (Niobium) 

Copper 

Erbium 

Fluorine 

Gadolinium 

Gallium 

Germanium .... 

Glucinum (Beryllium) 

Gold 

Helium 

Hydrogen 

Indium 

Iodine 

Iridium 

Iron 

Krypton 

Lanthanum 

Lead . 

Lithium 

Magnesium 

Manganese .... . 

Mercury 

Molybdenum .... 

Neodymium .... 

Neon 

Nickel 

Nitrogen 

Osmium 





International 


Symbols. 


Atomic Weights. 




H == 1 1 


= 16 


Al 


26.9 


27.1 


Sb 


119.3 


120.2 


A 


39.6 


39.9 


As 


74.4 


75.0 


Ba 


136.4 


137.4 


Bi 


206.9 


208.5 


B 


10.9 


11 


Br 


79.36 


79.96 


Cd 


111.6 


112.4 


Cs 


131.9 


132.9 


Ca 


39.8 


40.1 


C 


11.91 


12.00 


Ce 


139.2 


140.25 


CI 


35.18 


35.45 


Cr 


51.7 


52.1 


Co 


58.56 


59.0 


Cb 


93.3 


94 


Cu 


63.1 


63.6 


E 


164.8 


166 


F 


18.9 


19 


Gd 


155 


156 


Ga 


69.5 


70 


Ge 


71.9 


72.5 


Gl 


9.03 


9.1 


Au 


195.7 


197.2 


He 


4 


4 


H 


1.000 


1.008 


In 


113.1 


114 


I 


125.90 


, 126.85 


Ir 


191.5 


' 193.0 


Fe 


55.5 


55.9 


Kr 


81.2 


81.8 


La 


137.9 


138.9 


Pb 


205.35 


206.9 


Li 


6.98 


7.03 


Mg 


24.18 


24.36 


Mn 


54.6 


55.0 


Hg 


198.5 


200.0 


Mo 


95.3 


96.0 


Nd 


142.5 


143.6 


Ne 


19.9 


20 


Ni 


58.3 


58.7 


N 


13.93 


14.04 


Os 


189.& 


1 191 



THE ELEMENTS. 
The Elements {continued). 



683 



Names. 



Oxygen .... 

Palladium . . 

Phosphorus . . 

Platinum . . 

Potassium . . . 
Praseodymium 

Kadium . . . 

Rhodium . . 

Eubidium . . 

Ruthenium . . 

Samarium . . 

Scandium . . 

Selenium . . . 

Silicon . . . . 

Silver . . . . 

Sodium . . . 

Strontium . . 

Sulphur . . . 

Tantalum . . 

Tellurium . . 

Terbium . . . 

Thallium . . . 

Thorium . . . 

Thulium . . . 

Tin .... . 

Titanium . . . 

Tungsten . . . 

Uranium . . 

Vanadium . . 

Xeonn . . . , 

Ytterbium . . 

Yttrium . . . 

Zinc 

Zirconium . . 





International 


'mbols. 


Atomic Weights. 




H =1 


= 16 





15.88 


16.00 


Pd 


105.7 


106.5 


p 


30.77 


31.0 


Pt 


193.3 


194.8 


K 


38.86 


39.15 


Pr 


139.4 


140.5 


Ea 


223 


225 


Rh 


102.2 


103.0 


Rb 


84.8 


85.4 


Ru 


100.9 


101.7 


Sm 


148.9 


150 


Sc 


43.8 


44.1 


Se 


78.6 


79.2 


Si 


28.2 


28.4 


Ag 


107.12 


107.93 


Na 


22.88 


23.05 


Sr 


86.94 


87.6 


S 


31.83 


32.06 


Ta 


181.6 


183 


Te 


126.6 


127.6 


Tb 


158.8 


160 


Tl 


202.6 


204.1 


Th 


230.8 


232.5 


Tm 


169.7 


171 


Sn 


118.1 


119.0 


Ti 


47.7 


48.1 


W 


182.6 


184.0 


U 


236.7 


238.5 


V 


50.8 


51.2 


X 


127 


128 


Yb 


171.7 


173.0 


Yt 


88.3 


89.0 


Zn 


64.9 


65.4 


Zr 


89.9 


90.6 



I 



» 



INDEX 



A 



Abies balsamea, 415, 478 

Abrin, 501 

Abrus precatorius, 501, 547 

Absinthe, 496 

Absinthin, 496 

Absolute alcohol, 423, 595, 600 

temperature, 46 
Absorption spectrum, 559 
Acacia, 121, 494 

catechu, 342 

suma, 342 
Acacios cortex, 343 
Acalypha, 526 
Acalyphine, 526 
Acetal, 450 
Acetaldehyde, 448 
Acetamide, 408 
Acetanilide, 408 
Acetanilidum, 408 
Acetate, ammonium, 95, 282 

amyl, 404 

calcium, 281 

copper, 184 

ethyl, 283, 403 

ferric, 158, 284 

lead, 223 

mercurous, 284 

morphine, 282, 514 

potassium, 74 

silver, 284 

sodium, 87, 281 

zinc, 135 
Acetates, 281 

analytical reactions of, 283 

decomposition of aqueous solu- 
tions of, 282 

distinction of, from meconates 
and thiocyanates, 333, 345 
Acetic acid, 281, 283, 448 
glacial, 283 

volumetric determination 
of free, 622 

anhydride, 282 

ether, 283, 403 

series of acids, 448 

relations of, 455 
Aceto-acetic acid in urine, 581 
ether, 404 



Acetone, 283, 464 

in urine, 580 

iodoform test for, 580 
Le Nobel's test for, 580 
Acetonitrates, ferric, 162 
Acetonitrile, 447 
Acetonum, 464 
Acetophenone, 464 
Acetoximes, 510 
Acetpheiietidin, 408 
Acetphenetidiyium, 408 
Acetum opii, 282 

scillse, 282 
Acetyl, 282 

benzaconine, 527 

chloride, 282 

salicylic acid, 458 
Acetylene, 395 

series of hydrocarbons, 394 
Acetylenes, relations to paraffins 

and olefines, 394 
Acetylide, copper, 395 
Acetylides, 395 
Acichlorides, 169, 273 
Acid anhydrides, 65 

character, 66 

potassium sulphate, 272 
tartrate, 79, 83, 305 

radical, 65 

radicals, qualitative detection 
of, 348 
quantitative determination 

of salts of. 659 
tables to aid in the detec- 
tion of, 351, 352 

reaction, 65 

salts, 66, 78, 79 

sodium sulphate, 253 

solution of arsenic, 174 
Aeidimetry, 621, 624 
Acidity of bases, 6G 
Acids, acetic series, 448 

acrylic series, 455 

analytical detection of, 348 

benzoic or aromatic series, 456 

basicity of, 66, 251 

cinnamic series, 460 

classes of, 65 

685 



i 



686 



INDEX, 



Acids, concentration of, 251 
dibasic, 66, 461 
free, determination of, 621 
glyoxylic series, 455 
hexabasic, 462 
hydroxybenzoic series, 457 
lactic series, 453 
malic series, 461 
of chlorine, 280 
of phosphorus, 336 
of sulphur, 296 
organic, 446 
phthalic series, 462 
polybasic, 462 
properties of, 65 
"strength" of, 251 
strong, 251 
succinic series, 463 
sulphouic, 428 

table showing relations of ace- 
tic, lactic, and 
glyoxylic, 455 
acetic and dibasic 
series, 463 
tartaric series, 462 
tetrabasic, 462 
tribasic, 462 

trihydroxybenzoic series, 459 
weak, 251 
Acidum aceticum, 283 

dilutum, 283 

glaciale, 283 
benzoicum, 321, 456 
boricum, 319 
camphor icum, 473 
citricum, 308 
gallicum, 343 
hydriodicum dilutum, 260 
hydrobromicum dilutum, 257 
TiydrocMoricum, 35, 253 

dilutum, 253 
hydrocyaniaim dilutum, 267 
hypophosphorosum, 329 

dilutum, 329 
lacticum, 331 
nitricum, 272 

dilutum, 272 
nitro-hydrochloriacm, 273 

dilutum, 273 
oleicum, 439 
phosphorieum, 313 

dilutum., 313 
snlicylicum, 457 
stearicum, 453 
sulphuricum, 293 

aromaticum, 293 

dilutum, 293 
sulphurosum, 288 
tannicum, 340 



Acidum tartaricum, 300 

trichloraceticum, 451 
Acipenser, 547 
AcoJcanthera, 502 
Aconine, 526 
Aconite, 526 
Aconitia, 526 
Aconitic acid, 309 
Aconitina, 526 
Acouitine, 526 
Aconitum, 526 

ferox, 527 

heterophyllum, 527 

napellus, 526 
Acorin, 470 
^corits calamus, 470 
Acriuyl iso-thiocyanate, 427 
Acrolein, 437, 455 
Acrose, 481 
iS-Acrose, 484 
Acrylaldehyde, 437, 455 
Acrylic acid, 455 
Actea racemosa, 507 
Adeps, 442 

benzoinatus, 442 

lanx, 440 

hydrosus, 440 
Adhatoda, 540 

vasica, 540 
Adraganthin, 494 
Advice to students, xiii, 366 
^gle Marmelos, 495 
Aerated bread, 485 

water, 299 
^sculin, 535 
^Ether, 431 

acetic-US, 403 
JEthylis carbamas, 455 

chloridum, 398 
Affinity, chemical, 50 
Agate, 337 
Agropyrum, 507 
Air, composition of, 32 

gas burner, 28 

influence of animals and plants 
on, 25 

nitrogen in, 31, 32 

oxygen in, 24, 32 

ozonized, 261 

relative volumes of chief con- 
stituents of, 32 

weight of 1 cubic centimeter, 
605 
of 100 cubic inches, 606 
Ajowan oil, 466 
Ajwaiu oil, 466 

flowers of, 466 
Ajwaiiika-phul, 466 
Alabaster, 112 



INDEX. 



687 



Alantic acid, 468 
Alautol, 468 
Albumens, 546 
Albumin, 542 

detection of, in urine, 575 

test solution, 542 

vegetable, 546 
Albuminoids, 542 
Albumins, 546 
Albuminuria, 576 
Albumoses, 546, 549 
Albumosuria, 576 
Alchemy, 18 
Alcohol, 419, 422 

absolute, 423, 595, 600 

absolidum, 423 

allyl, 426 

amyl, 346, 424 

varieties of, 425 

benzyl, 435, 460 

butyl, 347, 424 

ceryl, 426 

cetyl, 425 

cinnam^yl, 460 

decylene, 427 

dilutum, 423 

ethyl, 419 

from sugar, 420 

hydroxybenzyl, 437 

in bread, 420 

melissyl, 426 

methyl, 418 

myricyl, 426 

phenic, 432 

propenyl, 437 

propyl, 424 

purity of, 419, 424, 628 

quantitative determination of, 
679 

sal icy 1, 437 

tests for, 423 

tolyl, 435 

various strengths of, 422 
Alcoholates, bromal, 453 

chloral, 449, 453 
Alcoholic beverages, 422 

fermentation, 420 
Alcoholometer, 601 
Alcohols, 416 

allyl series, 426 

aromatic, 432 

diatomic, 417, 435 

dihydric, 417, 435 

ethyl series, 417 

hexahydric, 445 

monatomic, 417 

monohydric, 417 

naphthyl, 411 

pentahydric, 445 



Alcohols, polyhydric, 445 

primary, 417 

general method of prepar- 
ing, 417 

secondary, 417 

tertiary, 417 

tetrahydric, 445 

triatomic, 437 

trihydric, 437, 445 
Aldehyde, 446, 448 

acrylic, 437 

-ammonia, 449 

benzoic, 322, 409, 435, 456, 497 

cinnamic, 460, 467 

cuminic, 468 

euodic, 470 

formic, 200, 448 

glycollic, 446 

heptoic, 468 

lauric, 470 

methylprotocatechuic, 459 

orthohydroxybenzoic, 458 

oxalic, 446 

parahydroxybenzoic, 458 

protocatechuic, 458 

salicylic, 437, 458 

test for, 449 
Aldehydes, 446 

general formation, 446 
reactions, 447 
Aldoses, 481 
Aldoximes, 510 
Ale, 422 

Alexandria senna, 498 
Aliphatic compounds, 374 
Alizarate, potassium, 411 
Alizarin, 411, 552 
Alkalies, 64 

analytical separation of the, 
106 

quantitative determination of 
the, 614 
Alkalimetry, 620 

Alkaline carbonates, volumetric 
determination of the, 618 

earths, 129 

reaction, 64 

solution of arsenic, 174 
Alkaloids, 508 

animal, 510 

antidotes to the, 513 

constitution, 508 

nomenclature of, 513 

poisonous, examination for, 555, 
et seq. 

plant, 510 

reagents for, 570 
Alkanet, 552 
Alkanna tinctoria, 552 



i 



688 



INDEX. 



Alkannin, 552 

Alkyl salts, 447 

Allotropic substances, 285 

Allotropy, 285 

Alloxau, 346 

Alloy, 209 

Allyl alcohol, 426 

cyanide, 427 

iso-thiocyauate, 427 

propyl disulphide, 427 

series of alcohols, 426 

thiocvanate (iso-), 427 
Allyleue,'394 
Almond oil, 444 

Almonds, oil of bitter, 322, 435, 456, 
466, 497 
test for nitrobenzene in, 
498 

water of bitter, 268 
Aloe, 413 

purificata, 413 
Aloes, 413 

purified, 413 
Aloins, 413 

formulae of, 414 
Aloinum, 413 
Alpha-naphthol, 411 
Alstonia consiricta, 534 

scholaris, 534 
Alstonicine, 534 
Alstonine, 534 
AWixa, 494 
Alum, 146 

ammonia, 147 

cake, 147 

chrome-, 147, 168 

dried, 147 

flour, 146 

iron-, 147 

potash-, 147 

roche or rock, 147 

root, 343 

shale, 146 

sodium, 146 
Alnmen, 146 

exsiccatum, 147 
Alumina, see Aluminium oxide. 
Alumini hydroxidum, 148 

sulphas, 147 
Aluminium, 146 

acetate, 148 

analytical reactions of. 148 

and ammonium sulphate, 146 

and potassium sulphate, 146 

and sodium, double chloride, 
146 
fluoride, 146 

bronze, 146 

chloride, 146 



Aluminium, detection of, in pres- 
ence of iron and chromium, 
107, 171 

hydroxide, 148 

oxide, 146, 147 

quantitative determination of 
649 

separation of, from chromium 
and iron, 170, 171 

silicate, 146, 337 

steel. 146 j 

sulphate, 147 
Alums, 146 
Amalgam, 209 

ammonium, 94 

electric, 209 

sodium, 94 

tin, 193 
Amalgamation, gold, 197 
Amber, 339 

oil of, 339 
American pennyroyal, 469 

turpentine, 415 

wormseed, 471 
Amethyst, 146 
Amianth, 337 
Amides, 408 
Amido-acetic acid, 550 
Amido-acet-phenetidin, 408 
Amido-benzene, 511 
Amido-succiuamic acid, 461 
Amines, 408, 508 

analogues of, 509 

constitution of, 408 
Amiuo-bases, 509 
Ammonia, 93, 94 

acetate, 

benzoate, 

carbonates, 

citrate, 

detected by Nessler's test, 616 

gas, composition of, 95 

in drinking water, 616 

nitrate, ') Old names for 

oxalate, > ammonium salts, 

phosphate, J which see. 

preparation of, 94 

solution of, 95 

sulphate, see Ammonium salts 

yolcanic, 94 

yolumetric determination of 
solutions of, 615 

water. 94 
Ammoniacal liquor. 94 

salts, sources of, 93 
Ammoniacum, 479 
Ammoniee spiritns aromaticus, 97 
Ammoniated mercury, 218 
yarieties of, 218 



Old names for 
ammonium salts, 
which see. 



INDEX. 



689 



Ammonii acetatis liquor, 96 
benzoas, 98, 322 
bromicluin, 98, 257 
carhonas, 96 
cliloridum, 94 
iodidum, 98 
valeras, 347 
Ammonio-cliloride, mercury, 218 
-citrate, iron, 159 
sulphate, magnesium, 667 
tartrate," iron, 161 
Ammonium, 93 

acetate, 95, 282 
aluminium sulphate, 146 
amalgam, 94 

analytical reactions of, 102 
and bismuth, citrate, 230 
arsenate, 175 
aspartate, 332 
benzoate, 98, 322 
bicarbonate, 96 
bromide, 98, 257 - 
carbamate, 96 
carbonate, 96 

commercial, 96 

test solution, 97 
chloride, 93 

chloroplatinate, 102, 201 
citrate, 98 
cyanate, 324 
derivation of word, 37 
dichromate, 167 
ferric sulphate, 147 
ferrous sulphate, 151 
fluoride, 328 
formate, 268 
hydrosulphide, 99, 287 
hydroxide, 94 
hypophosphite, 329 
magnesium arsenate, 127 

phosphate, 126, 315 

sulphate, 667 
molybdate, 316 
nitrate, 97, 271, 273 
nitrite, 334 
oxalate, 98 

test solution, 99 
persulphate, 295 
phosphate, 98 

potassium, sodium, and lith- 
ium, separation of, 106. 
quantitative determination of, 

644 
salts, source of, 93 

volatility of, 102 
succinate, 332 
sulphate, 94 
sulphide, 99 

test solution, 99 

44 



Ammonium, urate, 316 

valerate, 347 

volumetric determination of 
carbonate of, 617 
Amomum melegueta, 469 
Amorphous carbon, 297 

cinchona alkaloid, 522 

meaning of, 82 

phosphorus, 313 

sulphur, 285 
Amphicreatinine, 510 
Amrad, 494 
Amygdala amara, 44:4:, 497 

dulcis, 444, 497 
Amygdalin, 497 ' 

Amyl, acetate, 404 

alcohols, 346, 424 

nitrite, 334, 405 

valerate, 347, 405 
Amylene, 392 

hydrate, 425 
Amylis nitris, 335, 405 
Apyloids, 487 
Aniyl(3tlytic enzyme, 549 
Ai£ylopsin, 549 
Amyloses, 487 
Amylum, 487 
Amyric acid, 478 
Amyrin, 478 
Anacydus pyrethrum, 476 
Analogies between chlorine, bro- 
mine, and iodine, 264 
Analogy of carbon and silicon, 339 

of sodium and potassiumsalts, 92 

of nitrogen, phosphorus, arsenic 
and antimony, 122, 317, 509 
Analysis, blowpipe, 355, 356 

gas, 344, 558 

gravimetric, 610, 638 

meaning of word, 50 

of insoluble substances, 360, 
et seq. 

of medicines, 558 

of salts, 354 

of substances having unknown 
properties, 556 

organic (qualitative), 370 

proximate, 670 

quantitative, 609 

spectrum, 250, 559 

systematic, for the detection 
and sepai-ation of the metals, 
105, 106. 127, 144, 170, 202, 
239, 242 

ultimate, 670 

volumetric. (>10, 611 
Analytical detection of the acid 
radicals of salts soluble iu water, 
348 



690 



INDEX. 



Analytical memoranda, 246 
Anamirta paniculata, 502 
Auamirtin, 503 
Anchusa tinctoria, 552 
Aiichusin, 552 
Androgr aphis, 507 

caules et radix, 507 

paniculata, 507 
Andrupocfon citratus, 471 

nardas, 468 

schcenanthus, 469 
Anemone, 469 
Anemonic acid, 469 
Aiiemonin, 469 
Aneroid barometer, 45 
Anethol, 466 
Angelate, potassium, 466 
Angelic acid, 466 

powder, 187 
Angelica, 479 
Angostura bark, false, 524 

true, 534 
Angosturin, 534 
Anhydride, acetic, 282 

antimonic, 188 

arsenic, 176 

arsenous, 173, 174 

boric, 318 

carbonic, 298 

chlorochromic, 169, 263 

chromic, 166. 168, 263 

molybdic, 316 

nitric, 273 

nitrous, 274, 275 

persulphuric, 295 

phosphoric, 31, 313, 333 

phthalic, 411, 462 

silicic, 338, 339 

stannic, 194 

sulphocarbouic, 302 

sulphuric, 291, 293 

sulphurous, 213, 285, 288 

thiocarbonic, 302 
Anhydrides, 90, 282 
Anhydrochromate, potassium, 167 

silver, 238 
Anhydrochromic acid, 167, 168 
Anhydro-ecgonine, 528 
Anhydrosulphites, 289 
Anhydrous arsenous acid, 173 

chromic acid, 166, 168 

cupric sulphate, 206 

ferric chloride, 155 

ferrous chloride, 156 

salts, 90 

stannic sulphide, 196 
Aniline, 407, 511 

blue, 555 

colors, 555 



Aniline green, 555 

red, 555 

yellow, 555 
Animal alkaloids, 510 

charcoal, 297 

decolorizing power of, 298 
purified, 297 

rouge, 323, 553 

starch, 491 
Animals and plants, complementary 

action of air, 24 
Anise-fruit, 466 

-oil, 466 
Annatto, 552 
Anode, 68 

Anodyne, Hoffmann's, 432 
Anogeissus latifolia, 494 
Anthemen, 466 
Anthemis, 466, 507 

nobilis, 466 
Anthion, 296 
Anthracene, 411, 552 
Anthracite, 193 
Anthraquinone, 411 
Antichlor, 289 
Antidotes to alkaloids, 513 

antimony, 192 

arsenic, 158, 185 

barium. 111 

carbolic acid, 434 

copper, 208 

cyanides, 270 

hydrochloric acid, 255 

hydrocyanic acid, 270 

lead, 226 

mercury, 221 

nitric acid, 276 

oxalic acid, 304 

prussic acid, 270 

salt of sorrel, 304 

silver, 238 

sulphuric acid, 294 

tin, 197 

zinc, 137 
Antifebrin, 408 

Antimonial poisoning, antidotes, 
192 

wine, 189 
Antimonic anhydride, 188 

chloride, 187 

oxide, 188 

sulphide, 189 
Antimonii et potassii tartras, 188 
Antiraonious chloride, 186 

oxide, 123, 187 

oxychloride, 187, 191 

salts, analytical reactions of, 
190 

sulphide, 186, 189, 190, 203,etseq. 



INDEX. 



691 



Antimonium et potassii tartras, 188 

quantitative determination 
of antimony in, 652 
Antimoniuretted hydrogen, 191 
Antimony, 172, 186 

analytical reactions of, 190 

and potassium tartrate, 188 

and tin, separation of, 197 

antidotes to, 192 

arsenic and tin, analytical sep- 
aration, 202, et seq 

black, 186 

purified, 186 

bromide, 186 

butter of, 187 

chloride, 186 

solution, 186 

crocus, 186 

crude, 186 

derivation of word, 37 

from arsenic, to distinguish, 
190, et seq., 202 

glass, 186 

hydride, 191, 204 

in organic mixtures, detection 
of, 561 

iodide, 186 

Marsh's test for, 191, 204 

oxides, 187 

oxychloride, 187, 191 

oxysulphides, 189 

pentachloride, 187 

quantitative determination of, 
630, 652 

sulphide, 186, 189, 190, 203 

sulphur salts of, 189 

sulphurated, 189 

tannate, 342 

tartarated, 188 

tetroxide, 188 

volumetric determination, 630 
Antimonyl, 188 
Antipyrin, 408 
Antipyrina, 408 
Antiseptic, 319, 434, 437, 457 
Apatite, 318 
Apocynum, 507 

Apomorphinx hydrochloridim, 517 
Apomorphine, 516, 541 
Aporetin, 412 
Apparatus, xiv, xv, 19 

for experiments, xiv 

for volumetric analysis, 612 

lists of, xiv 
Apple-essence, 405 

oil, 405 

wine, 422 
Aqua ammouiie, 95 
fortior, 95 



Aqua amygdalae, aynarx, 497 

anisi, 465 

aurantii florum, 465, 467 
fortior, 467 

camphorse, 472 

chloroformi, 400 

cinnamomi, 465 

creosoti, 434 

destillata, 131 

foeniculi, 465 

fortis, 273 

duplex, 273 
simplex, 273 

hamamelidis, 507 

hydrogenii dioxidi, 109 

menthse piperita, 465 
viridis, 465 

regia, 203, 273 

rosse, 465, 469 
fortior, 470 
Arabic acid, 494 
Arabin, 121, 494 
Arabinose, 481 
Arachidic acid, 455 
Arachin, 444 
Arachis, 444 

hypogsea, 444 

oil, 444 
Arbor Dianse, 238 
Arbutin, 342, 498 
Archil, 554 
Arctiu7)i lappa, 507 
Arctostaphylos, uva ursi, 498 
Are, 41 
Areca catechu, 342 

nuts, 342 
Arecaine, 343 
Arecoline, 342 
Arekane, 342 
Areometers, 601 
Argal, 305 

Argent-ammonium-nitrate, 236 
Argenti cyanidum, 237, 268 

nitras, 235 
fusus, 235 
mitigatns, 236 

oxidum, 236 
Argentic chloride, sulphide, etc., 

see Silver Salts. 
Argentiferous galena, 233 
Arqeiitiim, 39 
Argol, 305 
Argon, 32, 33, 37 
Aristolochia, 527 

reticulata, 527 

serpentaria 527 
Aristolocliin, 527 
Aristolochino, 527 
Armenian bole, 552 



;/ 



692 



INDEX. 



Arnatto, 552 
Arnica, 474 
Arnicin, 474 
Arnotto, 552 
Aromatic alcohols, 432 
compounds, 374 
glycols, 43(5 

series of hydrocarbons, 406 
sulphuric acid, 293 
Arrhenal, 323 
Arrowroot-starch, 490 (fig.) 
Arsenate, ammonium, 175 
magnesium, 127 
barium, 185 
calcium, 185 
copper, 184, 208 
iron, 176, 185 
silver, 184, 237 
sodium, 176 

methyl, 323 

volumetric determination 
of, 629 
zinc, 185 
Arsenates, 175, 317 
Arseni iodidum, 173 

trioxidiun, 173 
Arsenic, 37, 172, 173, 174 
acid, 175 

analytical reactions of, 177 
and arsenical solutions, volu- 
metric determination of ofii- 
cial, 629 
and phosphorus, similarity of 

compounds, 176 
anhydride, 176 
antidotes, 158, 185 
antimony, and tin, analytical 

separation of, 202, et seq 
arsenoHS and arsenic com- 
pounds, 175, 182, 183, 185 
Berzelius's test for, 177 
Bettendorff's test for, 182 
derivation of word, 37 
detection of, in metallic copper, 
179 
in organic mixtures, 561 
Fleitmann's test for, 181 
from antimony, to distinguish, 

190, et seq., 202 
Gutzeit's test for, 182 
hydride, 204 

Marsh's test for, 179, 204 
molecular weight of, 173 
odor of, 175 
quantitative determination of, 

650 
red native sulphide, 173 
reduction of arsenic to arsenows 
compounds, 175, 183, 185 



Arsenic, Eeinsch's test for, 178 

sources of, 173 

sulphides, 173, 183, 190, et seq. 
192 

trioxide, 173 

white, 173 

acid solution of, 174 
alkaline solution of, 174 

yellow native sulphide, 173 
Arsenical ores, 173 

poisoning, antidote, 183 

sulphur, 183 
Arsenide of cobalt, 141 

hydrogen, 180 
Arsenio-sulphide, cobalt, 141 

iron, 173 

nickel, 143 
Arsenite, cupric, 184, 208 

potassium, ]74 

silver, 184 

sodium, 174, 175 
Arsenites, 174 

Arseniuretted hydrogen, 180, 204 
Arsines, 509 
Arsenous acid, 173, 174 

ar.hydride, 173, 174, 178 

chloride, 179 

iodide, 173 

oxide, 173 

sulphide, 183, 192, 202, et seq. 
Art of chemistry, 18 
Artemisia absinthium, 496 

maritima, 471 

pancifiora, 504 
Artificial" alkaloids, 511-513 
Asafetida, 479 
Asafoetida, 479 
Asagrxa officinalis, 540 
Asbestos, 337 

platinized, 292 
Ascidia, 496 
Asclepedin, 507 
AscJepias tuberosa, 507 
Aselline, 443 
Aseptol, 429 
Ash, 107 

black-, 89 

bone-, 117 

soda-, 90 
Asparagin, 332, 461 
Aspartate, ammonium, 332 
Asphalte, 478 
Aspidinol, 444 
Aspidium, 444 
Aspidospermine, 527 
Aspirin, 458 

Asymmetric carbon atoms, 306 
-ate, meaning of, 77, 81 
Atees, 527 



INDEX, 



693 



Ateesine, 527 

Atis, 527 

Atmosphere, aqueous vapor in, 32 

carbonic anhydride in, 32, 298 

composition of, 32 

minor constituents, 32 

nitrogen in, 31, 32 

oxygen in, 24, 32 

ozone in, 261 
Atmospheric pressure, measure- 
ment of, 44 
Atomic heat, 58 

proportions, 53, 210 

symbols, 69 

theory, 52 

weights, 52, 55, 682 

as indicated by densities of 
gases and vapors, 56, 
et seq. 
specific heats, 58 
Atomicity, 63 
Atoms, 52, et seq. 

conception of, 52 

linkage, 375, 410 

nascent, 69 

quantivalence of, 63 
Atropa belladonna, 527 
Atropia, 527 
Atropina, 527 
Atropinse sulphas, 529 
Atropine, 511, 527, 541 

acid malate, 527 

sulphate, 527 

synthesis, 528 
Attar of rose, 469 
Aurantii amari cortex, 507 
Auri et sodii chloridum, 198 
Auric chloride, 198 

solution of, 198 
Auripigmentum, 173 
Aurous-auric sulphide, 198 
Aurum, 38 

Australian kino, 342 
Avignon grains, 551 
Avogadro's Hypothesis, 53 
Azadirach, Indian, 507 
Asadirachta Indica, 507 
Azobenzene, 408 
Azoimide, 510 
Azoxybenzene, 408 

Babool, 343 

Bacillus acidi lactici, 331 

Bacteria, 421 

Bacterium mycodermi, 281 

Bael fruit, 495 

mucilage, 495 
Bahia powder, 412 
Bakas, 540 



Baking-powder, 485 

Balance, 598 

Balloons, coal-gas for, 29 

hydrogen for, 29 
Balm-of-Gilead fir, 478 
Balsam, Canada, 415, 478 

copaiba, 477 

Gurjun, 477 

of Peru, 323, 460, 474 

of tolu, 323, 460, 474 
Balsams, 474 
Balsamum peruvianum, 460, 474 

tolutanum, 460, 474 
Baphia nitida, 552 
Baptin, 529 
Baptisia tinctoria, 529 
Baptisin, 529 
Baptitoxine, 529 
Bar (wrought) iron, 150 
Barbados aloes, 413 
Barbaloin, 413 
Baric chloride, nitrate, etc., see 

Barium. 
Barium, 109 

analytical reactions of, 110 

antidotes to, 111 

arsenate, 185 

dichromate, 169 

carbonate, 110 
native, 109 

chloride, 109 

test solution, 109 

chromate, 110, 169 

derivation of word, 38 

detection of, in presence of 
strontium, calcium, and mag- 
nesium, 128 

dioxide, 109 

flame, 110 

hydrogen phosphate, 110, 317 

hydroxide, 109 

hypophosphite, 329 

nitrate, 109 

oxalate, 110 ■ 

oxide, 109 

persulphate, 295 

phenolsulphonate, 435 

phosphate, 317 

quantitative determination of, 
645 

salts, antidotes to, 111 

strontium and calcium, separa- 
tion of, from magnesium, 128 

sulphate, 109, 110.^290, 293 

sulphide. 109 

sulphite. 290 

tungstate. 555 
Barley, luiskod, 488 

pearl, 488 



694 



IXDEX. 



Barley starch, 488, 490 (fig.) 

sugar, 485 
Barometer, 45 
Barwood. 470, 552 
Baryta, 109 

-water. 109 
Basalt, 146 
Bases, acidity of. QQ 

classes of, 64 

organic, 508 

properties of, 64 
Basic character, 66 

salts, 66 
Basicity of acids, 66, 251 
Bassorfii, 121, 494 
Bastard satfrou. 553 
Bate brick, 337 
Bauxite, 146 
Bay oil, 469 

-salt, 86 
Bayberry oil. 469 
Beau, Calabar, 537 

St. Iguatius's, 523 

Touka, 461 
Beaue's ozone generator, 261 
Bearberry, 342. 498 
Beaver-tree. 507 
Bebeeru bark, 529 

wood, .529 
Beberine, 529 

sulphate, 529 
Bebirine. 529 
Beer. 422, 493 
Beeswax. 426 
Beetroot. 484 
Behenic acid, 4.55 
Belladonna, 527, 535 

Japanese, 529 
Belladonna folia, 527 

radix, 527 
Bell-metal. 193 
Bend glass tubes, to, 21 
Benne oil, 444 
Benzaconine. 527 
Beuzaldehyde, 322. 435, 456 

cyanhydrin, 497 
Benzaldehydum, 4.56 
Benzene, 322. 406 

addition compounds. 411 

di-derivatives of. 410 

formation from acetylene, 396 

formula for, 410 

hexachloridc, 410 

meta-disulphonic acid. 436 

mono-derivatives of. 410 

ring, 409. 436 

series of hydrocarbons. 406 
constitution of. 409 

sulphonic acid, 428, 432 



Benzene, tri-derivatives of, 410 
Benziu. 387. 406 
Benzine Collas, 467 
Benzinum, 387 

jjurificatum, 387 
Benzoate, ammonium, 98, 322 

ferric, 322 

lithium, 323 

sodium, .322 
Benzoates, 321 

tests for, 323 
Benzodichloride. 324 
Benzoic acid, 322, 435, 456 
Benzoin, 322, 325, 474 

Siam, 459 
Benzoinated lard, 442 
Benzoinum, 321, 474 
Benzole, 406 
Benzolin, 387 
B'enzosulphinide, 428 
Beuzosuljyhinidinn, 428 
Benzotrichloride, 409 
Benzoyl chloride, 456 

ecgonine, 532 

methyl ecgonine, 532 

pseudo-tropeine, 532 

sulnhonic imide, 429 
Benzyfalcohol, 435, 460 

benzoate, 321. 460 

chloride, 409 

cinnamate. 460 
Benzylidene chloride, 409 
Berbamine. 530 
Berberine, 530 

acid sulphate, 530 

periodide. 530 
Berheris vulgaris, 530 
Bergamot juice, 308 

oil, 466 
Bergapten. 467 
Berlin blue, 554 

red. 5.52 
Berzelius's tube. 177 
Beryllium, see Glnciuum. 
Bessemer steel. 150 
Betaine. 511 
Betanaphthol. 411 
Betel 3i3 
\ Bettendortf" s test for arsenic, 182 
' Betvla lenta. 458 
Bhang. 475 
Bi-, the prefix, 77 
Bibasic, see Dibasic. 
Biberine, 529 
Bibiru bark. 529 
Biborate sodium. 318 
Bibulous paper. 115 
I Bicarbonate ammonium, 96 

calcium. .301 



INDEX. 



695 



Bicarbonate, potassium, 7G 

sodium, 87 

chemically pure, 614 
lozenges, 89 
Bichloride, mercury, 214 
Bikh, 527 
Bile, 549 

detection of, in urine, 577 

tests for presence of, 550 
Biliary calculi, 591 
Bimeconate, morphine, 514 
Bioses, 481, 484 
Birch oil. 458, 466 
Bish, 527 
Bismuth, 227 

analytical reactions of, 231 

and ammonium citrate, 230 

and potassium iodide, 570 

bromide, 229 

carbonate, 230 

citrate, 230 

derivation of word, 38 

glance, 227 

hydroxide, 231 

hydroxynitrate, 229 

iodide, 229 

nitrate, 228 

ochre, 227 

oxide, 227, 229 

oxynitrate, 228, 555 

oxysalts, 228 

quantitative determination of, 
654 
of bismuth in, 763 

salts, composition of, 229, 230 
test for calcium phosphate 
in, 231 

snbcarbonate or oxycarbonate, 
228, 230 

subgallate, 230 

subnitrate, 228 

subsalicylate, 230 

sulphate, 229 

sulphide, 227, 231 
Bismuthi citras, 230 

et ammonii citras, 230 

snbcarhonas, 230 

subgallas, 231 

suhnitras, 228 

subsalicylas, 230 
Bismuthyl,"230 
Bisulphate, quinine, 510 
Bisulphide, carbon, 302 
Bisulphite of lime, 289 

sodium, 289 
Bitartrate. potassium, 83 
Bitter almonds, oil of, 322, 435,456, 
466, 497 
water of, 268 



Bitter almonds, cassava, 488 

-sweet, 538 

wine of iron, 161 
Bittern, 255 
Bituminous coal, 193 
Biuret reaction, 576 
Bivalence, 63 
Bivalent radicals, 63 
Bixa orellanay 552 
Bixin, 552 
Black alder bark, 412 

-antimony, 186 

-ash, 89 

-band ironstone, 149 

boue-, 297, 555 

cherry bark, 498 

cohosh, 507 

coloring matters, 555 

" drop," 282 

dves, 555 

flux, 175 

haw, 507 

hellebore, 501 

ink, 165, 505 

ivory, 555 

lamp-, 297, 555 

-lead, 36, 298, 555 

mustard, 427 

oxide, copper, 206 
iron, 150 
manganese, 138 
mercury, 217 

pepper, 538 

platinum, 200 

snake-root, 507 

sulphur, 285 
Blackberry, high, 343 
Bladder, green, 554 
Blonc de Perle, 229 
Blast furnace, 149 
Blaud's pill, 153 
Bleaching by chlorine, 35, 277 

-liquor, 120 

-powder, 119 

salts, 277 
Blende, 131 
Block tin, 193 
Blood, 544 

absorption spectrum, 559 

composition of, 544 

corpuscles, 544 

detection of, in urine, 577. 587 

hydrocyanic acid in the, 269 

plasma, 544 

root, 538 
Blowpipe, analysis, 355, 35(5 

-flame, 136 
Blue cohosh, 507 

t coh>ring-matters, 553 



696 



INDEX. 



Blue copperas, 152 

flag, 507 . 

gum tree, 342 

indigo, 553 

litmus paper, 99 

ointment, 210 

Prussian, 165, 265, 269, 326, 554 

stone, 206 

Turnbull's, 164, 327, 554 

vitriol, 152, 206 
"Boiled oil," 443 
Boiling-point, definition of, 594 

determination of, 595 
Boiling-points of various substances. 

594 
Boldine, 467 
Boldo oil, 467 
Bonds, 375 
Bonduc seeds, 507 
BonduceUas Semina, 507 
Bone-ash, 117, 315 

-black, 297, 555 

-earth, 117, 312 

-oil, 511 
Bones, composition of, 117, 312 
Boneset, 507 
Boracic acid, 318 
Borate, glyceryl, 320 

manganese, 140 
Borates, 318 

analytical reactions of, 320 
Borax, 318 

bead, 139 

honey, 319 
■ volumetric determination of, 
617 
Bordeaux turpentine, 415 
Boric acid, 318 

as an antiseptic, 319, 544 

anhydride, 318 
Borneene, 472 
Borneo camphor, 472 
Borneol, 472 
Boron, 318 

chloride, 318 
derivation of word, 38 
fluoride, 318 
Borotartrate, potassium, 319 
Bos taurus,54i9 
BosicelUa, 479 
Botany Bay kino, 342 
Bourdon barometer, 45 
Boyle's law, 46 
Brandy, 422 
Brass, 132 
Braashajuncea, 427 

nigra, 427 

Brazil powder, 412 

wood, 552 



Bread, 484 

aerated, 485 

alcohol in, 420 

-making, 484 
Breidin, 478 
Brezilin, 552 
Bricks. 338 
Bright' s disease, 576 
Britannia metal, 186, 193, 222 
British gum, 492 
Bromal, 453 

alcoholates, 453 

hydrate, 453 
Bromate potassium, 81 
Bromates, 257, 280 

detection of, in bromides, 257 
Bromic acid, 81, 280 
Bromide, ammonium, 98, 256 

antimony, 186 

bismuth,"^ 229 

cadmium, 232 

ethyl, 398 

ferrous, 155 

hydrogen, 256 

lithium, 104 

phosphorus, 256, 313 

potassium, 81, 257 

volumetric determination 
of, 626 

silver, 237, 257 

sodium, 91. 257 

starch, 258' 

sulphur, 287 

zinc, 134 
Bromides, 255 

analytical reactions of, 257 

detection of bromates in, 257 

quantitative analysis of, 660 

separation of, from chlorides 
and iodides, 261 
Bromine, 255 

analytical separation of, 258 

chloride, 258 

derivation of word, 38 

its aualogv to chlorine and io- 
dine, 264 

solution of, 257 

specific gravity, 264 

test solution, 257 

volumetric determination of 
free, 770 

water, 257 
Bromoform, 400 
Bromoformum, 400 
Bromum, 255 
Bronze, 193 

aluminium, 146 

leaf, 196 
Bronzing-powder, 196 



INDEX. 



B97 



Broom-tops, 539 

Brown coloriug-matters, 555 

hsematite, 149 

resiu, 474 

suo;ar, 484 
Brucia, 525 
Brucine, 525 

distiuction from morphine, 525 
Brunswick green, 184 
Bryoidin, 478 
Buchu, 467, 507 

oil, 467 
Buckthorn green, 554 

-juice, 498 ^ 
"Bumping," 267 
Buusen gas-burners, 29 
Burdock, 507 
Burgundy pitch, 476 
Burners, gas-, 28 
Burnett's disinfecting fluid, 133 
Burnt ochre, 552 

sugar, 485, 555 

umber, 555 
Butane, 386 

synthesis of, 383 
Biitea frondosa, 342 
Butter, 443, 545 

of antimony, 187 

of cacao, 442 

of cocoa, 442 

of kokum, 443 

of orris, 469 
Butyl alcohol, 347, 424 

-chloral, 453 

hydrate, 453 
Butylene, 392 
Butyrate, cupric, 348 

ethyl, 405 
Butyrates, 347 
Butyric acid, 347, 453 

aldehyde, 467 
Butyrone, 464 
Buxine, 529 
Biixus sempervirens, 529 
By-products, 213 

Cabbage-eose petals, 552 
Cacao-butter, 442 
Cacodyl oxide, 323 
Cacodylate ferric 323 

sodium, 323 
Cacodylic acid, 323 
Cadaverine, 511 
Cade, oil, 478 

Cadet's fuming liquid, 323 
Cadinene, 415, 469 
Cadmium, 232 

analytical reactions of, 232 

bromide, 232 



Gadinium:, chloride, 232 

derivation of word, 38 

hydroxide, 233 

iodide, 232 

oxide, 233 

sulphide, 232, 233 
Csesalpinia bonducella, 507 

brasiliensis, 552 
Caesium, 682 
Caffeina, 530 

citrata, 531 

effervescens, 531 
Cafi'eine, 530 : ;■ 

citrate, 531 

physiological action of, 531 

relation to the bromine, 531 

synthetic, 539 , 

Cajuputene, 467 
Cajuput oil, 467 
Cajuputol, 467 
Cajug coal, 193 
Calabar bean, 537 
Calivniiina prasparata, 134 
Calamine, 131 

prepared, 134 
Calamus draco, 475 
Calcareous precipitated sulphur, 286 
Calcic sulphate, phosphate, etc., see 

Calcium. 
Calcii bromidum, 113 

carbonas prsecipilatus, 114 

chloridum, 113 

hypophospJiis, 118, 329 

phosphas prxcipitatus, 117 

sulphas exsiccatus, 112 
Calcined magnesia, 126 
Calcis, liquor, 114 

syrupus, 114 
Calcium, 112 

acetate, 281 

analytical reactions of, 121 

arsenate, 185 

bicarbonate. 301 

bisulphite, 289 

bromide, 113 

carbide, 122, 395 

carbonate, 112, 115, 298 
precipitated, 114 

chloride, 112 

removal of iron from, 113 

citrate, 308, 310 

derivation of word, 38 

flame, 122 

fluoride, 112, 327 
in bones, 118 

gummate, 121 

hydroxide, 114 

hvpoclUorite, 121 

hVpophosphite, 118, 329 



698 



INDEX. 



Calcium, in presence of barium, 
strontium, and magnesium, 
detection of, 121 

lactate, 331 

lactophosphate, 331 

malate, 332 

mecouate, 332 

metagummate, 494 

oxalate, 303 

oxide, 113 

phosphate, 112, 117, 312 
acid, 315 

polysulphide, 286 

quantitative determination of 
646 

santonate, 504 

silicate,. 112, 337 

strontium, and barium, separa- 
tion from magnesium, 128 

sulphate, 112, 122, 290 

in precipitated sulphur, 324 
test solution, 128 

sulphide, 120 

sulphite, 289 

tartrate, 305, 307 

thiosulphate, 286 
Calc-spar, 112 
Calculi, urinary, 572 

examination of, 589 
Calendula, 507 
Calendulin, 507 
Caliche, 271 
Calomel, 215, 220, 255 

test for corrosive sublimate in, 
215 
Calotropis, 507 

gigantea, 507 

procera, 507 
Calumba, 530 

root, 530 
Calx, 113 

chlorinata, 119, 277 

sulphurata, 120 
Cambogia, 479 
Camphene, 415 
Camphor Borneo, 472 

cerate, 473 

Dutch, 472 

Formosa, 472 

hydrous, 472 

laurel, 472 

liniment, 473 

monobromated, 472 

oil, 472 

spirit, 473 

water, 472 
Camphora, 472 

morobromata, 472 
Camphoric acid, 473 



Camphoronic acid, 473 
Camphors, 472 
Cam-wood, 552 
Canada balsam, 415, 478 
Canadian hemp, 507 

moonseed, 530 

turpentine, 415 
Candle-flame, composition of, 28 
Canellse cortex, 507 
Cane-sugar, 482 
Cannabene, 475 
Cannabin, 474 
Cannabinine, 475 
Cannabis indica, 467, 474 
oil of, 474 

sativa, 475 
Cantharidic acid, 473 
Cantharidiu, 473 
Cantharis, 473 
Caoutchin, 471 
Caoutchouc, 471 
Capacity, unit of, 18 
Capillary, 593 
Capric acid, 455 
Caproate, glyceryl, 442 
Caproic acid, 442, 455 
Caprylate, glyceryl, 442 
Caprylic acid, 442, 455 
Capsaicin, 531 
Capsicin, 477 
Capsicine, 531 

hydrochloride, 531 

sulphate, 531 
Capsicum, 477. 531 

fruit, 477, 531 
resin of, 475 

oil, 443 
Caramel, 485, 555 
Caraway-oil, 467 
Carats fine, 197 
Carbamate, ammonium, 96 

ethyl, 455 
Carbamic acid, 455 
Carbamide, 455 
Carbamines, 447 
Carbazotic acid, 435, 552 
Carbide, calcium, 121, 395 
Carbinol, 418 

methyl, 419 
Carbinols, 417 
Carbo anhnalis, 297 

purificatus, 297 

ligni, 297 
Carbohydrates, 480 
Carbolates, 434 
Carbolic acid, 432 

antidotes to, 434 
Carbon, 36, 297 

bisulphide, 302 



INDEX, 



699 



Carbon, combustion of, 36 

compounds, chemistry of, 368 
derivation of word, 38 
disulphide, 302 
monosulphide, 302 
monoxide, see Carbonic oxide, 
nucleus, 377 
oxychloride, 399 
quantitative determination of, 
in oi'ganic compounds, 670, 
et seq. 
silicide, 339 
tetrachloride, 396 
Carbonate, ammonium, 96 
solution of, 97 
barium, 110 
bismuth, 230 

calcium, 112, 114, 298, 300 
ferrous, saccharated, 152 
hydrogen, 298 
iron, 152 
lithium, 103 

magnesium, 123, 124, 126, 301 
potassium, 72 

acid, 76 
sodium, 86, 89 
acid, 88 

chemically pure, 614 
manufacture of, 89 
strontium, 112 
zinc, 131, 134 
Carbonates, 297 

analytical reactions of, 300 
detection of, in presence of sul- 
phites or thiosulphates, 300 
gravimetric determination of, 

665 
volumetric determination of 
alkaline, 618 
Carhonei Disulphidum, 302 
Carbonic acid, 77, 297, 455 
gas, 36 
anhydride, 36, 298 
generation of, 76 

solubility of, in water, 299 
specific gravity of, 300 
oxide, 36, 299, 304, 326 
Carbonization, 107 
Carbon vl, 417 

chloride, 399 
Carborundum, 339 
Carboxyl group, 384, 417 
Carburetted hydrogen, light, 385 

heavy, 392 
Cardamom -oil, 467 
greater, 468 
lesser, 467 
Cardamomum, 467 
Carica papaya, 531, 549 



Carmine, 323 

Carminic acid, 323 

Carnauba wax, 426, 453 

Carnallite, 71 

Carnine, 511 

Carolina yellow jasmine, 535 

Caro's acid, 296 

Carpaine, 531 

Carrageen moss, 494 

Carrotin, 552 

Carthamin, 553 

Carthamus tinctorious, 553 

Carum, 467 

ajowan, 466 

capticum, 470 
Carvacrol, 471 
Carvene, 467 
Carvol, 467 
Carvone, 467, 469 
Caryophyllene, 415, 467 
Cascara sagrada, 412 
Cascarilla, 467 

-oil, 467 
Cascarillin, 507 
Casein, 544 

vegetable, 546 
Casein ogen, 544 
Cassava, bitter, 488 
Cassia fistida, 484 

-oil, 467 
Cassius, purple of, 199 
Cast-iron, 151 
Castile soap, 441 
Castilloa elastica, 471 
Castor, 475 

fiber, 475 

oil, 444 
Castorin, 475 
Catechin, 342 
Catechu, 342, 555 
Catechuic acid, 342 
Cathartic acid, 498 
Cathartogenic acid, 498 
Cathode, 68 

Caidox>hillmn Thalidroides, 507 
Caustic, 235 

lime, 113 

lunar, 235 

potash, 72 

soda, 86 
Cavenne pepper, 531 
Cedra-oil, 466 
Celandine, 538 
Celcstine, 111 
Cellulin, 495 
Celluloid, 496 
Cellulose, 495 

of starch, 489 
Cements, 338 



700 



IXDEX. 



Centesimal composition. 60 
Ceutiare, 41 

Centigrade thermometer, 44 
Centigramme, 41 
Centimetre, 41 
Cephaeline, 532, 534 
Cephaelis ipecacuanha, 532, 5S4 
Cera alba, 426 
flava, 426 
Cerasin, 494 
Cerate Goulard's, 224 
Cerates, 592 
Ceratum camphorse, 473 

cantharidis, 473 
plumbi subacetatis, 224 
Ceresine, 426 
Cerii oxalas, 172 
Cerite, 171 
Cerium, 171 

derivation of word, 33 

oxalate, 172 

potassium sulphate, 172 
Ceroleine, 426 
Cerotic acid, 338. 453, 455 
Ceryl alcohol. 426 

cerotate, 426 
Cetaceum, 425 
Cetine. 426 
Cetraria islandica, 491 
Cetraric acid. 323 
Cetyl alcohol. 425 

hydroxide, 425 

palmitate. 426 
Cevadilla. 540 
Cevadilline, 540 
Cevadine. 536, 540 
Cevlon '■ moss."" 494 
Chalcedonv. 337 
Chalk, 112, 555 

French, 555 

prepared, 117 

stones, .591 
Chalybeate water, 149 
Chamber crystals. 291 

process for sulphuric acid man- 
ufacture. 291 
Chameleon mineral, 139 
Chamomile flowers, 466 

oil, 466 
Char, 107 
Charas. 475 
Charcoal, 36, 297 

animal, 297 

decoloring power of, 298 
purified, 297 

wood, 293 ^ 

Charles"s law. 46 
Charta sinapis, 427 
Chartreuse, 422 



I Chaulmoogra oil, 444 
I Chaulmugra, 444 
I Chavica officinariim, 538 
Chavicic acid, 538 
Chavicol, 343 
Chebulic myrobalaus, 340 
Cheese, 545 

poison, 511. 571 
Chelerythrine, 533 
CheUdonhon, 53S 

Chemical action, illustration of by 
symbols, 61, 72 
aflinity, 50 
changes, 49 

characteristics of, 49 
disappearance of properties 

during, 49 i 

equations and diagrams f 

representing, 72 ^ 

heat given out or absorbed 

during, 50 
take place between definite 
quantities of substances, 
51 
combination laws of, 51 
by volume, laws of, 51 
by weight, laws of, 51 
different from mechanical 
mixture, 37, 50 
compound, 25, 49 

definition of, 50 
diagrams, 62, 73 
equations. 61, 72 
formulae 59 
notation. 58. et fieq. 
philosophy, principles of, 49, 

et seq. 
reagents, xv. 
symbols. 58 
toxicology. 559 
Chemicals, lists of. xvi. 
Cliemistry, art of. 13 
definition of. 49 
derivation of the word, 18 
object of. 17 

of carbon compounds, 368 
organic, 368 
science of, 13 
Chemists, pharmaceutical, 19 
Cherry-laurel water, 263, 487 
sugar in. 482 
-tree gum. 494 
wild black. 498 
Chestnut-brown, 555 
Chian turpentine. 415 
Chicory. 491 
Chili saltpetre, 271 

nitre, 271 
ChimaphUa, 498 



INDEX^ 



701 



Chimaphila umbellata, 498 
China clay, 338 
Chinese green, 548 

moss, 494 

red, 552 

was, 426 

white, 555 

yellow, 551 
Chinoidine, 522 
Chinoliue, 511 
Chirata, 335 
Chiratin, 335 
Chirotogenin, 335 
Chiretta, 335 
Chloral, 449 

alcoholates, 450, 552 

butyl, 453 

croton, 453 

hydrated, 450 

determination of, 451 
Chloralformamide, 452 
Chloralformamidum, 452 
Chloralose, 452 
Chloralum liydratum, 450 
Chlorate, calcium, 278 

potassium, 277 

preparation of oxygen 
from, 20 

sodium, 279 
Chlorates, 277 

analytical reactions of, 279 
Chloraurate, sodium, 198 
Chlorauric acid, 198 
Chloretone, 424 
Chloric acid, 120, 277 
Chloride, acetyl, 282 

aluminium, 147 

ammonium, 93 

antimony, 186 

arsenic, 179 

auric, 198 

barium, 109 

boron 318 

bromine, 258 

calcium, 112 

chromic, 166 

chromyl, 169 

cobalt, 142 

detection of, in presence of bro- 
mide or iodide, 262 

ethyl, 398 

ethylene, 392, 393 

ferric, 155 

ferrous, 154, 156 

gold, 198, 570 

iridium, 570 

iron, 154, 156, ct scq. 

lead, 225 

lime, 119 



Chloride, magnesium, 123 
manganese, 138 
mercuri-ammonium, 218 
. mercuric, 213 

mercuros-ammouium, 220 
mercurous, 215, 219 
methyl, 398 
nickel, 143 
nitrosyl, 273 
palladium, 570 
phosphorus, 283, 313 
platinic, 200 
platinum and am- ^ 

monium | See 
and lithium ^ chloro- 
and potassium I platinates 
and sodium J 
potassium, 71 
silicon, 339 
silver, 234, 255 
sodium, 86, 252 
sulphur, 287 
stannic, 194 
stannous, 194 

solution of, 194 
zinc, 133 
Chlorides, 252 

analytical reactions of, 255 
detection of, in presence of 

bromides and iodides, 262 
determination of, 659 
quantity present in urine, 580 
separation of, from bromides 
and iodides, 261 
Chlorinated lime, 119, 278 

volumetric determination 
of, 636 
potash, 377 
soda, solution of, 91, 277 

volumetric determination 
of, 636 
Chlorination, 395 
Chlorine, 33, 252, 254 
acids, 280 

as a disinfectant, 35 
bleaching by, 35 
collection of, 34 
derivation of word, 38 
hydrate, 254 
its analogy to bromine and 

iodine, 264 
liquid, 254 
peroxide, 279 
preparation of, 34 
properties of, 34 
relative Aveight of. 36 
solubility in Avatcr, 34 
solution of, 254 
specific gravity, 264 



702 



INDEX. 



CMorine, substitution, 395 

the active ageut iu bleaching- 
powder, 120 

volumetric determiuatiou of, 
t)3o 

-water, 254 
Chlorochromic anhydride, 169, 263 
Chloroform, 396, 399 

water, 400 
Chloroformum, 399 
Chlorophyll, 299, 554, 592 
Chloroplatinate, ammonium,102, 201 

lithium, 104 

potassium, 83, 201 

sodium, 201 
Chloroplatinic acid, 199 
Chocolate, 442 
Cholalic acid, 550 
Cholesterin, 440, 591 
Cholic acid, 550 
Choline, 511, 550 
Chondrin, 547 

Chondrodenclron tomentosum, 529 
Chondrus, 494 
Christmas rose, 501 
Chromate, barium, 110 

conversion of a, into a chromic 
salt, 167 

lead, 167, 169, 226 

mercurous, 221 

potassium, 167 

silver, 238 

strontium. 112 
Chromates, 166 

analytical reactions of, 168 
Chrome-alum, 147, 168 

-ironstone, 166 

-orange, 226 

-red, 552 

-yellow, 226, 551 
Chromes, 226 
Chromic acid, 167, 168 

anhydriue, 166, 168 

hydroxide, 169 

oxide, 166, 555 
hydrous, 554 

salts, 166 

analytical reactions of, 169 

sulphate, 166, 168 
Chromii Trioxidtim, 168 
Chromite, 166 
Chromium, 166 

analytical reactions of, 169, 170 

chloride, 166 

derivation of word, 38 

oxides, 166 

oxy hydroxides, 170 

separation of, from aluminium 
and iron, 170, 171 



r 



Chromium, sulphate, 166, 168 

trioxide, 168 
Chromogeus in urine, 580 
Chromous salts, 366 
Chromule, 554 
Chromyl chloride, 169 
Chrysammic acid, 413 
Chrysarobin, 412 
Chrysarobinnm, 413 
Chrysatropic acid, 529 
Chrysophan, 412 
Chrysophanic acid, 412 
Churning, 545 
Churras, 475 
Chymosin, 544 
Cicuta virosa, 468 
Cicutine, 533 
Cider, 422 
Cimifnga, 507 

r ace m OS a, 507 
Cimicifugin, 507 
Ciuchamidine, 523 
Cinchona, 518 

alkaloids, 518 

bark, 518 

rubra, 518 
Cinchonicine, 523 
Cinchonidinse sidphas, 522 
Cinchonidine, 521 

hydriodide, 522 

sulphate, 522 

tartrate, 522 
Chichoninse sidphas, 522 
Cinchoniue, 522 

hydriodide, 522 

sulphate, 522 

tartrate, 522 
aneol, 467, 468 
Cinnabar, 209, 552 
Cinnaldehydum, 467 
Cinnamaldehyde, 460, 467 
Cinnamein, 460 
Cinnamene, 460 
Cinnamic acid, 323, 461 

aldehyde, 460, 467 

series of acids, 460 
Cinnamol, 460 
Cinnamomuin camphora, 472 

oliveri, 470 
Cinnamon-oil, 467 
Cinnamyl alcohol, 460 

cinnamate, 460 
Cissampelos Pareira, 529 
Cissampeliue, 529 
Citral, 467 
Citrate, ammonium, 98 

bismuth, 230 

ammonium, 160, 230 

caflfeine, 531 



INDEX, 



703 



Citrate, calcium, 309, 310 
ferric, 161 
ferrous, 161 
iron, 161 

and ammonium, 159, 311 
and quinine, 159, 160, 519 
lithium, 104 
magnesium, 126 
nicotine, 536 
potassium, 77 

volumetric determination 
of, 619 
silver, 310 
sodio-ferrous, 161 
strychnine, 524 
Citrates, 308 

analytical reactions of, 310 
Citreues, 415 
Citric acid, 308, 462 

action of heat on, 309 
volumetric determination 
of, 623 
fermentation, 309 
Citromyces glaber, 309 
Pfefferianus, 309 
Citron-oil, 467 
Citronella-oil, 468 
Citronellal, 467, 471 
Citronellol, 469 
Citrus, 466 

aurantium, 467 
bergamia, 466 
limetta 466 
medica, 466 
Classification, 108, 129, 242 
Clausius's theory, 30 
Claviceps purpurea, 475 
Clay, 146, 337 
China, 338 
ironstone, 149 
Cloves, oil of, 467 
Club-moss, 444 

Coal, anthracite and other kinds, 
193 
-brasses, 149 
-gas, 297, 392, 435 

for balloons, 29 
products of, 435, 555 
-tar colors, 555 
Cobalt. 141 

analytical reactions of, 142 

and sodium nitrite, 85 

arsenide, 141 

blue, 553 

derivation of word, 38 

-glance, 141 

oxide, 141, 553 

separation of, from nickel, 142 

sulphate, 142 



Cobalt, sulphide, 142 
Cobaltic ultramarine, 553 
Cobalticyanide potassium, 142 
Cobaltic nitrite potassium, 85, 142 

sodium, 85 
Coca leaves, 532 
Cocaidine, 532 
Cocahia, 532 

Cocamse hydrocMoridum, 532 
Cocaine, 532 

hydrochloride, 532 
Cocaines, 532 
Cocamine, 532 
Coccerin, 329 
Cocculus i7idicus, 502 
Cocais, 323, 553 

cacti, 323 

ilicis, 189 
Cochineal, 323, 552 
Cocoa, 442, 539 

nibs, 442 

nut, 442 
oil, 442 
Cocos nucifera, 442 
Codamine, 517 
Codeia, 516 
Codeina, 516 
Codeinse phosphas, 516 

sulphas, 516 
Codeine, 516, 541 

phosphate, 516 

sulphate, 516 
Cod-liver, 443 
Coffee, 530 
Cohosh, black, 507 

blue, 507 
Coin, gold, 197 
Coinage, copper, 602 

gold, 602 

silver, 234, 602 
Coke, 36, 297 
Colchiceine, 533 
Colchici cormus, 533 

semen, 533 
Colchicina, 533 
Colchicine, 533, 541 
ColcMcnm aiitumnale, 533 
Colcothar, 158 
Collagen, 547 

hydrate of, 547 
Collagens, 547 
Collection of gases, 20, 21 
Collidine, 512 
Collin, 681 
Collodion, 495 

cantharidal, 496 

flexible, 496 
CoUodium, 495 

caniharidHm, 496 



704, 



INDEX. 



CoUodium, flexile, 496 
Colloids, 543, 6bl 
Colocynthis, 499 
Colocynthiu, 499 
Colopheue, 416 
Colopholic acid, 474 
Colophonic acid, 474 

hydrate, 474 
Colophonine, 474 
Colophony, 415, 474 
Coloring matters, 551 
Colorless indigo, 553 
Combination, chemical, by weight, 
50, 51 

by volume, 51 
Combining capacity, 63 

proportions, 51, 56, et seq. 
Combustible, 28 
Combustion, 28 

analysis for carbon and hydro- 
gen, 671, et seq. 
for nitrogen, 673, 674 

relation of oxygen to, 24 

spontaneous, 163 

supporters of, 28 
Commiphora myrrlia, 479 
Composition of atmosphere, 32 

bismuth salts, 229 

centesimal, 60 

calculation of empirical 

formula from, 60 
calculation of, from form- 
ula, 61 

of oils and fats, 439 

organic compounds, 370 

percent., 61 
Compound ether, 401 
Compounds, 50 

chemical, 37 

definition of, 50 
different from mechanical 
mixtures, 37, 50 

of the elements, 70 
Concentrated volatile oils, 465 
Concentration, 251, 252 

state of, 251 
Conchinine, 521 

Concrete oil of mangosteen, 443 
Condensation, 130 
Condenser, 130 
Condensing-tub, 130 

worm, 130 
Confections, 484, 592 
Conhydrine, 533 
Conia, 533 
Conicine, 533 
Coniine, 511, 533 

salts of, 533 

synthetic, 533 



Conium, 533 

maculattim, 533 
Conquinine, 521 
Constant proportions, law of, 51 
Constant white, 555 
Constitution of alkaloids, 508 

benzene series, 409 

bleaching powder, 120 

cinchona alkaloids, 523 

morphine, 517 

organic compounds, 374, 376, 
et seq. 

salts, 65, 251 

uric acid, 346, 539 
Constitutional formulae, 375 
Construction of formulae, 59 
Contact process for sulphuric acid 

manufacture, 291 
Convolvulin, 501 
Convolvulus scammonia, 505 
Conylia, 533 
Copaiba, 447 

oil, 468 : 

Copaivaol, 447 
Copaivic acid, 447 
Copal, 475 

Copernicia cerifera, 426, 453 
Copper, 205 

acetate, 184 

acetylide, 395 

ammonium sulphate, 207 

aiialytical reactions of, 207 

antidotes to, 208 

arsenate, 184 

arsenite, 184, 208 

black oxide, 206 

blue, 553 

carbonate, 554 

coinage, 602 

cuprous and cupric salts, 206 

derivation of word, 38 

detection of arsenic in, 179 

ferrocyanide, 208 

flame, 208 

hydride, 330 

hydroxide, 207, 208 

hydroxycarbonate, 205 

in organic mixtures, detection 
of, 561, 563 

iodide, 206, 208, 261 

melting-point of, 597 

nitrate, 206 

oxides, 206, 208 

oxyacetate, 206 

pyrites, 205 . 

quantitative determination of. 
652 

recovery of, from solutions, 207 

sulphate, 206 



i 



INDEX. 



7Q5 



Copper sulphate, anhydrous, 206 

sulphide, 206, 287 

test for mercury compounds, 
217 

-zinc couple, 661 
Copperas, blue, 152 

green, 152 
Coptis-root, 530 
Coptis Teeta, 530 
Coriander-oil, 468 
Coriandrol, 468 
Cork, specific gravity of, 604 

-borers, 20 
Cornutine, 476 

Correction of the volume of a gas 
for pressure, 47, 604 

for temperature. 47, 605 
Corrosive sublimate, 214, 215 
antidote to, 221 
test for, in calomel, 215 
Corundum, 146 
Corydaline, 534 
Corydalis cava, 534 
Corypha cerifera, 426 
Coscmium fenestratum, 530 
Cotarnine, 499 
Coto-bark, 499 

false, 499 
Cotoin, 499 
Cotton-root bark, 507 

-seed oil in olive oil, 435 

cake, 511 

-wool, 495 
Couch-grass, 507 
Coumarin, 460 
Cowbane, 468 
Cows' milk, 545 

"Cracking" of hydrocarbons, 373 
Cramp-back, 507 
Cranesbill, 343 
Cream, 545 

of tartar, 71 84, 305 
soluble, 319 
Creatine, 510 
Creatinine, 510 
Cremnitz white, 555 
Creosol, 433 
Creosote, 433 
Creosotum, 434 
Cresol, 433, 434 
Cresotic acid, 457 
Cresylic acid, 433 
Creta prxparata, 117 
Cmmm asiaticnm, 505 
Crocetin, 551 
Crocin, 551 
Croccus (mineral), 158 

of antimony, 186 

sativus, 551 

45 



Croton chloral, 453 

hydrate, 453 

oil, 444 
Crotonic acid, 455 
Crotoneleic acid, 444 
Crotonylene, 394 
Crown glass, 338 
Crucibles, 74, 338 
Crude antimony, 186 

potashes, 71 
Crum's test for manganese, 141 
Crusocreatinine, 510 
Cryolite, 146, 360 
Cryptopine, 517 
Crystal-glass, 338 
Crystallization, water of, 90 

fractional, 82, 362 
Crystalloids, 543 
Cube sugar, 484 
Cubeb camphor, 468 ' 

oil of, 468 

oleoresin of, 477 

pepper, 538 
Cubeba, 538 
Cubebene, 468 
Cubebin, 538 
Cubic decimetre, 41 

nitre, 271 
Cuca, see Coca. 
Cuctirbita maxima, 507 

Pepo, 507 
Cudbear, 554 
Culvers root, 507 
Cumin, 468 
Cuminic acid, 468 
Cuminum cyminum, 468 
Cummin, 468 
Cupel, 659 
Cupellation, determination of silver 

by, 659 
Cuprea bark, 523 
Cupreine, 523 
Cupri sulphas, 206 
Cupric acetate, 184 

aceto-arsenite, 554 

ammonium sulphate, 207 
test solution, 184 

arsenate. 184 

arsenite, 184, 208 

butyrate, 348 

compounds, 208 

ferrocyanide, 208 

hydroxide, 207, 208 

nitrate, 206 

oxide, 206. 208, 554 

oxyacetate, 20() 

sulphate, 206 

anhydrous, 206 

sulphide, 206, 287 






706 



INDEX. 



Cupric valerate, 348 
Cupro-arsenical pigments, 184, 554 
Cuprous hydride, 330 

iodide, 206, 208, 261 

oxide, 206, 482, 576 

sulphide, 206 
Cuprum, 38 
Curacoa, 422 
Curari, 525 
Curariue, 525 
C'uciirma longa, 471, 551 
Curcumin, 551 
Curd soap, 441 
Curds, 486, 544 

and whey, 486, 544 
Curine, 525 
Currant, sugar in, 482 
Curry powder, odor and flavor of, 

471 
Cusparidine, 534 
Cusparine, 534 
Casso, 476 
Cutch, 342 
Cuttle-fish, 555 
Cyanates, 324 
Cyanic acid, 324 
Cyanide, allyl, 427 

mercuric, 266 

nickel, 144 

potassium, 266 
nickel, 144 

silver, 237, 268 
Cyanides, 265 

analytical reactions of metallic, 
268 

antidotes to, 270 

double, 269 

quantitative determination of, 
626, 660 
Cyanogen, 164, 265 

chloride, 327 

iodide, 259 
Cyanurets, see Cyanides. 
Cyder, see Cider. 
Cymene, 406, 409, 466, 468, 472 
Cymol, 466, 468 
Cypripedin, 507 
Cypripedium, 507 

pubescens, 507 
Cystin, 583 

calculus, 591 
Cytisine, 534 

Dahlia, 491 

Dalton's automatic theory, 52 
Dambose, 484 
Dandelion, 491 
Daphne guidinm 476 
laureola, 476 



Daphne mezereum, 476, 499 
Daphnetin, 499 
Daphuin, 499 
Datura fastuosa, 535 

Metel, 535 

stramonium, 535 
Daturine, 535 
Dauglish's bread, 485 
Davy safety- lamp, 29 
Deadly nightshade, 527 
Decane, 386 
Decantation, 116 
Decimal coinage, 42 
Decoctions, 592 

Decolorizing power of animal char- 
coal, 298 
Decomposition, 50 

double, 73 
Decrepitation, 355 
Decylene alcohol, 427 
Deflagrating flux, 360 
Deflagration, 80 
Deliquescence, 91 
Delphine, 534 
Delphinine, 534 
Delphinium staphysagria, 534 
Delphinoidine, 534 
Densities, relative, 47 
of gases, 48 

of liquids and of solids, 47 
Density, 47 

vapor, 48, 605 
Deodorizers, 35 
Deodorizing liquid, 133 
Deoxidation, 69 
Deposits, urinary, 582 
Derivation of names of elements, 

37, et seq. 
Desiccation, 640, 670 
Desiccators, 640 
Destructive distillation, 131, 281, 

372 
Detonation, 80 
De Valangin's solution, 174 
Dextrin, 492 
Dextrorotation, 306 
Dextrose, 482 
Dextrotartaric acid, 306 • 
Dhak tree, 342 
Dhatura, 535 
Diabetes meUitus, 580 
Diabetic urine, 577 
Diacetylmorphine, 516 
Di-acid bases, 66 
Diamide, 510 
Diagrams, chemical. 62, 72, 382, 

et seq. 
Diallyl disulphide, 427 
Dial y sate, 680 



INDEX. 



707 



Dialysis, 339, 544, 680 
Diamines, 509 
Diamond, 36, 298 
Diaphragms, 76 
Diastase, 489, 492 

action of, upon starch, 489, 492 
Diatomic alcohols, 435 
Diazobenzene, 511 
Dibasic acids, 66, 251, 461 
Dibromethane, 394 
Dichlorobenzene, 410 
Dichloromethane, 396 
Dichlorotoluene, 409 
Dichopsis gutta, All 
Dichroism, 537 
Dichromate, ammonium, 167 

potassium, 167 

standard solution of, 631 
Didymium, 172 
Dietetics, 19 
Diethyl, 386 
Diethylamine, 508 
Diethyl-ammonia, 508 

-ammonium iodide, 509 

-hydrazine, 510 

-sparteine, 539 

-sulphone-diethylmethane, 428 
-dimethylmethane, 428 
-methylethyl methane, 428 
Diethylene-diamine, 509 
Diffusate, 680 
Diffusion of gases, 30 

relative rates of, 30 
Digallic acid, 340 
Digitaligenin, 499 
Digitalin, 499 
Digitaline crystallisee, 500 
Digitalis, 499 

purpurea, 499 
Digitalose, 499 
Digitogenin, 499 
Digitonin, 499 
Digitoxigenin, 500 
Digitoxin, 499 
Digitoxose, 500 
Dihydric alcohols, 417, 435 
Dihydroxyacetic acid, 455 
Dihydroxybenzenes, 435 
Dihydroxybutyric acid, 455 
Dihydroxyl derivatives of hydro- 
carbons, 435 
Dihydroxypropionic acid, 455 
Dihydroxysuccinic acid, 462 
Dihydroxytoluene, 437 
Di-iodo-paraphenolsulphouic acid, 

429 
Di-iodo-salicylic acid, 458 
Di-ketone, 518 
Dill-oil, 466 



Dimercuri-ammonium iodide, 219 
Dimethyl, 386 

benzene, 406 

ethyl-carbinol, 425 

ketone, 464 

xanthine, 539 
Dinitrocellulin, 495 
Dioniu, 516 
Diosphenol, 467 
Diospyros embryopieris, 343 
Dioxide, barium, 109 

chlorine, 279 

hydrogen, 109 

iron, see Ferric oxide, 

lead, see Lead peroxide 

manganese, 138 

nitrogen, 271, 274, 275 

sodium, 23, 92 
Dipentene, 415 
Dipterocarpus turbinatus, All 
Disinfectant, chlorine as a, 35 
Disinfectants, 35 
Disinfecting fluid, Burnett's, 133 
green, 139 
purple, 139 

powder, 119 

solution, 120 
Distillation, 129, 373 

destructive, 131, 281, 372 

dry, 131, 372 

fractional, 362, 373, 420 
Distilled water, 131 
Disulphide, allyl propyl, 427 

carbon, 302 

diallyl, 427 
Dita, 534 
Ditaine, 534 
Ditamine, 534 
Dithionic acid, 296 
Dobereiner's lamp, 201 
Dock, 412 
Dolomite, 123 
Donovan's solution, 173 
Dorema ammoniacum, 479 
Doremus ureometer, 579 
Double chloride, aluminium and 
sodium, 146 

cyanides, 269 

decomposition, 73 

salts, 94, 146 
Doundake, 475 
Dover's powder, 534 
Dracoalban, 475 
Draeonyl, 460 
Dracoresen. 475 
Dragon's blood, 475 
Dried alum, 147 
Dropped tin. 193 
Dry distillation, 131, 372 



708 



INDEX. 



Drying apparatus, 118 
in vacuo, 118, 640 
-oils, 443 
precipitates, 118, 640 

Dryobalanops aromatica, 472 

Dryopteris fiUx-mas, 477 

Buboisia myoporoides, 535 

Duboisine, 535 

Dulcamara, 538 

Dulcamarin, 538 



Electrolytic synthesis of, paraffins 

384 
Element, definition of, 50 
Elements, 17, 18, 19, 37, 50, 682 
and their compounds, 70 
atomic weights, 682 
classification of, according 

analogy, 308 
etymology of names of, 37 



to 



(t 



Dulciu, 408 


metallic, 20 




Dulcite, 446 


non -metallic, 20 




Dulong and Petit's law, 58 


of medical or pharmaceutical 


Dutch camphor, 472 


interest, 19 




Dyeing by mordants, 148 


of pharmaceutical 


interest, 19 


D}-er's saflron, 553 


symbols of, 59, 682 




Dynamite, 438 


Elemi, 477 
Elettaria repens, 467 
Elutriation, 134 




Earth, bone-, 117, 312 


fractional, 362 




fuller's 338 


Emhelia ribes, 324 




-nut oil, 444 


robnsta, 324 




pitch, 478 


Embelic acid, 324 




Earthenware, 338 


Emerald green, 554 




Earths, alkaline, 129 


Emery, 146 




Eau de Cologne, 465 


Emetic cups, 186 




de Javelle, 91 


tartar, 188 




Ebonite, 471 


Emetine, 532, 534 




Ebullition, 267 


nitrate, 534 




Ecboliue, 475 


Emodin, 412, 500 




Ecgonine, 532 


Empirical formula, 60, 


608 


Echitamine, 534 


deduction of. 


from com- 


Echitenine, 534 


position percent., 60 


Echites scJwInris, 534 


Emplastrum hydrargyri, 


210 


Effervescing magnesium sulphate, 


plumbi, 225 




124 


Emulsin, 497 




powder, compound, 306 


Emulsions, 480 




soda-water, 299 


Emidsum amygdalse, 497 




sodium phosphate, 91 


English red, 552 




Efflorescence, 90 


blue, 553 




Egg, yolk of, 543 


Enzymes, 421, 549 




oil, 543 


amylolytic, 549 




white of, 543 


pancreatic, 549 




Eteometer, 601 


protolytic, 549 




Elseoptens, 464 


steatolytic, 549 




Elaidic acid, 456 


Eosin, 411 




ElasHca, 471 


Epsom salt, 123, 290 




Elaterin, 500 


Equations, 61, 72 




Elaterinum, 500 


Equisetic acid, 309 




Elder-flower oil, 470 


Equivalents, 62 




Elecampane, 468 


Erbium, 682 




Electric amalgam, 209 


Ergosterin, 475 




current, production of, 132 


Ergot, 475 




Electrodes, 67 


Ergota, 475 




Electrolysis, 28, 67, 363, 384 


Ergo tin, 476 




of potassium acetate, 384 


Ergotine, 475 




of sodium sulphate, 68 


Ergotinic acid, 476 




of sulphuric acid, 68 


Ergotinine, 475 




Electrolytes, 68 


Ericolin, 498 





i 



I 



INDEX. 



709 



Erlangeu blue, 554 
Eriicic acid, 444 
Erythrite, 445, 462 
Erythroretine, 412 
Erythrose, 481 
Erythroxylon coca, 532 
Esculin, see ^sculia. 
Eseramine, 537 
Esere, 537 
Eseridine, 537 
Eseriue, 537 
Eseroliue, 537 
Essence of apple, 405 

greengage, 405 

melon, 405 

mirbane, 407 

mulberry, 405 

pineapple, 405 

quince, 405 
Essences, 465 
Essential oils, 464 
Esters, 401, 447 
Etcbing. 328 
Etbal, 425 
Ethane, 376, 382, 386 

constitution of, 382 

synthesis of, 383 
Ether, 429 

acetic, 283, 403 

aceto-acetic, 404 

compound spirit of, 432 

ethyl, 429 

hydrobromic,see Ethyl bromide. 

nitrous, 335, 401 

ozonic, 577 

petroleum, 387 
Ethereal oil, 432 

salts, 401, 447 
Ethers, 429, 447 

mixed, 432 

sulphur, 432 
Ethiop's mineral, 219 
Ethyl, acetate, 283, 403 

aceto-acetate, 404 

alcohol, 419 

ammonia, 508 

ammonium iodide, 508 

bromide, 398 

butyrate, 405 

carbamate, 455 

chloride, 398 

ether, 429 

-formic acid, 453 

hydride, 386 

hydrogen sulphate, 392, 420, 
431 

hydroxide, 417, 419 

hydroxvlamine, 509 

iodide, 398 



Ethyl, nitrite, 334, 401 

cenathylate, 405 

pelargonate, 405 

sebacate, 405 

series of alcohols, 417 

sparteine, 539 

suberate, 405 

-sulphuric acid, see Ethyl 
hydrogen sulphate. 
Ethylamine, 508 
Ethylate, sodium, 423 
Ethylene, 389, 392 

bromide, 393, 394 

chloride, 393 

diamine, 509 

hydroxide, 417 

iodide, 393 

sulphate, 432 
Ethylidene compounds, 455 

lactic acid, 455 
Ethylmorphine hydrochloride, 517 
Ethylsulphonic acid, 428 
Etymology of names of elements, 37 
Eucalyptol, 467, 468 
Eucalyptus oil, 468 
Eucalyptus, 342 

amygdalina, 468 

cneorifolia, 468 

dumosa, 468 

globulus, 468 

macidata, 468 

odorata, 468 

oleosa, 468 

rostrata, 468 
Euchlorine, 279 
Eugenol, 467 
Euodic aldehyde, 470 
Euouymin, 507 
Euoyiymus, 507 

atropurpureus, 507 
Eupatorium, 507 

perfoliatum, 507 
Euphorbium, 479 
Euphorbon, 479 
Euxanthine, 551 
Evaporation, 76, 107 
Everitt's salt, 267 
Exogonium purga, 501 
Explosion of gas, 27 
Extract of malt, 493 

Goulard's, 224 
Extracts, 592 
Extractum Belladonmr foUonm. 529 

cannabis Tndic.i', 475 

ergofa\ 476 

glyci/rrln/zn\ 500 

mal'ti, 493 

;)/( i/sosti(j}natis, 537 

Saturni^ 223 



710 



INDEX. 



Face-rouge, 323 

Faeces, 572 

Fahrenheit thermometer, 44 

Fats and Oils, composition of, 439 

Fats, etc., analysis of, 681 

solid, 442 
Fatty acids, 440 

matter in urine, 588 

series, 374 

substances, 374 
Fel bovis, 549 

purificatum, 549 
Felspar, 337, 360 
Fenchene, 415 
Fennel-oil, 468 
Fenugreek, 540 
Fer reduit, 163 
Fermentation, 420 

acetic, 282, 421 

alcoholic, 420, 421 

ammoniacal, 421 

butyric, 453 

by soluble ferments, 420 

citric, 309 

lactic, 331, 421 

mannitic, 421 

nitric, 271 

putrefactive, 421 

■viscous, 421 
Ferments, 421 

amylolytic, 549 

organized, 421 

pancreatic, 549 

proteolytic, 549 

soluble, 421 

steatolytic, 549 
Ferratin, 549 
Ferri carhonas, 153 

.saccharatus, 152 

chloridi liquor, 156 

citras, 161 

et ammonii citras, 159 

quantitative determi- 
nation of iron in, 650 
sulphas, 147 
tartras, 161, 351 

et potasii tartras, 159, 161 308 

quantitative determi- 
nation of iron in, 650 

et quininse citras, 161 
solubilis, 160 

et strychninse citras, 161 

hydroxidum, 157 

cum magnesii oxido, 185 

hypophosphis, 329 

lactas, 282 

phosphas solubilis, 161 

pulvis, 163 

pyrophosphas solubilis, 161, 336 



Ferri subcarbonas, 153 
sulphas, 151 

exsiccatus, 151 
granulatus, 151 
tersulphatis liquor, 157, 159 
Ferric acetate, 158, 284, 333, 345 
aceto-nitrates, 162 
ammonium sulphate, 147 
benzoate, 323 
cacodylate, 323 
chloride, 155, et seq. 
anhydrous, 155 
citrate, 161 
ferrocyanide, 326 
gallate, 344 
hippurate, 325 
hydroxide, 157, 165 
hydroxycarbonate, 166 
iodate, 280 
meconate, 332, 344 
nitrate, 162 
oxide, 149, 158 

separation from phosphates 
and oxalates, 359 
oxyacetate, 284 
oxyhydroxide, 149, 157 
oxyiodate, 280 
oxysulphate, 152 
phosphate, 161, 316 

soluble, 161 
salts, 150, 155, et seq. 

analytical reactions of, 164, 

165 
volumetric determination 
of, 637 
succinate, 340 
sulphate, 157 '^ 
tannate, 165, 341 
thiocyanate, 165, 269, 332, 344 
valerate, 347 
Ferricyanide, ferrous, 164, 327 

potassium, 326 
Ferricyanides, 326 
Ferricyanogen, 164, 327 
Ferrocyanide, cupric, 208, 326 
ferric, 164, 326 
ferrous, 164 
potassium, 265, 326 

ferrous, 267 
zinc, 137 
Ferrocyanides, 325 
Ferrocyanogen, 164, 326 
Ferrous ammonium sulphate, 152 
arsenate, 158, 176 
bicarbonate, 149 
bromide, 155 
carbonate, 149, 152 

saccharated, 152 
chloride, 154 



INDEX. 



711 



Ferrous chloride, anhydrous, 156 

citrates, 161 

ferricyauide, 165 

ferrocyaiiide, 165 

hydroxide, 165 

iodide, 154 

phosphate, 153 

potassium ferrocyanide, 267 

salts, 151, et seq. 

analytical reactions of, 164 
volumetric determination 
of, 631, 632, 633, 634 

sulphate, 151 

sulphide, 37, 154, 164, 165 

tartrate, 161 
Ferrum, 39, 150 

reductu7n, 163, 650 
Ferula Foetida, 479 
Ferulaic acid, 479 
Fibrin, 543 

ferment, 544 

insoluble, 544 

vegetable, 546 
Fibrinogen, 544 
Ficus, 482 

elastica, 471 
Fig, 482 
Filicic acid, 444 
Filmarone, 444 
Filter, to dry, 640 

-paper, 115, 639 
Filters, 115 

ashless 639 
Filtrate, 118 
Fine gold. 198 
Fire-clay, 214, 338 

-damp, 385 
Fir wool, 416 

oil. 416 
Fischer's salt, 85, 142 
Fisetin, 551 
Fish-poison, 511 
Fixed oils, 443 

and volatile oils, difference 
between, 443 
Flag, blue, 507 
Flake manna, 445 

white artists', 555 
toilet, 555 
Flame, oxidizing, 136 

reducing, 136 

structure of, 28 
Flare, 442 
Flashing-point, 416 
Flavaspidic acid, 444 
Flax seed, 494 

Fleitmann's test for arsenic, 181 
Flexible collodion, 496 
Flint, 337 



Flint glass, 338 

Flores zinci, 136 

Flour, 488 

Flowers of sulphur, 284 

Fhddextr actum belladonx radicis, 529 

frangulse, 498 

glycyrrhizse, 500 

hemamelkUs, 507 

hydrastis, 530 

ipecacuanhse, 535 
" Fluid magnesia," 125 
Fluorescein, 411 
Fluoric acid, 328 
Fluoride, boron, 318 

calcium, 112, 327 
in bones, 118 

ethyl, 328 

lithium, 104 

silicon, 339 

sodium aluminium, 146 
Fluorides, 327 
Fluorine, 328 

derivation of word, 38 
Fluor-spar, 112, 327 
Fluosilicic acid, 328 
Foeniculum, 468 
Foenugreek, 540 
Foil, tin, 193 
Food, analysis of, 681 
Formaldehyde, 200, 448 
Formalin, 448 
Formate, ammonium, 268 

potassium, 401 
Formates, 324 
Formic acid, 324, 448, 455 
Formica rufa, 324 
Formosa camphor, 472 
Formose, 448, 484 
Formula weight, 59 
Formulae, 59 

calculation of composition per- 
cent, from, 61 

constitutional, 375 

construction of, 59 

empirical, 60, 608 

deduction of, from com- 
position percent., 60 

graphic, 375 

molecular, 60, 608 

structural, 375 
Formyl chloride, 396 
Fousel-oil, see Fusel-oil. 
Fowler's solution, 174 
Foxglove, 499 
Fractional crystallization, 82, 362 

distillation, 362. 373, 419 

elutriation, 134, 362 

fusion, 362 

lixiviatiou, 90, 362 



¥ 



12 



ISBEX. 



Fractional operations, 362 

precipitatioD. 362 

sifting. 355, 362 

solution. 90, 362 

sublimation, 97, 362 
FranguJa, 500 
Franguliu, 412, 500 
Fraukiuceuse, Arabian, 479 

common, 478 
Fraxinus ornus, 445 
Free acids, 352 

determination of, 621 
Freezing-mixture, 288 
French chalk. 555 

tui'peutiue, 415 
Fructose. 482 
Fruit essences, 405 

sugars. 482 
Fuchsine, 555 
Fuller's earth. 333 
Fulminating silver. 237 

mercury. 237 
Fume-cupboard, 100 
Fumeroles. 318 
Fuming nitric acid, 272 

sulphuric acid, 293 
Funnel-tubes, 26 
''Fur" in water-vessels, 301 
Furnace, blast, 149 
Furniture of a laboratory, xv 
Furze, 534 
Fusel-oil. 346, 425 
Fusibility of metals. Table of the, 

597 
Fusible calculus. 5S9. 591 

white precipitate, 218 
Fusion, fractional, 362 
Fustic, 551 

Gab tree. 343 
Gadinine, 511 
Galactose, 483, 486 
Galbanum. 479 
Galena, 222 

argentiferous, 233 
Galipea cnsparia, 534 
Galipine, 534 
Galipot. 474 
Gall of the ox, 549 
Galla, 340 
Gallate, ferric, 343 
Gallic acid. 340, 343, 459 
Gallium, 682 

Gallotannic acid, 340, 459 
Galls, Aleppo, 340 

English, 340 
Gall-stones, 591 
Galvanic test for mercury, 221 
Galvanized iron, 132 



Gambir, 342 
Gamboge, 479, 551 

Indian. 479 

Siam. 479 
Gambogic acid, 479 
Ganga, 475 
Garancin, 552 
Garcinia indica, 443 

Hanburii, 479 

morella, 479 

oil. 443 

purpurea, 443 
Garcinice purpurese oleum, 443 
Garden thyme, 468 
Garlic, essential oil of, 427 
Garnierite, 143 
Gas-analysis, 344, 558 

burners. 29 

coal-, 297, 392, 435 

for balloons, coal, 29 

-lamps, 29 
Gaseous volumes, law of, 51 
Gases, analysis of, 558 

collection of, 20, 21 

correction of the volume of, 46, 
604 
for pressure, 47, 604 
for temperature, 47, 605 

diffusion of. 30 

law of solubility of, in water, 
23 

occlusion of. by spongy plati- 
num, 201 

relative densities of. 48 

specific gravities of. 48. 604 
Gastric juice. 548 
Gaidtherin procurnbens, 458 

oil, 458 
Gaultheric acid, 458 
Gaultherin. 458 
Gay-Lussac's law. 46 
Gelatin -producing substances, 547 
Gelatin. 547 

sitgar of. 550 

tannate. 342 

test solution, 547 

tests for, 548 

vegetable, 494 
Gelatinum, 547 
Gel id I urn come urn, 494 
Gelose, 494 
Gelsemine. 535 
Gelseminic acid. 535 
Gelseminine, 535 
Gel semi urn, 535 

elegans, 535 

nitidnm, 535 
Gentian-bitter, 500 
Gentiana, 500 



INDEX, 



713 



Gentiana lutea, 500 
Gentianicacid, 500 
Gentiogeuin, 500 
Geutiopicriu, 500 
Gentisic acid, 500 
Gentisin, 500 
Geraniol, 469 
Geranium macidatum, 343 

oil, 468 
German silver, 132, 143 

yeast, 420 
Gliatti, 494 
Gin, 422 
Gingelly oil, 444 
Ginger-grass oil, 468, 469 

oil, 471 

oleoresin, 478 
Gingerol, 531 
Girdwood and Rogers's method for 

detecting strychnine, 566 
Glacial acetic acid, 283 

phosphoric acid, 314 
Glance, bismuth, 227 
Glass, 140, 338 

liquor, 339 

of antimony, 186 

rods, 75 

soluble, 339 

tubes, to bend, 21 
to cut, 21 
to draw out, 116 

water-, 338 
Glauber's salt, 253 
Globulins, 546 
Glucinum, 682 
Glucose, 420, 482 
Glucoses, 481 
Glucosides, 496 
Glue, 547 
Glutaric acid, 463 
Gluten, 479 
Glutin, 479, 547 
Glyceric acid, 455 
Glycerin, 437 

tests for, 438 
Glycerinum, 437 
Glycerites, 592 
Glyceriinm. acitli tannici, 341, 438 

amyli, 438 

borofilycerini, 319 

ferri, quininse, et strychninx, 
plwspliatum, 438 

hydrastis, 438 

phenolis, 433, 438 
Glycerol, 437 
Glycerose, 481 
Glyceryl, 437 

borate, 320 

caproate, 442 



Glyceryl caprylate, 442 

hydroxide, 417, 437 

hydroxyoxalate, 324 

laurate, 442 

myristate, 442 

nitrate, 438 

oleate, 439 

palmitate, 442 

ricin oleate, 444 

rutate, 442 

tristearate, 439 
Glycocholates, 550 
Glycine, 550 
Glycocoll, 550 
Glycogen, 491 
Glycol, 436 

-aldehyde, 446 

oxidation of, 461 

trichlorbutylidene, 453 

trichlorethylidene, 453 
Glycollic acid, 446, 455 
Glycols, 435 

aromatic, 436 
Glycuronic acid, 577 
Glycyrrhetin, 500 
Glycyrrhiza, 485, 500 
Glycyrrhizate ammonium, 501 

calcium, 501 
Glycyrrhizic acid, 500 
Glycyrrhizin, 500 
Glyoxal, 446 
Glyoxylic acid, 455 

series, 455 
Gmelin's test for bile, 550 
Gnoscopine, 517 
Goa powder, 412 
Gold, 197 

analytical reactions of, 198 

chloride, 198, 570 

test solution, 198 

coin, 197 

derivation of word, 38 

dust, 197 

earth, 551 

fine, 198 

jewellers', 197 

leaf, 197 

mosaic, 196 

mystery, 197 

oclire, 551 

perchloride, see Auric chloride, 

sodium thiosulphate, 295 

sulphide, 198 

yellow, 551 
Golden seal, 530 

syrup, 485 
Gooseberry, 482 
Gossypi cortc.v, 507 
Gossypiiim purijicatum, 495 



714 



INDEX. 



Gothite, 149 
Goulard's cerate, 224 

extract, 223 

water, 224 
Graliam's dialytic process, 680 

law of difl'usiou, 30 
Grain tiu, 193 
Grains of paradise, 469 
Gramme, 41 

molecule, 55 
volume, 60 
Grnnatum, 342, 537 
Granulated phosphorus, 312 

tin, 193 

zinc, 25 
Granulose, 489 
Grape, 482 

juice, 305 

sugar, 305, 482 
Grapes, dried, 305 

sugar in, 482 
Graphic formulae, 375 
Graphite, 36 

Grass oils (3), 468, 469, 471 
Gravel, 582 
Gravimetric quantitative analvsis, 

638 
Gravity, specific, 47, 599, et seq. 
Gray powder, 210 
Green, Brunswick, 184 

Chinese, 555 

copperas, 152 

emerald, 555 

hellebore, 501 

iron iodide, 154 

pigments, 555 

Scheele's, 184 

Schweinfurth, 184 

ultramarine. 555 

vitriol, 152, 292 
Greengage essence, 405 
Griess's reagent, 335 
Griffith's mixture, 153 
Grindelia, 535 

robusta, 535 
Grindeline, 535 
Ground-nut oil, 444 
Group tests, 242 
Guaiacin, 501 
Guaiacol, 433 

carbonate, 433 
Guaiacolis carbonas, 433 
Guaiaconic acid, 501 
Guaiacum, 501 

officinale, 501 

resin of, 476, 501 
Guaiaretic acid, 501 
Guaiaretin, 501 
Guaiareiinic acid, 501 



Guanine, 571 

Guano, 346 

Guaraua, 531 

Guaranine, 531. See Caffeine 

Guaza, 475 

Guilandina bonduceUa, 507 

Guinea grains, 469 

Gulancha tinospora, 507 

Gulose, 483 

Gum, 121, 494 

-acacia, 121, 494 

-arabic, 121, 494 

Benjamin, 321, 456 

benzoin, 456 

British, 492 

cherry-tree, 494 

Indian, 494 

red, 468 

resins, 479 

tragacanth, 121. 494 
Gummate, calcium, 121 

lead, 121 
Gummic acid, 494 
Gunj, 501 
Gunjah, 475 
Gun-cotton, 495 

-metal, 193 
Gunpowder, 275 
Gurjun Balsam, 477 
Gutta Percha, 471 
Gutzeit's test for arsenic, 182 
Gynocardia odorata, 444 

oil, 444 
Gypsum, 112, 290 

H^MATEIN, 553 
Hsematite, brown, 149 

red, 149 
Hsematoporphyrin, 574 
Hsematoxyliu, 553 
Hxmatoxylon, 342, 553 
Haemoglobin, 546 
Halide, 391 
Halogens, 265 
Haloid salts, 265 
Hamamelidis cortex, 507 

folia, 507 
Hamamelis virginica, 507 
Hambro' blue, 553 
Hard soap, 441 
Hardness of water, 301 
Hart's test, 262 
Hashish, 475 
Haw, black, 507 
Heat, atomic, 58 
Heavy carburetted hydrogen, 392 

magnesia, 126 

magnesium carbonate, 124 
oxide, 125 



i 



c 

I 



INDEX. 



715 



Heavy spar, 109, 290 

white, 109, 555 
Hectare, 41 
Hedeoma, 469 

pulegioides, 469 
Helenin, 468 
Heliotrope, 503 
Helium, 25 
Hellebore, black, 501 

green, 501, 536 

white, 536 

American, 536 
Helleborein, 501 
Helleborin, 501 
Helleborus niger, 501 

viridis, 501 
Heller's test for albumin in urine, 

575 
Hemidesmic acid, 325 
Hemlock, 468, 533 

fruit, 533 

leaves, 533 
Hemp, Canadian, 507 

Indian, 474 
Hempseed calculi, 591 
Henbane, 535 

Henry and Dalton's laws, 23 
Heptane, 386 
Heptoic aldehyde, 468 
Heptylene, 392 
Herapathite, 520 
Heroin, 516 
Hesperidene, 466 
Hesperidin, 507 
Hevea, All 

Hexabasic acids, 463 
Hexabromobenzeiie, 407 
Hexachlorobenzene, 407 
Hexahydric alcohols, 445 
Hexahydrobenzene, 411 
Hexa-hydro-pyridine, 538 
Hexamethylenamina, 448 
Hexamethylenamine, 448 
Hexamethylenetetramine, 418 
Hexane, 386 
Hexylene, 392 
Hippuric acid, 325, 583 
Hips, 484 

Hoffmann's anodyne, 432 
Hoffner's blue, 553 
Hofmann's method for detection of 

arsenic and antimony, 203 
Hollway's smelting process. 205 
Homatropinx hi/drobromidum, 528 
Homatropine, 528 

hydrobromide, 528 
a-Homochelidonine, 538 
0- — , 538 
Homologous series, 380 



Homologues, 380 

general formulae for, 380 
Homology, 380 
Homonataloin, 413 
Homopterocarpin, 552 
Homoquiuine, 523 
Homotartaric acid, 463 
Honey, 484 

borax, 319 

clarified, 484 
Honeydew, 486 
Hop, 478, 536 

bitter, 478 

essential oil of, 478 
Horehound, 507 
Horse-chestnut, 535 
Horseradish oil, 466 
Houzeau's test for ozone, 261 
Huile de Cade, 478 
Humulus, 478, 536 

lupulus, 478, 536 
Hydrargyri chloridum corrosovium, 
214 
mite, 215 

iodidum florum, 210 
rubrum, 211 

oxidum flavum, 216 
rubrum, 216 

sulphuretum cum sulphure, 219 
Hydrargyrum, 39, 209 

ammoniatum, 218 

cum creta, 210 
Hydrastine, 530 

acid tartrate, 530 
Hydrastis, 530 

canadensis, 530 
Hydrate, see Hydroxide. 

butyl chloral, 453 

chlorine, 254 
Hydration, 440 
Hydraulic cement 338 
Hydrazine, 510 
Hydrazobenzene, 407 
Hydride, antimony, 191 

cuprous, 330 

ethyl, 386 

methyl, 385 

silicon, 339 
Hydriodic acid, 258, 259 

dilute, 260 
Hydrium, 26 
Hydrobromic acid, 255 
dilute, 257 

preparation, Marshall's 
method, 256 
Scott's method, 256 
Hydrocarbons, 375 

acetylene series. 394 

anthracene series, 411 



716 



J.XDEX. 



Hydrocarbons, benzene series, 406 
"crackiug" of, 373 
dihydroxyl derivatives, 435 
mouohydroxyl derivatives, 417 
napthalene series, 411 
normal paraffin, 381 
olefine series, 389 
paraffin series, 376 
polybydroxyl derivatives, 445 
saturated, 376 
series of, 376 
terpene series, 415 
trihydroxyl derivatives, 437 
unsaturated, 389 
Hydrochloric acid, 35, 252 

analytical reactions of, 255 
antidote, 255 
commercial, 253 
dilute, 253 

in organic mixtures, detec- 
tion of, 563 
volumetric determination 
of, 623 
Hydrochloride, apomorphine, 517 
morphine, 513 
quinine, 519 
Hydrocinchonidine, 523 
Hydrocotarnine, 517 
Hydrocotoin, 499 
Hydrocotyle asiatica, 507 
Hydrocotyles folia, 507 
Hydrocyanic acid, 265, 326 

analytical reactions of, 268 
antidotes to, 270 
diluted, 267 
from bitter almond and 

cherry laurel, 268, 497 
in organic mixtures, detec- 
tion of, 564 
in the blood, 269 
Schonbein's test for. 270 
volumetric determination 
of, 625 
Hydroferricyanic acid, 326 
Hydroferrocyanic acid, 325 
Hydrofluoric acid, 327 
Hydrogen, 25 

acetate, beuzoate, borate, chlo- 
ride, nitrate, sulphate, etc., 
see the respective acids, acetic, 
benzoic, etc. 
antimonide, 191 
antimoniuretted, 191 
arsenide, 180 
arseniuretted, 180 
combination with chlorine, 35 
combustion of, 26 
derivation of word, 38 
dioxide, 109 



Hydrogen, explosion of, 27 

heavy carburetted, 392 

in artificial light-producers, 27 

light carburetted, 385 

lightness of, 29 

phosphides, 328 

phosphuretted. 328 

preparation of, 25 

properties of, 26, 29 

quantitative determination of, 
in organic compounds, 670, 
et seq. 

salts, 65 

siliciuretted, 339 

sulphide, 100, 154, 284 
oxidation, of, 101 

sulphuretted, 100, 284 

test for arsenic, 179 

used for balloons, 29 

weight compared with air, 29 

weight of 1 litre, 606 

weight of 100 cubic inches, 606 
Hydrogenium 25 
Hydrolysis, 440, 486 
Hydrometers, 601 
Hydroquinine, 523 
Hydroquinone, 436, 498, 518 
Hydrosulphide, ammonium, 99, 287 

potassium, 287 

sodium, 287 
Hydrosulphides, 287 

analytical reactions of, 287 
Hydrosulphuric acid, 284 
Hydrous butvl chloral, 453 

salts, 90 ' 
Hydroxide, aluminum, 146, 148 

ammonium, 94 

barium, 109 

bismuth, 231 

cadmium, 233 

calcium. 114 

chromic, 169 

cupric, 207 

ethyl, 419 

ferric, 157 

ferrous, 165 

manganese, 140 

methyl, 418 

nickel, 144 

potassium. 72 

sodium, 86 

stannous, 196 « 

strontium. 111 

zinc, 136 
Hydroxides, bases are probably, 64 

composition of, 64, 72 

identified, 361 

of the hydrocarbon radicals, 
417 



INDEX. 



717 



Hydroxyacetic acid, 455, 457 
Hydroxybenzoic acid, ortho-, 457 

aldehyde, ortho-, 458 
Hydroxybenzyl alcohol, 437 
Hpdroxybutyric acid, 455 
Hydroxy cap roic, 455 
Hydroxycaprylic acid, 455 
Hydroxycarbonate, copper, 205 

lead, 223, 226, 

magnesium, 124, 302 

zinc, 134 
Hydroxyforroic acid, 455 
Hydroxyl, 273, 282 
Hydroxylamine, 509 

hydrochloride, 509 
Hydroxy-lauric acid, 455 
Hydroxy - propane - tricarboxylic 

acid, 462 
Hydroxypropionic acid, 455 
Hydroxysuccinic acid, 461 
Hydroxytoluic acid, 457 
Hydroxyvaleric acid, 455 
Hygiene, 18 
Hygrophila, 507 

spinosa, 507 
Hyoscine, 535 

hydrobromide, 535 
Hyoscinse hydrohromidum, 535 
Hyoscyaminse hydrobromidium, 535 

sulphas, 535 
Hyoscy amine, 527, 535 

hydrobromide, 535 

sulphate, 535 
Hyoscyamus, 535 

niger, 535 
Hyper-, meaning of, 155 
Hypnone, 464 

Hypo-, meaning of, prefix, 330 
"Hypo," 294 

use of, in photography, 295 
Hypobromites, 257 
Hypochloride, sulphur, 287 
Hypochlorite, calcium, 119 

sodium, 91 
Hypochlorites, 276 
Hypochlorous acid, 120, 276 
Hypogseine, 444 
Hypophosphite ammonium, 329 

barium, 329 

calcium, 329 

ferric, 329 

manganese, 138, 329 

potassium, 329 

quinine, 329 

sodium, 329 
Hypophosphites, 328 
Hy])ophosplioric acid, 336 
Hypophosphorous acid, 328, 336, 337 
Hyposulpliites, see Thiosulphates. 



Hyposulphurous acid, 296 
Hypothesis, Avogadro's. 53 

-ic, meaning of, 77, 81, 151 

Icacin, 478 

Iceland moss, 323, 491 

-ide, meaning of, 81 

Igasurine, 525 

Ignition, 107 

lllicium veruni, 466 

Illuminating agents, analysis of, 681 

Imidazole acid, 510 

Imino-bases, 509 

Incense, 480 

Incineration, 107 

of filters in quantitative analy- 
sis, 639 
Indelible ink, 236 
Indestructibility of matter, 17 
India senna, 578 ' 
Indian azadirach, 507 

gamboge, 479 

gum, 494 

hemp, 474 

ink, 555 

ipecacuanha, 534 

licorice, 501 

melissa oil, 471 

mustard, 427 

pennywort, 507 

red, 552 

yellow, 551 
India-rubber, 471 

vulcanized, 471 
Indican, 553 
Indicator, 611 
Indiglucin, 553 
Indigo, 276, 553 
' artificial, 554 

blue, 276 

reduced, 553 

sulphate, 276 

test solution, 276 

-white, 553 

wild, 529 
ludigofera, 553 
Indigogen, 553 
Indigotin, 554 

disulphonic acid, 276 
Indium, 682 

Infusible white precipitate, 219 
Infusions, 592 
Infusorial earth, 339, 546 
Ink, black. 165. 341, 555 

indelible. 236 

Indian. 555 

invisible, 142 

marking. 236 

printer's, 555 



718 



INDEX. 



Ink, sympathetic, 143 

Inosite, 483 

Insecticide, 477 

Insoluble substances, analysis of, 

360 
Introduction, 17 
Inula Helenium, 468, 491 
Inulenin, 491 
Inulic anhydride, 468 
Inulin, 491 
Inulol, 468 
Invertase, 420 
Inverted sugar, 482 
Invisible ink, 142 
lodal, 453 
lodate, ferric, 280 

potassium, 80, 280 

silver, 280 
lodates, 258, 280 
Iodic acid, 260, 280 
Iodide, ammonium, 98 

antimonious, 186 

arsenous, 173 

bismuth, 229 

and potassium, 570 

cadmium, 232 

cuprous, 206, 208, 261 

cyanogen 259 

dimercuri-ammonium, 219 

ethyl, 398 

ferrous, 154 

hydrogen, 259 

iron, 37, 154 

lead, 224, 263 

mercuric, 210, et seq., 218, 264 

mercurous, 210, 220 

nitrogen, 260, 

potassium, 79, 260 

detection of iodate in, 80 
mercuric, 220 

silver, 237, 260, 280 

sodium, 91 

starch, 80, 260, 480 

sulphur, 259, 287 

zinc, 134 
Iodides, 258, 

analytical reactions of, 260 

of mercury, 210, et seq. 

quantitative determination of, 
627, 660 

separation of, from bromides 
and chlorides, 261 
Iodine, 36, 258 

atomic weight, 259 

its analogv to chlorine and bro- 
mine, 264 

derivation of word, 38 

detection of, in mercuric iodide, 
212 



Iodine, moisture in, 660 

molecular formula of, 259 

solution of, 259 

specific gravity, 264 

standard solution of, 628 

tincture of, 259 

volumetric determination of, 
636 

water, 259 
lodo-salicylic acid, 458 
Iodoform, 401, 424 
lodofornuun, 401 
lodol, 511 
lodolum, 511 
lodopyrroi, 511 
lodum, 258 
Ionization, 363 
Ions, 363 
Ipecacuanha, 534 

wine, 534 
Ipecacuanhic acid, 534 
Ipomsea hederacea, 502 

orizabensis, 501 

purga, 501 

simulans, 502 

turpethum, 213, 502 
Iridin, 507 
Iridium, 199, 201, 682 

chloride, 570 
Iris florentina, 469 

versicolor, 507 
Irish moss, 494 
Irisin, 507 
Iron, 149 

acetate, 158, 283, 333, 345 

acetonitrates, 162 

alum, 147 

ammonium citrate, 159 

and ammonium tartrate, 

161, 308 
potassium tartrate, 159, 
161, 308 

analytical reactions of, 164 

and quinine citrate, soluble, 
161 

arsenate, 158, 176, 185 

arsenio-sulphide, 173 

bromide, 155 

carbonate, 152 

cast-, 150 

chlorides, 154. 155, et seq. 

compounds, nomenclature of, 
149 

derivation of word, 38 

detection of, in presence of 
aluminium and chromium, 
170. 171 

ferrocyanides, 165, 326 

galvanized, 132 



INDEX. 



719 



Iron, gravimetric determination of, 
G49 
hydroxide, 157 

in official compounds, determi- 
nation of, 649 
iodate, 280 
iodide, 37, 154 
maltosate, 153 
manufacture of, 149 
meconate, 332 
nitrate, 162 
ore, magnetic, 119 
needle, 149 
spathic, 149 
specular, 149 
oxide magnetic, 149 

determination of iron 
in, 633 
red, 158 
oxyhydroxides, 149, 157 
oxyiodate, 280 
oxysulphate, 152 
perchloride, see Ferric chloride 
persulphate, see Ferric sulphate 
phosphates, 153, 316 
pill, 153 

potassium tartrate, 161 
protosulphate, 151 
pyrites, 149, 284 
quantitative determination of, 
gravimetric, 649 
volumetric, 631, 637 
red oxide of, 158 
reduced, 162 
rust, 150 
saccharated carbonate, 152 

volumetric determina- 
tion of, 632 
salts, nomenclature of, 150 
scale, compounds of, 158 
separation of, from aluminium 
and chromium, 170, 171 
from phosphates and oxa- 
lates, 359 
sodio-citrate, 161 
sucrate, 152 
sulphate, 157 
sulphide, 37, 154, 165 
tartrate, 161 
thiocyanate, 165, 345 
M^ine of, 161 

bitter, 161 
wrought, 150 
Ironstone, clay, 149 
black band, 149 
chrome, 166 
Isaconitine, 526 
Isatropyl-cocaine, 532 
Isinglass, 547 



Isinglass, Japanese, 494 
Iso, meaning of, 501 
Isoamyl hydride, 386 
Isobarbaloin, 413 
Isobutane, 386 
Isoheptoic acid, 469 
Isomeric substances, 379 
Isomerides, 379 
Isomerism, 379, 390 
Isomers, 379 
Isomorphous bodies, 133 
Isonandra gutta, 471 
Isonitriles, 447 
Isopentane, 386 
Isophthalic acid, 462 
Isoprene, 475 
Isopropylacetic acid, 453 
Isopropyl iodide, 383 
Isorottlerin, 477 
Iso-thiocyanate, acrinyl, 427 

allyl, 427, 466, 470 
Iso-valerate, zinc, 136 
Iso-valeric acid, 347, 453 
Ispaghul, 495 
-ite, meaning of, 81 
Ivory-black, 555 

Jaboridine, 537 

Jaborine, 537 

Jalap, Indian substitute for, 213 

Mexican male, 501, 505 

resin, 476, 501, 502 

Tampico, 502 

true, 501 
Jalapa, 502 
Jalapin, 501 
Jalapurgin, 501 
Japaconitine, 527 
Japanese belladonna, 529 

isinglass, 494 
Jasmine, yellow, 535 
Jaime brilliant, 232 
Jelly, vegetable, 494 
Jequeritin, 501 

Jequerity or jequirity, 501, 547 
Jequerityzymase, 501 
Jervine, 536 
Jeweller's gold, 197 
Juniper camphor, 469 

oil, 469 

tar oil, 478 
Junipcrus oxycedrus, 478 

sabina, 470 

Kainite. 71 
Kairine, 512, 523 
Kairoline, 523 
Kaladana resin, 502 
Kali, 39 



720 



INDEX. 



Kalium, 39 
Kamala, 477 
Kauo, 342 
Kaolin, 338 
KaoUniim, 338 
Kariyat, 507 
KaVa, 507 
Kavse rhizoma, 507 
Kelp, 259 
Kermes, 189 

mineral, 189 
Ketone chloroform, 399 
Ketones, 463 
Ketoses, 481 
Kieselguhr, 545 
Kieserite, 123 
Kiln, 114 

Kinates, see Qiiinates. 
Kinetic theory, 30 
King's blue, 553 

yellow, 551 
Kino, 342 

Australian, 342 
Kiilone, see Quinone. 
Kjeklahl's process, 674 
Klunge's reaction, 413 
Kokum butter, 443 
Kola-nut, 530, 539 
Kosin, 476 
Koussin, 476 
Kousso, 476 
Krameria, 342 
Krypton, 32, 33 
Kunch, 501 

Labokatoey furniture, xv. 
Laburnum, 534 
Lac, 553 

dye, 553 
Lactams, 504 
Lactate, calcium, 331 
Lactates, 331 
Lactic acid, 331, 455 

volumetric determination 
of, 623 
series of acids, 455 

relations to acetic and 
glyoxylic Series, 456 
Lactims, 504 
Lacometer, 545, 601 
Lactone, 481, 504 
Lactones, 504 
Lactophosphate, calcium, syrup of, 

331 
Lactose, 486 
Lactuca, 507 
Lactucnrinm. 507 
Lactucin, 507 
Ladies' slipper, .507 



Lsevofotation, 306 
Lfevotartaric acid, 306 
Lffivulose, 482 
Lakes, 148, 555 

Lamp, Dobereiner's self-lighting, 
201 

-black, 297, 555 
Lana philosophica, 136 
Lauoline, 440, 441 
Lanthanum, 171, 172, 682 
Lanthopine, 517 
Lapis lazuli, 554 
Lappa, 507 

officinalis, 507 
Larch bark, 342 
Lard, 442 

benzoinated, 442 

purified, 442 
Larix europsea, 342 
Larixin, 342 
Larixinic acid, 342 
Laudanine, 517 
Laudanosine, 517 
Laughing-gas, 97 
Laurate, glyceryl, 442 
Laurel-camphor, 472 
Laurie acid, 442 

aldehyde, 470 
Laitrocerasi folia, 479 
Lavandula spica, 468 
Lavender flowers, oil of, 469 

water, 465 
Law, Boyle's, 46 

Charles's, 46 

Dulong and Petit's, 58 

Gay Lussac's, 46 

Graham's, 30 

Henry and Dalton's, 23 

of constant proportions, 51 

of difl'usion of gases, 30 

of indestructibility of matter, 
17 

of multiple proportions, 51, 275, 
296 

of solubility of gases in liquids, 
23 

Periodic, 364 
Laws of chemical combination by 
weight, 50, 51 

of chemical combination by 
volume, 51 
Lead, 222 

acetate, 223 

volumetric determination 
of, 657 

analvtical reactions of, 225 

antidotes of, 226 

black-, 298 

carbonate, 226 



INDEX. 



721 



Lead, chloride, 225 

chroniates, 167, 169, 226 

cyanate, 324 

derivatiou of word, 38 

detection of, in organic mix- 
tures, 561, 562 

dioxide, see Lead peroxide. 

gravimetric determination of, 
656 

gumma te, 121 

hydroxide, 226 

hydroxv-carbonate, 223, 226 

iodide, 224, 264 

malate, 332 

nitrate, 224 

oleate, 224 

oxide, 222 

oxyacetate, 223 

oxychromate, 167 

peroxide, 222, 224 

-plaster, 225 

puce-colored oxide, or peroxide, 
222 

pyrophorus, 163 

red, 222, 552 

shot, 222 

subacetate, 223 

sugar of, 223 

sulphate, 226 

sulphide, 225 
native, 222 

test for, in water, 225 

tree, 227 

white, 223, 555 
Leadstone, 149 
Leaf, gold, 197 

-green, 554 
Leather, 341 
Leblanc process, 254 
Lecanora, 554 
Lecith-albumins, 543 
Lecithin, 510 
Lecithins, 543 
Lees, 305 
Legumin, 546 
Lemon-chrome, 226 

grass oil, 471 

juice, 308, 310 

determination of mineral 
acids in, 664 

oil, 466 
Length, unit of, 40 
Lentisk tree, 476 
Lepidolite, 103 
Leptandrin, 507 
Leptandra, 507 
Lettuce, 535 
Leucic acid, 455 
Leucine, 510, 583 

46 



Leucomaines, 510 
Levisticum, 479 
Levulose, 482 
Lichen blue, 554 

sugar, 445 
Lichenin, 491 
Lichenstearic acid, 323 
Licorice, 500 

Indian, 501 

root, 485 

Spanish, 500 

sugar, 485, 501 
Light, carburetted hydrogen, 385 
Lignin, 495 
Lignite, 339 
Lime, bisulphite, 289 

carbonate, see Calcium carbon- 
ate. 

caustic, 113 

chloride, 119 

chlorinated, 119 

juice, 308, 310 

determination of mineral 
acids in, 664 

-kiln, 114 

-oil, 466 

quick-, 113 

slaked, 114 

sulphurated, 120 

syrup of, 114 

water, 114 
Limestone, 112 

magnesian, 123 

mountain-, 123 
Limonenes, 415 
Limonis cortex, 466 

saccus, 310 
Linalyl acetate, 467 
Linamarin, 498 
Linalool, 469 
Liniments, 592 
Litiimentum ammonix, 441 

helladoniise, 529 

calcis, 441 

camphorcf, 473 

saponis, 441 
mollis, 441 
Linkage of atoms, 375, 410 
Linoleine, 443 
Linoxyn, 443 
Linseed, 443, 

ground, 443 

-oil, 443 

boiled, 443 

-tea, 494 
Linum, 443, 494 
Lipase, 549 
liipuria, 588 
Liquid, camphor, 472 



722 



INDEX, 



Liquid petrolatum, 388 
Liquidamber orieidalis, 4(50 
Liquids, si)ecific gravity of, 599 

official specific gravities of, 600 
Liquor, acidi arsenosi, 174 
amiHoitii acetatis, 96 
arseni et hydrargyri iodidi, 173 
calcis, 114 

chlori coinpositns, 254 
ferri et ammonii acetatis, 650 

deteruiiiiatiou of 
iron in, 650 
chloridl, 156 

determinatiou of 
iron ill, 650 
subsid^jhatis, deterniiiiatioii 

of iron iu, 650 
tersidphatis, 156, 159 

determination of iron 
in, 650 
fonnaldehydi, 448 
hydrargyri nltratis, 212 
lodi compositus, 259 
magnesii citratis, 126 
2)lumbi snbacetatis, 223 

dUutjis, 224 
potassii hydroxidi, 72 

specific gravity of, 601 
to prepare, 72 
potassii arsenitis, 174 
sodee chlorinafse, 91, 277 
sodii arsenitis, 176 
zinci chloridi. 134 
Liquorice, see Licorice. 
List ofapparatus, xiv. 

chemical substances, xvi. 
reagents, xv. 
Litharge, 222 
Lithates, 346 
Lith'ii benzoas, 104, 323 
bromidum, 104 
carbonas, 103 
citras, 104 

effervescens, 104 
saJicylas. 104 
Lithic acid, 346 
LitMum, 103 

analytical reactions of, 104 
benzoate, 323 
bromide, 104 
carbonate, 103 
chloroplatinate, 104 
citrate, 104 

derivation of word, 38 
flame, 105 
fluoride, 104 
salicylas, 104 
silicate, 104 
urate, 104 



Litmus, 99, 554 

liaper, 99 

test solution, 99, 620 
Litre, 41 

relation of, to liquid gallon, 42 
Liver of sulphur, 73 
Lixiviation, 89 

fractional, 90, 362 
Loadstone, 149 
Loaf sugar, 484 
Lobelia, 536 

inflata, 536 
Lobeline, 536 
Lodestone, 149 
Loganetin, 502 
Loganin, 502 
Logwood, 342, 553 

solution of, bleached by chlo- 
rine, 35 
Lokas, 554 
Long pepper, 538 
Looking-glasses, 193 
Louisa-blue, 554 
Lovage, 479 
Lozenge, see Trochischi. 
Lozenges, 592 

potassium chlorate, 278 

sodium bicarbonate, 87, 89 
Lucifers, 30 
Lump-sugar, 484 
Lunar-caustic, 235 
Lupulin, oleo-resin of, 478 
Lupuline, 536 
Lupulinic acid, 478 
Lnpidinnm, 478, 536 
Lupidus, 507 
Luteolin, 552 
Lutidine, 512 
Luting, fire-clay, 214 
Lycopodine, 444 
Lycopodium, 444 

clavatum, 444 
Lyddite, 435 

Mace, fixed oil of, 442 

volatile oil of, 469 
Macleya cordata, 538 
Macleviue, 538 
Madder, 411, 552 
Magenta, 555 
Magnesia, 125 

alba, 302 

calcined, 126 

fluid, 125 

heavy, 126 

mixture, 315 
Magnesian limestone, 123 
Magnesii carbonas, 124 
' oxidum, 126, 185 



INDEX. 



723 



Magnesii oxidnm jjonderosum, 126 

sulphas, 123 

effervescens, 124 
Magnesite, 123 
Magnesium, 123 

aluminite, 146 

ammonium arsenate, 127 
phosphate, 126, 315 
sulphate, 667 

analytical reactions of, 126 

basic carbonate, 301 

carbonate, 123, 124, 126, 301 
Pattinson's process, 124 

chloride, 123 

citrate, 126 

copaivate, 477 

derivation of word, 38 

detection of, in presence of 
barium, strontium, and cal- 
cium, 128 

hydroxycarbonate, 124 

oxide, 125 

phosphate, in bones, 117 

quantitative determination of, 
647 

separation from barium, stron- 
tium, and calcium, 128 

silicate. 337, 555 

silicidei 339 

sulphate, 123, 290 

use in Marsh's test, 181 
Magnetic iron ore, 149 
Magnolia, 507 

Magpie test for mercury, 221 
Maize starch, 487, 490 (fig.). 
Malachite, 205 
Malate, atropine (acid), 527 

calcium, 332 

lead, 332 

nicotine, 537 

potassium, 332 
Malates, 332 
Male fern, oil of, 444 
Malic acid, 332, 461, 463 

series of acids, 461 
Mallovs^ tea, 494 
Malonic acid, 463 
Malt, 488, 493 

extract, 493 

substitutes, 483 

vinegar, 282 
Maltosate, iron, 153 
Maltose, 483, 484 
Malfum, 493 
Mandelic acid, 497 

tropine ester of, 528 
Manganate, potassium, 81, 139 

sodium, 139 
Manganese, 138 



Manganese, analytical reactions of, 
138, et seq. 

blacls; oxide, 138, 254 

borate, 140 

Crums's test for, 141 

derivation of word, 39 

dioxide, precipitated, 138 

hypophosphite, 138, 329 

Marshall's test for, 141 

quantitative analysis of black 
oxide, 648 

separation of, from nickel, co- 
balt, and zinc, 140 
■ sulphate, 138, 254 
Mangani dioxidum prsecipitatum, 138 

hypophosphis 138, 329 

sulphas, 138 
Manganite, 139 
Manganous chloride, 138 

hydroxide, 140 

sulphate, 138, 254 

sulphide, 140 
Mangosteen oil, 443 
Manihot, starch of, 490 (fig.) 
Manna, 445 
Mannite, 445 
Mannitol, 445 
Mannonic acid, 445 
Mannosaccharic acid, 486 
Mannose, 445, 483, 486 
Manures, analysis of, 681 
Maranta, starch of, 490 (fig.) 
Maraschino, 422 
Marble, 112 
Margarine, 442 
Margosa, 507 
Marigold, 507 
Marine soap, 443 
Marking ink, 236 
Marl, 146 
Marrubein, 507 
Marrubium, 507 
Marseilles soap, 441 
Marshall's method for preparing 
hydrobromic acid, 256 

test for manganese, 141 
Marsh-gas, 385 

series, 376 
Marshmallow, 494 
Marsh's test for arsenic, 179, 182 
Mass, unit of, 41 
Massa hydrargyri, 210 
Massicot, 222 
Mastic, 476 
IMastichic acid, 476 
]\Iasticin, 476 
l\rate, 530 
3raticie folia, 507 
Matico, 507 



724 



INDEX, 



Matricaria chamomiUa, 466 
Matter, iudestructible, 17 
Mauve, 498, 555 
Maximum density point of water, 

47 
]May-apple, 476 
Mayer's reagent, 570, 616 
Meadow-sweet, 458, 503 

oil of, 458, 503 
Measurement of atmospheric pres- 
sure, 44 

of temperature, 43 
Measures, 40, et seq. 
Mechanical mixture and chemical 

combination, 37. 49 
Meconate, calcium, 332, 514 

ferric, 332, 515 

morphine, 513 
Meconates, 333 

distinction of, from acetates 
and thiocyanates, 333, 345 
Meconic acid, 332, 513 
Meconidine, 517 
Meconin, 517 
Meconoisin, 517 
Medicated waters, 465 
Meerschaum, 337 
Mel, 484, 485 

depuratuin, 484 
MeMeuca leucadendron, 467 
Melam, 345 
Melasses, 485 
Melegueta pepper, 469 
Melezitose, 486 
Melia azadirachta, 507 
Melissa oil, 471 
Melissic acid, 453, 455 
Melissyl alcohol, 426 

palmitate, 426 
Melitose, 486, 
Melitriose, 486 
Mellitic acid, 463 
Mellon, 345 
Melon essence, 405 

pumpkin seeds, 507 
Melting-point, determination of. 

596 
Melting-points of metals, 597 

of otiicial substances, 597 
Memoranda, analytical, 246, 350 
Meniscus, 613 

Menispermum canadense, 530 
Mentha arvensis, 469 

piperita, 469 

2)HleqiHm, 469 

viridis, 469 
Menthol, 427, 469 
Mcnthone, 469 
Mercaptaus, 428 



Mercurial ointment, 210 

plaster, 210 
Mercurialine, 509 
Mercurialis annua, 509 

perennis, 509 
Mercuri-ammonium chloride, 218 
Mercuric chloride, 213 

chlorosulphide, 219 

cyanide, 266 

iodide, 210, et seq., 264 

nitrate, 212 

oleate, 440 

oxide, 216 

oxychloride, 276 

oxynitrates, 212 

oxysulphate, 213 

phenate, 434 

potassium iodide test solution, 
616 

salts, analytical reactions of, 
218 

sulphate, 212 

sulphide, 215, 219 

thiocyanate, 345 
Mercuritus vitse, 187 
Mercuros-ammonium chloride, 220 
Mercurous acetate, 284 

chloride, 213, 215, 221 

chromate, 169, 221 

iodide, 210, et seq., 220 

nitrate, 212 

oxide, 217 

salts, analytical reactions of, 
219 

sulphate, 213 
Mercury, 209 

ammoniated, 218 

ammonio-chloride, 218 

analytical reactions of, 217 

antidote to, 221 

basic sulphate, 212 

bichloride. 214 

black oxide, 217 

chlorides, 213 

copper test for, 217 

derivation of word, 39 

detection of, in organic mix- 
tures. 561 

formula of molecule, 209 

fulminate, 237 

galvanic test for, 220 

iodides, 210, et seq. 

magpie test for, 221 

medicinal compounds of, 209 

molecular weight of, 209 

native sulphide, 209 

nitrates, 212 

nomenclature of salts, 209 

oleate, 440 



INDEX. 



725 



Mercury, oxides, 210, 216, 217 

oxj'uitrates, 212 

oxysulphate, 213 

percbloride, see Mercuric chlo- 
ride. 

persulphate, see Mercuric sul- 
phate. 

plaster, 210 

quantitative determinatiou of, 
654 

red iodide, 211 
oxide. 216 
sulphide, 219 

subchloride, see Mercurous 
chloride. 

sulphate, 212 

sulphide, 209, 219 

yellow oxide, 216 
Mesitylene, 406 
Mesoxalic acid, 463 
Meta, meanings of, etc., 73, 410 
Metabisulphites, 289 
Metaborate, barium, 320 

calcium, 320 

silver, 320 

sodium, 320 
Metaboric acid, 318 
Metachloral, 451 
Metacinnamein, 460 
Metacopaivic acid, 477 
Meta-dihydroxybenzene, 436 
Metagummate calcium, 494 
Metaldehyde, 449 
Metallic elements, 20 

quantitative determination of, 
638 

radical, 65 

radicals, 71 
Metals, 19 

table of the fusibility of, 
597 
Metamerides, 380 
Metamerism, 380 
Metamers, 380 
Metantimonate. sodium, 189 
Metantimonic acid, 188 
Metantimonite, sodium, 190 
Meta-phenylene-diamine, 511 
Metaphosphate, silver, 333 
Metaphosphates, 333 
Metaphosphoric acid, 312, 314, 333, 

337 
Metaphthalic acid, 462 
Metarsenites, 174, 183 
Metastannate, sodium, 195 
Metastannic acid, 195 
Metastyrol, 460 
Metathesis, 73 
Meta-thiantimonite, sodium, 190 



Meta-thiarsenites, 183 
Metavanadates, 318 
Methane, 376, 385 

series, 376 

substitution products of, 395 
Methenyl chloride, 396 
Methoxy catechol, 321 
Meihyl alcohol, 418 

detected in presence of 

ethyl alcohol, 419 
oxidation of, 325 
Methylal, 450 
Methylamine, 509 
Methylated spirit, 419 
Methyl-arbutin, 498 

-arsonic acid, 323 

-benzene, 406, 408 

bromide, 398 

-carbinol, 419 

chloride, 398 

-couiine, 533 

cupreine, 523 

-ethyl, 386 

amylamine, 509 
propyl-isobutyl chloride, 
509 

formic acid, 448 

glycocoll, 510 

group, 409 

hydride, 385 

hydroxide, 418 

iodide, 398 

-morphine, 516 

nonyl-ketone, 464, 470 

-protocatechuic aldehyde, 459 

pyridine, 512 

salicylas, 458 

salicylate, 458 

-theobromine, 530, 539 
Methylene blue, 556 

chloride, 396 
MeihyWiioninve hydrochloridum, 556 
Methylthionine hydrochloride, 556 
Metre, 40 

relation of, to inches, 42 
Metric system, 40 

weights and measures of, 43 
MeHW, 479 

Mexican male jalap, 501 
Mezereon, 476 
Mezeremn, 476, 499 
Mica, 146 

Mk'OCOccHS nreo?, 574 
Microcosm ic salt, 357 
Microscopic examination of urinary 

sediments, 583 
Microscopv of starches, 489 
Milk, 544," 545 

-lH)ison, 511. 570 



■26 



INDEX. 



Milk-curdling ferment, 544 

of sulphur, 285 

sugar, 486 
Millon's reaction, 548 

reagent, 548 
Mimetesite, 318 
Mimotauuic acid, 342 
Mineral acid, detection of, in or- 
ganic mixtures, 563 
Mineral chameleon, 139 

Ethiop's, 219 

kermes, 189 

purple, 552 

rouge, 158, 553 

turpeth, 213 

salts, general analysis of, 354, 
et seq. 
Minerals, special, analysis of, G81 
Minium, 222 
Mint, 469 

oil, 469 
Mirbane, essence of, 407 
Mishmi bitter, 530 
Mispickel, 173 
Mishira ferri composita, 153 
Mitigated silver nitrate, 236 
Mixed ethers, 432 
Mixture, definition of, 50 

difierent from chemical combi- 
nation, 37, 50 
Mixtures, 592 
Moist sugar, 484 
Moisture in iodine, determination 

of, 660 
Molasses, 485 
Molecular, arsenic, 173 

formula, 60, 608 

mercury, 209 

phosphorus, 313 

sulphur, 285 

weight necessary in assigning 
molecular formula, 60 

weights, 54 
Molecules. 53, et seq. 
Molybdate, ammonium, 316 
Molybdates, 316 
Molybdenum, 316, 682 

sulphide, 316 
Moh'bdic anhydride, 316 

oxide, 316 
Monamines, 509 
Monarda punctata. 470 
Monobasic acids, 66, 251, 448 
Monobrom-acetanilide, 408 
Monol)ron)ated-camphor, 472 
Monobromobenzene, 407 
Monochlorobenzene, 407 
Monochloromethane. 396 
Mononchlorotoluene, 409 



Monoformin, 426 

Monohydroxyl derivatives of hy- 
drocarbons, 417 
Mononitrocellulin, 495 
Mauopersulphate, silver, 296 
Monopersulphuric acid, 296 
Monosulphide, carbon, 302 
Monoxide, carbon, 302, see also Car- 
bonic oxide 
Monoxynapthalenes, 411 
Moonseed, Canadian, 530 
Morbid urine, 575 
Mordants, 148 
Morphina, 514 
Morpliinx acetas, 514 

hydrochloriduni, 513 

sidphas. 514 
Morphine, or morphia, 513, 541 

acetate, 282, 514 

analytical reactions of, 514 

distinction from brucine, 525 

hj'drochloride, 513 

in organic mixtures, detection 
of, 566 

meconate, 513 

sulphate, 513, 514 

tartrate, 514 
Morrhuine, 443 
Mortar 338 
Mosaic gold, 196, 
Moschns, 547 

moschiferus, 547 
Moss, Carrageen, 494 

Ceylon, 494 

Chinese, 494 

Iceland, 323, 491 

Irish, 494 
Mottled soap, 441 
Moulded silver nitrate, 235 
Mountain-blue, 553 

limestone, 123 
Mucic acid, 446, 486 
Mucilage of bael, 495 

gum acacia, 121 

linseed, 494 

marshmallow, 494 

squill, 495 

starch, 488 

tragacauth, 121 
MncUago acacise, 121 

tragacanthx, 121 
Mucus in urine, 588 
Mudar, 507 
Mulberry calculus, 589, 591 

essence. 405 

juice, 552 

sugar in, 482 
Mulder's process for determination 
of alcohol, 679 



INDEX. 



727 



Multiple proportions, law of, 51, 

275, 296 
Miirex, 346 
Murexid, 346 
Muriates, see Chlorides. 
Muscarine, 511 
Musk, 547 

artificial, 547 

-deer, 547 
Mustard, 427 

artificial oil of, 427 

black, 427 

essential oil of, 427, 470 

fixed oil of, 444 

Indian, 427 

"plaster," 427 

white, 427 
Mycoderma aceti, 281, 449 
Mydriatics (table), 541 
Mylahris cichoni, 473 

phalerata, 473 . 
Myopsin, 549 
^Myotics (table), 541 
Myrcia acris, 422, 469 

oil, 469 
Myrioetin, 551 
Myricyl alcohol, 426 
Myristate, glyceryl, 442 
Myristic acid, 442, 455 
Myristicene, 469 
Myristicin, 469 
Myristicol, 469 
Myristin, 442 
Myrobalans, 340 

chebulic, 340 
Myronate, potassium, 427 
Myrosin, 427 
Myroxylon Pereirse, 460 

toiuifera, 460 
Myrrh, 479 
Myrrha, 479 
Myrrhic acid, 479 
Myrtle oil, 470 
Myrtus commnms, 470 
"mystery gold," 197 
Mytiloxine, 511 

Napelline, 526 

Naphthalene, 411, 512 

benzoic acid from, 321 
series of hydrocarbons, 411 

Naphthalenum, 411 

Naphthalic acid, 321 

a-Naphthol, 335, 411 

|3 — , 411 

Naphlhols, 411 

Naphthyl alcohols, 411 

n-Naphthylamino, 335 

Narceine, 513, 517, 541 



Narcotine, 513, 517, 541 

hydrochloride, 517 
Narthex, see Ferula. 
Nascent atoms, 69 

chlorine, 69 

hydrogen, 69 

oxygen, 69 
Natal aloes, 413 
Nataloin, 413 
Natrium, 39 
Natron, 39, 272 
Nectandra Rodisei, 529 
Nectandrine, 529 

sulphate, 529 
Needle iron ore, 149 
Neem, 507 
Negative pole, 67 
Neodymium, 171, 682 
Neon, 32, 33 
Neroli oil, 467 
Nessler test, 219, 616 
Neuridine, 511 
Neurine, 511 
Neutral salts, 66 
Neutralization, 99 
Nickar nuts, 507 
Nickel, 143 

analytical reactions of, 143 

arsenio-sulphide, 143 

cyanide, 144 

derivation of word, 39 

hydroxide, 144 

separation of, from cobalt, 142 

silver, 143 

sulphide, 143 
Nickelic hydroxide, 144 
Nicotiana tahacum, 536 
Nicotine, nicotia, or nicotina, 536 

citrate, 536 

malate, 536 
Nihilnm album, 136 
Niobium, 682 
Nitrate, ammonium, 97, 271, 273 

barium, 109 

bismuth, 228 

cobalt, 142 

cupric, 206 

ferric, 162 

lead, 224 

mercuric, 212 

mercnrous, 212 

nickel, 143 

l)ilocarpine, 537 

l>otassium. 78, 271 

silver, 234, 235 

ammonium, 237 
standard solution of, 624 

sodium, S(), '271 

strontium, 111 



728 



INDEX. 



Nitrates, 270 

aualytical reactions of, 274 
quautitative determination of, 
661, et seq. 
Nitre, 272 
chili, 271 
cubic, 271 
prismatic, 271 

sweet spirit of, 334, 401, 403 
Nitric acid, 270, 272 

anliydrous, 273 
antidotes to, 276 
dilute, 272 
fuming, 272 

in organic mixtures, detec- 
tion of, 563 
volumetric determination 
of, 623 
anhydride, 273, 275 
oxide, 274 
Nitrification, 271 
Nitrifying ferment, 271 
Nitriles, 447 
Nitrite, ammonium, 334 
amylis, 334, 405 
ethyl, 334, 401 
potassium, 334 
sodium, 334 
Nitrites, 334 

analytical reactions of, 334 
in water, test for, 334 
Nitrobenzene, 407, 498 
Nitrobenzol, 407 

in oil of bitter almonds, test 
for, 498 
Nitrocellulin, 495 
Nitro-compounds, 403 
Nitroethane, 403 
Nitrogen, 31 

derivation of word, 39 
free and combined, 33 
iodide, 219, 260 
in the atmosphere, 31 
oxides, 275 

peroxide, 270, 274, 275 
preparation of, 31, 167 
properties of, 32 
quantitative determination of, 
in organic compounds, 673, 
et seq. 
relative weight of, 32 
Nitroglycerine, 438 
Nitrohydrochloric acid, 203, 273 
Nitromannite, 445 
Nitrometer, 334 
Nitro-napthalene. 335 
Nitropentane, 403. 405 
Nitrosulphonic acid. 291 
Nitrosyl chloride, 273 



I Nitrous acid, 275, 334 

determination of, in sul- 
phuric acid, 335 

anhydride, 274, 275 

ether, 334, 401, 403 

oxide, 97, 275 
Nomenclature :— 

alkaloids, 513 

anhydrides, 91 

anhydrous salts, 90 

-ate, 77, 81 

carbonization, evaporation, ig- 
nition, incineration, 107 

double salts, 94 

ferments and fermentation, 421 

glucosides, 496 

hydrous salts, 90 

-ic, 77, 81, 151 

ide, -ite, 81 

iron salts, 151 

mercury compounds, 210 

notes on, 77, 81, 107, 496, 513 

-ol, 437 

-ous, 81, 151 
Nonane, 386 
Non-drying oils, 444 
Non-metallic elements, 20 
Non-metals, 19 

Nordhausen sulphuric acid, 293 
Normal butane, 386 

paraffins, 381 

potassium chromate, 167 

propvl iodide, 383 

salts,' 66 

solutions, 611 
a-Normal-propyl-piperidine, 533 
Notation, 58 

of organic compounds, 375 
Notes, analytical, 246, 350 
Nucleins, 543 
Nucleo-proteid, iron-containing, 

543 
Nucleo-proteids, 546 
Nuggets, gold, 197 
Numerical and Physical Matters, 40 
Nutmeg, expressed oil of, 442 

oil of, 469 
Nux-vomica, 502, 523 
seeds, 523 

Oak-bark, 341 

Oatmeal, 488 
Occlusion, 200, 201 
Ochre, 551 

bismuth. 227 

burnt, 552 

red. 552 
Octahedral sulphur, 285 
Octahedron, 178 



INDEX. 



729 



Octane, 386 

G^uauthylate ethyl, 405 

CKuanthylic acid, 455 

Oiticial liquids, specific gravities of, 

600 
Oil, ajowan, 466 

ajwain, 466 

almoud, 444 

amber, 339 

Americau pennyroyal, 469 

anise, 466 

apple, 405 

aracliis, 444 

bay, 469 

bayberry, 469 

benne, 444 

bergamot, 466 

betula, 466 

birch, 458 

bitter-almond, 323, 435, 456, 
465, 498 
artificial, 407, 498 

black sassafras, 470 

"boiled," 443 

boldo, 467 

bone, 511 

buchu, 467 

cacao, 442 

cade, 478 

cajuput, 467 

-cake, 443 

camphor, 472 

Cannabis indica, 467, 474 

caraway, 467 

cardamoms, 467 

cascarilla, 467 

cassia, 467 

castor, 444 

cedra, 467 

chamomile, 466 

chaulmoogra, 444 

cinnamon, 467 

citron, 466 

citronella, 468 

cloves, 467 

cocoa-nut, 442 

cod -liver, 443 

copaiba, 468 

coriander, 468 

cotton-seed, 439 

cowbane, 468 

croton, 444 

cubebs, 468 

cummin, 468 

dill, 466 

earth-nut, 444 

egg, 543 

elder-flowers, 470 

elecampane, 468 



Oil, erigeron, 468 
ethereal, 432 
eucalyptus, 415, 468 
fennel, 468 
fir wool, 416 
garcinia, 443 
garlic, 427 
-gas, 373 
gaultheria, 442 
geranium, 468 
gingelly, 444 
ginger, 468 

-grass, 468, 469 
grains of paradise, 469 
grass, 468, 469, 470 
ground-nut, 444 
gynocardia, 444 
hedeoma, 469 
hop, 478 

horseradish, 466 
Indian hemp, 474 
jaborandi, 537 
juniper, 469 
lard, 442 
lavender flowers, 469 

foreign, 468 
lemon, 466 

-grass. 466 
lime, 466 
linseed, 443 
lycopodium, 444 
mace, fixed, 442 

volatile, 469 
male-fern, 444 
mangosteen, 443 
meadow-sweet, 458, 503 
melissa, 471 
mint, 469 
mustard, artificial, 427 

essential, 427, 470 

fixed, 444 
myrcia, 469 
myrtle, 470 
neroli, 467 
nutmeg, fixed, 442 

volatile, 469 
of vitriol, 292 
olibanum, 480 
olive, 439, 444 
omum, 466 
orange-flower, 467 

-peel, 466 
orris, 469 
palm, 442 
paraftin, 388 
pea-nut, 444 
pelargonium, 469 
penny royal. 469 
pepper, 538 



'30 



INDEX. 



Oil, peppermint, 469 

petit-grain, 467 

phellandrium, 415 

pilocarpus, 537 

pimento, 467 

pine Avool. 416 

ptychotis, 466 

Pulsatilla, 469 

resin, 474 

rosemary. 470 

roses, 469 

rue, 464, 470 

sage, 470 

sandal-wood, 470 

sassafras, 470 
black, 470 

savin, 470 

sesame, 444 

shark-liver, 444 

spearmint, 469 

sperm, 426 

spike 468 

star-anise, 466 

stroplianthus, 506 

sweet -birch, 458, 466 
-flag, 470 

teal 444 

theobroma, 442 

thyme, 470 

turmeric, 471 

turpentine, 415 
rectified, 415 

valerian, 471 

verbena, 471 

water-hemlock, 468 

wine, 432 

winter-green, 458 

wood, 477 

worm-seed, 471 
Oils, analysis, 681 

and fats, composition of, 439 

drying, 443 

essential, 464, et seq. 

tested for alcohol, 465 

fixed, 443, 

non-drying, 443 

terpeneless, 465 

volatile, 464, et seq. 

process for obtaining, 465 
Ointment, see Z'^nguentum. 
Ointments, 592 
Okra, 495 

-ol, meaning of, 437 
Oleate, glvcervl, 439 

lead, 224 "^ 

mercury, 440 

potassium, 439 
sodium, 439 
veratrine, 440 



Oleate, zinc, 440 
Oleates, 439, 440 
Oleatum atropinse, 440 

cocainx, 440 

hydrargyri, 440 

qidninx, 519 

veratrinx, 440, 540 
Olefiant gas, 392 

Olefine series of hydrocarbons, 389 
Olefines, occurrences of, in nature, 
392 

production of, 392 

relation to paraflins, 389 
Oleic acid, 439, 455, 456 
Oleine, 439 
Oleoresina, aspidii. 477 

capsic'i, 477 

cubebse, All 

lupulini, 478 

piperis, 478 

singiberis, 478 
Oleoresins, 477 
Oleum aethereum, 432 

amygdalx expressum, 4AA, 

anisi, 466 

aurantii corticis, 466 

betidse, 466 

cadinuin, 478 

cajuputi, 467 

cari, 467 

caryophylU, 467 

chenopodii, All 

cinnamomi, 468 

copaibse, 468 

coriandri, 468 

ciibebx, 468 

erigerontis, 468 

eucalypti, 468 

fceniculi, 468 

garcinex purpurex, 443 

gaultherix, 458 

hedeomx, 469 

juniperi, 469 

lavandulx, 469 

limoHis, 466 

lini, 443 

menthx piperitx, 46£ 
viridis, 469 

morrhux, 443 

myristicx, 469 

olivx, 439, 444^ 

picis liqtiidx, 478 

pimenfx, 467 

pini, 416 

ricini. 444 

rosx, 469 

rosmariui, 470 

snbiux, 470 

santali, 470 



INDEX. 



731 



Oleum sassafras, 470 

sinapsis volatile, 427, 470 

terebmthinre, 41o 

rectificatiim, 415 

theobroinatis, 442 

thy mi, 470 

Hfif?w, 444 
Olibanuiu, 479 
Olive-oil, 439, 444 

test of purity, 439 
Omentum, 442 
Omum oil, 465 
Opal, 337 
Oplielic acid, 335 
Opianic acid, 517 
Opium, 513 

alkaloids, 513 

detectiou of, in organic mix- 
tures, 567, et seq. 

meconic acid, 332 
Orange-chrome, 226 

-flower oil, 467 
water, 467 

-peel oil, 466 

wine, 422 
Orchil, 554 
Orchis tuber, 495 
Orcin, 554 
Ordeal-poison, 537 
Orellin, 552 
Organic analysis, 670 
Organic bases, 508 

artificial, 508" 

chemistry, 368 

advice to students, 366 

compounds, classes of, 374 
composition of, 370 
constitution of, 374 
effects of heat, 372 
notation of, 375 
Organized urinary sediments, 583 
Orizabin, 501 
Orpiment, 173, 551 
Orris, butter of, 469 

camphor of, 469 

oil of, 469 
Ortho-, meanings of, etc., 333, 410 
Orthodihydroxy-benzene, 436 
Orthoform, 459 

Orthohydroxybenzaldchyde, 458 
Orthohj-droxybenzoic acid, 457 
Orthonitrophenylpropiolic acid, 554 
Orthophoiolsulphonic acid, 429 
Orthophosphates, 315, 333 
Orthophosphoric acid, 315, 333, 

337 
Ortbophthalic acid, 462 
Ortho-thiantimonitc, sodium, 190 
Orthovanadates, 318 



Oryza sativa, 488 

starch of, 490 (fig.) 
OryzK, farina, 488 
Osmium, 199, 201, 682 
Otto of rose, 469 
Ouabain, 502 
Ourari, 525 

Ouroiiparia gambir, 342 
-ous, meaning of, 81, 151 
Ox-bile, 549 

-gall, 549 
Oxalate, ammonium, 98 

barium, 110, 303 

calcium, 122, 303 

cerium, 172 

hydrogen, 303 

silver, 304 

sodium, 303 
Oxalates, 302 

analytical reactions of, 303 

quantitative determination of, 

me 

separation of, from phosphates 
and ferric oxide, 359 
Oxalic acid, 302, 461, 463 

antidotes to, 304 

chemically pure, 303 

in organic mixtures, detec- 
tion of, 564 
Oxamide, 461 
Oxidation, 69, 274 
Oxide, aluminium, 146, 147 
antimony, 187 
arsenic, 173, 175 
arsenous, 173 
barium, 109 
bismuth, 227 
cacodyl, 323 
cadmium, 233 
calcium, 113 

carbonic, 36, 299, 304, 305, 326 
chromic, 166 
chromous, 166 
cobalt, 141 
copper, black, 206 
cupric, 206, 208 
cuprous, 206, 483, 495 
ferric, 149, 158 
ferrous, 151 
iron, black, 150 

magnetic, 149, 150, 162 

red, 149, 158 
lead, 222 

pncc-colored, 222 

rod, 222 
magnesium, 125 
nian<>anose, 138 

black, 138, 254 
mercuric, 216 



732 



INDEX, 



Oxide, mercurous, 217 

mercury, black, 217 
red, 216 
yellow, 236 

molybdenum, 316 

nitric, 274, 275 

nitrous, 97, 275 

silicon, 338 

silver, 236 

stannic, 193, 194 

stannous, 196 

tin, 193, 194, 196 

zinc, 135 
Oxides of nitrogen, 275 

identified, 361 
Oxidizing agents, 274, 295 

flame, 136 
Oxyacan thine, 530 
Oxyacetate, copper, 206 

lead, 223 
Oxyacids of sulphur, 296 
Oxybromide, bismuth, 229 
Oxy carbonate, bismuth, 230 
Oxychloride antimony, 187, 191 

bismuth, 229, 231* 

ferric, 156 

mercuric, 276 

phosphorus, 313 
Oxychromate, lead, 226 
Oxycopaivic acid, 477 
Oxygen, 20 

allotropic form of, 261 

derivation of word, 39 

determination of, in gas mix- 
tures, 344 
in organic compounds, 783 

in the air, 24, 32 

its relation to animal and 
vegetable life, 24 

preparation of, 20, 109 

properties of, 23 

solubility in water, 24 

specific gravity of, 29 
Oxygenated water, 109 
Oxyglutaric acid, 463 
Oxyhydroxides, iron, 149, 157 
Oxyiodate, ferric, 280 
Oxyiodide, bismuth, 229 

iron, 154 
Oxymalonic acid, 463 
Oxynitrate, bismuth, 228 

mercuric, 212 
Oxysuccinic acid, 463 
Oxysulphate, bismuth, 229 

iron, 152 

mercuric, 213 
Oxysulphides, antimony, 189 
Oxytoluyltropeine, 528 
Ozokerite, 426 



Ozone, 260 

tests for, 261 
Ozonic ether, 577 
Oxonized air, 261 

Palas tree, 342 
Palladium, 201, 683 

chloride, 570 
Palm-oil, 442 
Palmitate, cetyl, 426 

glyceryl, 443 

melissyl, 426 
Palmitic acid, 442, 453 
Palmitine, 442 
Pan, 343 
Pancreatic diastase, 549 

enzymes, 549 
Pancreatine, 549 
Pancreatinumi, 549 
Papain, 549 
Papaver rhseas, 552 

somniferum, 513 
Papaverine, 517, 541 
Papaw tree, 549 
Paper, bibulous 115 

filter, 115 

litmus, blue, 99 
red, 99 

turmeric, 99 
Papers, test-, 99 

Para-, meanings of, etc., 306, 410 
Para-acetphenetidiu, 408 
Paracoto, 499 
Paracotoin, 499 
Paracyauogen, 266, 268 
Para-dihydroxvbenzene, 436 
Paradol, 469, 531 . 
ParafiSn, 388 

oil, 382, 388 

series of hydrocarbons, 376 

wax, 387, 388 
ParaflSnic acid, 388 
Parafl&ns, chlorination of, 395 

constitution of. 376, et seq. 

formation of, 381 

gaseous, 387 

general character of, 387 

halogen derivatives of, 396 

methods of preparation, 382 

monohydroxyl derivatives of, 
417 

normal, 381 

occurrence in nature, 381 

relations to olefines, 389 

solid, 388 

synthesis of, 382, et seq. 
by electrolysis, 384 
Paraffinnm, 388 

liquidum, 388 



INDEX. 



733 



Paraformaldehyde, 448 
Paraguay tea, 530 
Parahydroxybenzaldehyde, 458 
Paraldehyde, 449 
Paraldehydum, 449 
Parallin, 504 

Para-methyl-isopropylbenzene, 409 
Para-phenetol-carbamide, 408 

-phenolsul phonic acid, 434 

-phenylene-diamine, 511 
Paraphthalic acid, 462 
Paratartaric acid, 306 
Pareira,, 529 
Paricine, 529 
Parietinic acid, 412 
Parigenin, 504 
Parilla, yellow, 530 
Paris blue, 554 

red, 552 
Particles, elementary, 52 
Patent sugar, 483 
Pea-nut oil, 444 
Peach, 482 
Pear-wine, 422 
Pearl-barley, 488 

-sago starch, 490 (fig.)- 

-white, 229, 555 
Pearlash, 71 
Peas, 546 
Pectin, 494 

Pelargonate, ethyl, 405 
Pelargonic acid, 455 
Pelargonium, 469 

oil of, 469 
Pelletierinse tannas, 537 
Pelletierine, 627 

tannate, 537 
Pellitory-root, 476 
Pelosine, 529 
Pencils, "lead," 298 
Pennyroyal, American, oil of, 469 

oil of, 469 
Pennywort, Indian, 507 
Pentane, 386 

Pentahydric alcohols, 445 
Pentathionic acid, 286, 296 
Pepper, black, 538 

cayenne, 531 

cubeb, 538 

long, 538 

melegueta, 469 

oil of, 538 

oleoresin, 478 

resin of, 476 

white, 538 
Peppermint oil, 469 
Pepsinnm, 548 
Pepsin, 548 

in urine, 581 



Pepsinogen, 548 
Peptone, 549 
Peptones, 546 

in urine, 575 
Per-, meaning of, 155 
Percentage composition, 60 
Percha tree, 471 
Perchlorate, potassium, 278 
Perchloric acid, 279 
Perchloride, gold, see Auric chloride. 

iron, see Ferric chloride. 

anhydrous, see Ferric chlo- 
ride, anhydrous. 

mercury, see Mercuric chloride. 

platinum, see Platinic chloride. 

tin, see Stannic chloride. 
Perchloro-methane, 396 
Percussion caps, 237 
Perfumes, 465 
Periodic Law, 364 
Perkin's reaction, 460, 461, 554 
Permanent hardness iu water, 301 
Permanganate, potassium, 81, 139 
Permanganic acid, 141 
Pernitrate, iron, see Ferric nitrate. 
Peroxide, see also dioxide. 

barium, 109 

chlorine, 279 

lead, 224 

nitrogen, 270, 274, 275 
Perry, 422 
Persian berries, 551 
Persite, 481 
Persodine, 296 
Personne's solution, 627 
Persulphate, ammonium, 295 

barium, 295 

iron, see Ferric sulphate. 

mercury, see Mercuric sulphate. 

potassium, 295 

sodium, 296 
Persulphates, 157, 295 

analytical reactions of, 296 
Persulphuric acid, 295 

anhydride, 295 
Peru, balsam of, 323, 460 
Peruvine, 460 
Petalite, 104 
Petit grain oil, 467 
Petrolatum, 388 

album, 388 

liquidum, 388 
Petroleiue, 388 
Petroleum benzin. 387, 406 
purified, 387 

crude, 387 

ether, 387 

gas, 385 

light, 387 



734 



INDEX, 



Pcttenkofer's test for bile, 550 
Peumus holdus, 467 
Pewter, 186, 193, 222, 228 
Phseoretiue, 412 
Pharaoh's serpents, 345 
Fharhitis nil, 502 
Pharbitisin, 502 
Pharmacognosy, 18 
Pharmacology, 18 
Pharmacy, 18 
Phellandrene, 415, 467 
Phellandrium aquaticum, 415 
Phenacetin, 408 
Phenates, 434 
Phenazone, 408 
Phenic acid, 432 . 

alcohol, 432 
Phenocoll, 408 
Phenol, 432 

Uquefactum, 433 

-mercury, 434 
Phenolphthalein, 411, 462 

test solution, 624 
Phenols, 432 
Phenolsulphonate, sodium, 434 

zinc, 435 
Phenolsulphonic acid (ortho), 429 

(para), 434 
Phenylacetamide, 408 
Phenylamine, 407, 511 
Phenylcarbinol, 435 
Phenyl-dimethyl-isopyrazolone, 408 
Phenylglycollic acid, 497 
Phenyl group, 409 
Phenylhydrazine, 510 
Phenylis salicyJas, 459 
Phenylmethyl ketone, 464 
Phenyl salicylate, 459 
Phosgen, 299 
Phosphate, ammonium, 98 

magnesium, 126, 315 

separation of, from 
oxalates and ferric 
oxide, 359 

barium, 317 

hydrogen, 110 

calcium, 112, 117, 312 
acids, 315 
hydrogen, 118 

codeine, 516 

ferric, 161, 316 

ferrous, 153 

magnesium, in bones, 117 

silver, 237, 315 

sodium, 91, 118 

how prepared from calcium 
phosphate, 118 
Phosphates, 312 

analytical reactions of, 315 



Phosphates, quantitative determi- 
nation of, 6(;7 
Phosphide, hydrogen, 328 

trihydrogeu, 328, 329 
Phosphines, 509 
Phosphites, 335 

test for, 330 
Phosphoantimonic acid, 570 
Phosphomolybdic acid, 316, 570 
Phosphoric acid, 31, 312, 333 
diluted, 31, 313 
glacial, 314 

quantitative determina- 
tion of free, 667 

anhydride, 31, 314, 333 
Phosphorized fats, 543 
Phosphorous acid, 256, 335, 337 

oxide, 335 
Phosphorus, 30, 312 

acids of, 336 

bromide, 256, 314 

combustion of, 30 

derivation of word, 39 

detection of, in organic mix- 
tures, 565 

granulated, 312 

molecular formula of, 313 

oxychloride, 313 

pentachloride, 313 

pill, 312 

properties of, 30, 312 

red or amorphous, 30, 313 

trichloride, 282, 313 

tri-iodide, 397 
Phosphotungstic acid, 570 
Phosphuretfed hydrogen, 328, 329 
Photographic hypo-eliminator, 296 

" reducer," 296 

use of '• hypo," 295 
Phthaleins, 411 
Phthalic acid, 322, 411, 462 

anhydride, 411, 462 

series of acids, 462 
Pliyllocyanin, 554 
Phylloxauthin, 554 
Physical changes, 49 

examination of urine, 574 
Physostigma, 537 

venenosum, 537 
Physostigminx salicylas, 537 

sulphas, 537 
Physostigmine, 537 
Phytolacca. 507 
Phytolaccin, 507 
Picea exxelsa, 476 
Picoline, 511 
Picric acid, 435, 518, 552 
Picrorhiza kurroa, 502 
Picrorhizetin, 502 



A 



INDEX. 



735 



Picroihiziu, 502 

Picrosclerotine, 476 

Picrotin, 503 

Picrotoxiu, 503, 541 

Picrotoxinin, 503 

Pig-iron, 150 

Pigments, 554 

Pigmentum nigrum, 555 

Pill, see Pilulae. 

Pills, 592 

Pilocarpidiue, 537 

PUocarpinx hydrochloridum, 537 

nitras, 537 
Pilocarpine, 537 

hydrochloride, 537 
Pilocarpus, 537 

Jaborandi, 537 
Pilul'cC aloes et ferri, 152 

ferri carbonatis, 153 
iodidi, 155 

phosphori, 312 
Pimaric acid, 442, 474 
Pimento oil, 467 
Pimpinella anisum, 466 
Pine-apple, essence of, 405 

wool, 416 
oil, 416 
Pinene, 415 
Piuic acid, 442, 474 
Pink saucers, 553 

the common, 504 
Pins, 193 
Pinus, 415, 416, 474 

Abies, 415, 474 

australis, 415 

larix, 342, 415 

Ledebourii, 416 

maritima, 415 

palustris, 478 

picea, 415 

pinaster, 415 

Pumilio, 416 

sylvestris, 416 

txda, 415 
Pipe-clay, 147 
Piper, 538 

Betle, 343 
Piperazine, 509 
Piperic acid, 538 
Piperidine, 476, 538 

acid tartrate, 538 
Piperina, 538 
Piperine, 538 
Pipette, 258 

Pistachia terebinthus, 415 
Pitch, 478 

Burgundy, 476 
Pituri, 537 
Piuri, 551 



8ee 
Chloroplat- 
inates. 



39 



Pix liquida, 416, 476 
Plant alkaloids, 510 
Plants and animals, complementary 

action of, on air, 24 
Plaster lead, 225 
mercurial, 210 
of Paris, 112, 555 
Plasters, 592 
Plastic sulphur, 285 
Plate, tin-, 193 
Platinic chloride, 200, 570 
test solution, 200 
sulphide, 200 
Platinized asbestos, 291 
Platinous chloride, 201 
Platinum, 199 

analytical reactions of, 210 
and ammonium ] 

chloride 
and lithium 

chloride 
and potassium 

chloride 
and sodium 

chloride 
black. 200 
chloride, 200 
derivation of word, 
foil, 199 

perchloride, see Platinic chlo- 
ride. 
residues, to recover, 201 
spongy, 201 
Pleurisy root, 507 
Plum, 482 
Plumbago, 36, 298 
Plumbi acetas, 223 
empla strum, 225 
iodidnm, 224 
nitras, 224 
oxidum, 222 
subacetatis, liquor, 223 
Plumbic acetate, sulphate, etc, see 

Lead. 
Plumbum, 38 
Pocula emetica, 186 
Podophyllotoxin, 476 
Podophyllum, 476 
peitatum, 476 
resin, 476 
Poison ivy, 343 

oak, 343 
Poisonous alkaloids, Stas's process 
for detection of, in or- 
ganic material, 568 ■ 
Sonnenschein's process, 569 
Poisons, antidotes to, a-cc Antidotes, 
detection of in organic mix- 
tures, 560, et scq. 



736 



INDEX. 



Poisons, of cheese, milk, fish, etc. 

511, 750 
Poke root, 507 
Polybasic acids, 66, 463 
Polychroite, 503, 551 
Polygala senega, 505 
Polygalic acid, 505 
Polyhydric alcohols, 445 
Polymerides, 380 
Polymer ism, 380 
Polymers, 380 
Polysulphide, calcium, 286 
Pomegranate rind, 342 

-root bark, 342 
Poppy capsules, 513 

white, 513 
Populus, 503 
Porcelain 338 
Porridge, 488 
Port wine, 422 
Porter, 422 
Portland cement, 338 
Positive pole, 67 
Potash, acetate 1 

alum, 

bicarbonate 

bitartrate 

carbonate 

chlorate 

citrate 

dichromate 

iodate 

nitrate 

permanganate 

prussiate red 
yellow 

sulphate 

tartrate 
acid 

bulbs, 784 

caustic, 72 

solution of, 72 
volumetric determination 
of solutions of, 618 

sulphurated, 73 

water, 299 
Potashes, 71 

preparation of, 
ashes, 71 
Potassii acetas, 75 

bicarbonas, 76 

bitartras, 71, 84, 305 

bromidum, 81 

carbonas, 72 

chloras, 277 

citras, 78 

effervescens, 78 

cyanidum, 266 

dichromas, 167 



Old names 
for potassium 
salts, which 
see. 



from wood 



] Potassii et sodii tartras, 79, 84, 305 
ferrocyanidum, 266, 326 
hydroxidum, 72 
hypophosphis, 329 
iodidnm, 80 
nitras, 78 

permanganas, 82, 139 
sulphasl 78, 272 
Potassium, 71, 72 
acetate, 74 , 283 
acid carbonate, 76 

oxalate, 303 

succinate, 340 

sulphate, 272 

sulphite, 288 

tartrate, 88, 305 
alizarate, 411 
aluminium sulphate, 146 
analytical reactions of, 82 
and bismuth iodide, 570 

cadmium iodide, 570 

diazobenzene hydroxide, 
571 

platinum chloride see po- 
tassium, chloroplatiti- 
nate. 

sodium, tartrate, 79, 84, 206, 
305 
angelate, 466 
anhydrochromate, 167 
antimonyl tartrate, 188 
benzoate, 460 
bicarbonate, 76 
bismuth, thiosulphate, 83 
bitartrale, 83 
borotartrate, 319 
bromate, 81 
bromide, 81, 257 
carbolate, 433 
carbonate, 72, 82 

volumetric determination 
of, 618 
Carnot's test of, 83 
chlorate, 20, 277 
chloride, 71, 82 
chloroplatinate, 82, 83, 201 
chromate, 167 
cinnamate, 460 
citrate, 77 
cobalticyanide, 142 
cobaUic nitrite, 85, 142 
cyanate, 266, 324 
cyanide, 266 
derivation of word, 39 
dichromate. 167 
ferricyanide, 326 

test solution, 327 
ferrocyanide, 266, 326 

test solution, 326 



INDEX. 



71 



Potassium, ferrous ferrocyanide, 
267 
-flame, 84, 106 
formate, 401 
hydrogen carbonate, 76 

sulphate, 272 

tai-trate, 83 
hydrolulphide, 287 
hydroxide, 72 

impurities in commercial, 
72 

volumetric determination 
of, 618 
iodate, 79, 280 
iodide, 79, 260 
manganate, 81, 139 
mercuric iodide, 211, 220 
meta-bisulphite, 289 
myronate, 427 
nickel cyanide, 144 
nitrate, 78, 271 
nitrite, 334 
occurrence, 71 
oleate, 439 
perchlorate, 278 
permanganate, 81, 139 

volumetric determination 
of, 634 
persulphate, 295 
phenol, 432 
preparation of, 71 
properties of, 72 
prussiate red. 326 

yellow, 266, 326 
quantitative determination of, 

638 
red pruss.ato, "26 
salts, analogy of, to sodium 

salts, 92 
sodium, ammonium, and lith- 
ium, seviaratic n of, 105 
sources, 71 
star.nate, 195 
Slice '■■■;. 3'iO 
sulpliamidobenzoate, 429 
sulphate, 77, 272 
sulphides, 73, 287 
tartrate, 78, 306 

acid, 78, 83, 305 
^ thiocyauate, 344 
yellow prussiate, 266, 326 
zincate, 137 
Potato, 538 

-oil, 425 

-starch, 487, 490 (fig.). 
Powder, see Piilvis. 
bleaching, 119 
compound eftcrvescing. 306 
gray, 210 • 

47 



Powder, putty, 195 

Tripoli, 337 
Powders, 592 

specific gravities of, 603 
Praseodymium, 171, 683 
Precipitant, 83 
Precipitate, 82, 83 

red, 216 

white, 218, 255 
fusible, 218 
infusible, 219 
Precipitated calcium carbonate, 115 

sulphur, 285 

calcareous, 286 
Precipitates soluble in solution . oi' 
salts, 246 

to wash, 115 

to weigh, 640 
Precipitation, 82 

fractional, 362 
Precipitatum per se, 216 
Prepared calamine, 134 

chalk, 117 

suet, 442 
Prepare-liquor, tiu, 195 
Pressure, correction of volume of 
gas for, 47, 605 

-gauges, 45 

standard, 47 
Prickly ash, 530 
Primary alcohols, 417 

amines, 508 
Principles, 49, et seq. 
Printer's ink, 555 
Prismatic nitre, 271 

sulphur, 285 
1^1 uuf spirit, 423 
Propane, 383, 386 
Propanetricarboxylic acid, 462 
Propenyi, 437 

alcohol, 437 
Propeptone, 575 
Prophetin, 500 
Propione, 464 
Propionic acid, 453 
Proportions, atomic, 53, 210 

constant, 51 

multiple, 51. 275 
Propyl alcohol, 424 
Propvlamine, 509 
Propylene, 389, 392 
Propylforniic acid, 453 
Propyl iodide, normal, 383 

iso-, 383 
Proteid principles, 542 
Proteids, detection of, in urine, .'T.^ 

mean composition. 546 
Proteolytic enzyme, 549 
Protocatechuic acid, 518 



INDEX. 



i :> ocatecbuic aldehyde, 459 
>■ ■jiococcHs vulgaris, 445 
*' opine. 517, 538 
overatridiii, 536 
overatrine, 536 
, ■ iimate analysis, 670 
": ..lie, 484 
rrh niin, 484 
i' lus serotina, 498 
rirginiana, 498 
T ; : ssian blue, 165, 265, 269, 326, 554 
i ' 5siate of potash, red, 326 

yellow, 265, 326 
J': 5sic acid, 265 

antidotes, 270 
■>v''idoacouitine, 526, 527 
' -' adohyoscyamine, 536 
iV idoiuulin, 491 
}'.■ adojerviue, 536 
rv udomorphine, 517 
j'-udoxan thine, 510 
rocarpin, 552 
rocarpus erinaceus, 342 
marstqnum, 342 
santalinus, 470, 552 
maiues. 511, 570 
alin, 489 
, ' zhotis ajowan, 466 

oil, 466 
• ■ i Idling, iron, 150 
; Jegone, 469 
} < saUIla, 469 

oil, 469 
Ptii vis Algarothi, 187 
angelicus, 187 
effervescpns comjmftitiis. 306 
ipecacuanlics et opil, 534 
= 'jjnice-stone, 337 
!■ ■ lica granatum, 342, 536 
"• 'uicine, 536 
• rified ox-gall, 549 
. rple of Cassius, 199, 553 
dye, 346 

foxglove, active principle in, 
499 
rpurin, 582 
rree, 551 
' s in urine, 587 

sch's test for tartaric acid in ci- 
ric acid, 311 
trescine, 511 
! tty-povs'der, 195 
■ rethric acid, 477 
rethriii, 476, 538 
' rethrnm, 476 
carneum, All 
ciner arise folium, 477 
rosenih, 477 
uridine, 512 



Pyridine bases, 512 
/3-pyridyl-a-lactic acid, 538 
Pyrites, copper, 205 

iron, 149 
Pyroarsenate, sodium, 176 
Pyroarsenates, 174 
Pyroborate, sodium, 318 
Pyrocatechin, 436 
Pyrogallic acid, 343, 445, 459 

use of, in gas analysis, 344 
Pyrogallol, 343, 445,^459 
Pyroligneous acid, 281 
Pyrolusite, 138 
Pyromellitic acid, 463 
Pj^rometers, 597 
Pyromorphite, 318 
Pyrophorus, 163 
Pyrophosphate, iron, 161, 336 

silver, 336 

sodium, 336 
Pyrophosphates, 336 

analytical reactions of, 337 
Pyrophosp boric acid, 314, 336 
Pyrosulphuric acid, 292, 293 
Pyrovanadates. 318 
Pyroxylic spirit, 418 
Pyroxylin, 495 
Pyroxylinum, 495 
Pyrrol, 511 
Pyrus Cydonia, 495 

QUADRIVALENCE, 63 

Qualitative analysis, 105, 349, 556 
Quantitative analysis, 609, et seq. 
Quantivalence, 63 

of acid radicals, 63, '-"i 

variation in, 150-1 "'S -17 
Quartz, 337 
Quassia, 503 
Quassin, 503 
Quebrachine, 527 
Quebracho bark, 527 
Quebracho bianco, 527 

Colorado, 527 
Queen's root, 539 
Quercite, 445 
Quercitrin, 551 
Quercitron, 551 
Quercus tinctoria, 551 
Quevenne's iron, 463 
Quicklime, 113 
Quillaic acid, 505 
Quillaja, 505 

saponaria, 505 
Qu in amine, 523 
Qui nates, 518 
Quince, essence, 405 

seeds, 495 
Quiuia, see Quinine. 



INDEX. 



739 



Quiuic acid, 518 
Quiuicine, 523 
Quiuidine, 521 

hydriodide, 521 

sulphate, 521 

tartrate, 521 
Qtdnina, 518 
Qdninse, bisulpJias, 518 

hydrobromidum, 519 

hydrochloridum, 519 

salicylas, 519 

sulphas, 518 
Quinine, 518, 541 

acid hydrochloride, 519 

amorphous, 522 

and iron citrate, soluble, 160, 
519 

bisulphate, 519 

hydrobromide, 519 

hydrochloride, 519 

hypophosphite, 329 

iodo-sulphate, 520 

kinate, 518 

neutral sulphate, 519 

oxalate, 519 

quinate, 518 

reactions of, 519 

salicylate, 519 

sulphate, 518 
Qainiretin, 523 
(^uinoidine, 522 
Quinoline, 512 
Quinone, 498, 518 

Racemic acid, 306 
Eadical, 63 

acid, 65 

metallic, 65 
Radicals; acid, 63, 65, 251 

metallic. 65, 71 
Radium, 683 
Rai, 427 

Raisins, 305, 482 
Ranunculus, 469 
Raspberry, sugar in, 482 
Ratafia, 422 
Rattan j)alm, 475 
Ratti, 501 
Reaction, acid, 65 

alkaline, 64 
Reactions, analytical, 70 

synthetical, 70 
Reagents for alkaloids, 570 

list of, XV. 
Realgar, 173 
Receiver, 131 
Rectification, 131 
Rectified oil of turpentine, 415 

spirit, 131 



Red, Chinese, 552 

chrome, 552 

cinchona, 518 

coloring matters, 552 

corpuscles in blood, 544 

earth, 552 

enamel colors, 553 

gravel, 582 

gum, 468 

haematite, 149 

iodide, mercury, 211 

lead, 222, 552 

litmus paper, 99 

ochre, 552 

oxide, iron, 158, 552 
mercuric, 216 

Paris, 552 

phosphorus, 313 

-poppy petals, 552 

precipitate, 216 

prussiate of potash, 327 

-rose petals, 552 

sandal-wood, 470, 552 

saunders, 470, 552 

sulphide, mercuric, 219 

Venetian, 158 
Reduced indigo, 553 

iron, 162 
" Reducer," photographic, 296 
Reducing flame, 136 
Reduction, 69 

Reinsch's test for arsenic, 178 
Relative density, see Specific Grav- 
ity. 

weight of hydrogen and oxy- 
gen, 29 
Remijia bark, 518 
Rennet, 544 

extract, 544 
Rennin, 544 
Reseda luteola, 552 
Residues, platinum, 201 
Resin, 415, 474 

arnica, 474 

cannabis, 474 

capsicum, 475 

castor, 475 

copal, 475 

ergot, 475 

guaiacum, 476, 501 

Indian hemp, 474 

jalap, 476, 501 

kaladana, 502 

kamala, 477 

kousso, 476 

mastic, 476 

mezercon, 476 

oils, 474 

pepper, 476 



'40 



INDEX. 



Resin, podophyllum, 476 

pyrethrum, 476 

rottlera, 477 

scammouT, 480, 505 

soap, 442 
Eesina, 474 

jalap ce, 502 

podophyUi. 476 

scammonii. 505 
Eesins, 464, 473 
Resorcinol, 436 
Eetort. 130 
Rhamni succus, 498 
Ehamuiu, 551 
Ehamnose. 500 
Rhamnus catharticus, 554 

frangida. 500 

purshiana, 412 
Ehapouticin, 412 
Ehatauy root, 342 
Eheic acid. 412 
Ehein. 412 
Rheum, 412 
Eheumiu. 412 
Ehodium, 201. 683 
Ehceadine, 517 
Ehubarb, 302, 412. 476, 551 

calcium oxalate from, 303 

resins of, 477 

root. 412 
Ehubarbaric acid, 412 
Ehubarbariu, 412 
Rhus cotinus, 551 

glabra, 343 
Eice. 488 

-starch. 489, 490 (fig.) 
Eicin, 445 
Eiciuiue, 445 
Eiciuoleate. glyceryl. 444 
Eiciuoleiue. 444 
Eingworm powder. 412 
Roccella tinctoria, 415 
Eoche alum, 147 
Eochelle salt. 79, 84, 305, 306 
Eock alum, 147 

salt, 86, 252 
Eohuu bark, 507 
Eoll sulphur, 284 
Eoman cement. 338 
Rosa canina, 459 

gallica, 552 
Eose, 552 

-oil, 469 

-petals, 552 
Eosaniline, 408. 555 
Eosemarv-oil, 545 
Eosin. 415. 474 
Eotang i)alm, 477 
Eotten-stone. 146 



Rottlera tinctoria, 477 

Eottlerin, 477 

Eouge, animal, 323, 553 

face, 323 

mineral, 158, 553 

vegetable, 553 
Riibia tinctoria, 552 
Eubiauic acid, 552 
Eubidium, 683 
Eubijervine, 536 
Rubus. 343 
Eubv. 146 
Eue-oil, 464, 470 
Eum, 422 
Eumex. 412 
Eumicin, 412 
Eupi. 526 
Eus. 540 
Eust. iron, 150 
Eutate. glyceryl, 443 
Ruthenium, 201, 683 
Eutic acid, 442 

Sabadillixe, 540 
8abadine. 540 
Sabadinine, 540 
Sabatrine, 540 
Sabinol, 470 
Sabinyl, acetate, 470 
Saccharated ferrous carbonate, 152 
volumetric determina- 
tion of, 632 
Saccharic acid, 445, 486 
Saccharimetry, 673 
Saccharin, 428 

soluble, 429 
Saccharine, 483 
Saccharometer, 601, 678 
Saccharomyces, 486 

cerevisiee, 420 
Saccharoses, 484 
Saccharum, 484 

Inctis, 486 

Hstum, 485 
Sacred bark, 412 
Safety-lamp, 29 
Safiiower. 553 
Satfron, 551 

bastard. 553 

dver's, 553 
Safrol, 470 
Safrolum, 470 
Sage, oil of, 470 
Sago, 488 

palm, 488 

starch, 490 (fig.) 
Saint Ignatius's bean, 523 
Sal ammoniac, 94 

prnnella, 272 



INDEX. 



741 



Sal volatile, 97 
Salep, 495 

Salicin, 437, 458, 503 
Salicinum, 503 
Salicyl alcohol, 437 

aldehyde, 437, 457 

hydride, 458 
Salicylate, ammonium, 457 

bismuth, 230 

lithium, 104 

methyl, 458 

phenyl, 459 

quinine, 519 

sodium, 457 

strontium, 111 
Salicylic acid, 439, 457 
Salicylol, 458 
Salicylous acid, 458 
Saligenin, 437, 503 
Saligenol, 437, 503 
Saliretin, 503 
Saliva, 345 
Salix, 503 
Salol, 459 
Salseparin, 504 
Salt-cake, 89- 

common, 86, 252 

Epsom, 123, 290 

Glauber's, 253 

microcosmic, 356 

of sorrel, 303 

Eochelle, 79, 93, 305, 306 

rock, 86, 252 
Saltpetre, 272 

Chili, 271 
Salts, 64, 65 

acid, m, 77, 79 

action of blowpipe on, 356 
of heat on, 355 
of sulphuric acid on, 356 

alkyl, 447 

ammonium, volatility of, 103 

analogies of, 92 

analysis of insoluble, 360 

anhydrous, 90 

basic, (^^ 

bleaching, 277 

constitution of, 65, 251 

double, 94, 146 

formation of, 75 

haloid, 265 

hydrous, 90 

iron, nomenclature of, 151 

neutral, 66 

nomenclature of, 77, 81 

normal, 66 

physical properties of, 355 

substitution of, for each other, 
92 



Salts, table of the solubility or in- 
solubility of, in water, 351 
Sand, 337 

-bath, 35 

-stone, 337 

-tray, 35 
Sandal- wood, oil of, 470 

red, 470, 552, 

white, 470 

yellow, 470 
Saunders-wood, red, 470, 552 
Sandstone, 337 
Sanguinaria, 538 

canadensis, 538 
Sanguiuarine, 538 
Santalal, 470 
Santalin, 552 
Santalum album, 470 

rubrum, 552 
Santonic acid, 504 
Santonica, 504 
Santonin, 504 
Santoniniim, 504 
Santoniretin, 504 
Sap-green, 554 
Sapo, 441 

icalinus venalis, 441 

mollis, 441 

viridis, 441 
Sapogenin, 504 
Saponaria, 505 
Saponin, 504 
Saponification, 441 
Sapotoxin, 505 
Sappan, 552 

-wood, 552 
Sappan in, 552 
Sapphire, 146 
Saprine, 511 

Sarcina ventr'iculi in urine, 589 
Sarcolactic acid, 332. 455 
Sarcocephalns esculentus, 475 
Sarkine, 511 
Sarkosine, 510 
Sarracenia purpurea, 540 
f^arsapariUa, 504 
Sarsaparill-saponin, 505 
Sarsa-sa]i()nin, 505 
Sassafras, 470 

cani])hor, 470 

(black) oil, 470 

oil, 470 

swamp. 507 
Sassafrol. 470 
Saturated hydrocarbons. 376 

solutions, boiling points of, 595 
Saturation, 74 

"Saturn." the alchemical name for 
lead. 223 



742 



INDEX. 



Saturnine colic, 223 

Saunders, red, 470, 552 

Savin-oil, 470 

Saxon blue, 554 

Saxony blue, 553 

Scale compounds of iron, 159, et seq. 

Scammonin, 505 

Scammoniolic acid, 505 

Scaminonium, 505 

Scammony, resin of, 480, 505 

Scandium, 683 

Scents, 465 

Scheele's green, 184 

Schist, 146 

Sclicenocanlon officinale, 540 

Schonbein's test for hydrocyanic 

acid, 270 
Schweinfurth green, 184 
Science of chemistry, 18 
Scilla, 505 
Scillain, 505 
Scillin, 505 
Scillipicrin, 505 
Scillitoxin, 505 
Sclerotic acid, 476 
Sclerotinic acid, 476 
Scoparin, 539 
Scopariiis, 539 
Scqpola atropoides, 535 

carniolica, 535 

Japonica, 511, 529 
Scopolamine, 535 

hydrobromide, 535 
Scopoleine, 529 
Scopoletin, 529 
Scott's method for preparing hydro- 

bromic acid, 256 
Scutellaria, 507 
Scyllite, 484 
Sea-salt, 86 

-water, 252, 255, 258 

-weeds, 258 

jelly from, 494 
Sebacate. ethyl, 405 
Secale cereale, 475 
Secondary alcohols, 417 

amines, 508 
Sediments, urinary, 581 

microscopic examination 
of, 583 
Seed-lac, 553 
Seidlitz powder, 306 
Selenium, 683 

Semina cardamomi majoris, 469 
Senega, 505 
Senegin, 505 
Senna, Alexandria, 498 

India, 498 
Sepia, 555 



Sepiadx, 555 
Serpentaria, 527 

Texas, 527 

Virginia, 527 
Serpent's excrement, 583 
Sesame-oil, 444 
Sesamum indicum, 444 
Sesquiterpenes, 415 
Sevum prseparatum, 442 
Shale, 146, 382 
Shark-liver oil. 444 
Shell-fish poison, 511 

-lac, 553 
Sherry wine, 422 
Shot, 222 
Shumac, 343 
Siam benzoin, 459 
Side-chains, 381 
Sidee, 475 
Sienna, 555 

yellow, 551 
Sifting, an aid to analysis, 355, 362 
Silica, 337, 339 
Silicate, aluminium, 104, 146, 337 

calcium, 112, 337 

lithium, 104 

magnesium, 337, 555 
and nickel, 143 

sodium, 337 
Silicates, 337 

quantitative determination of. 
669 

tests for, 339 
Silicic acid, 328, 337, 339 

anhydride, a37, 338 
Silicide, carbon, 339 

magnesium, 339 
Siliciuretted hydrogen, 339 
Silicon, chloride, 339 

derivation of word, 39 

fluoride, 339 

hydride, 339 

oxide, 338 
Silver, 233 

acetate, 284 

ammonium nitrate, test solu- 
tion, 184, 237 

analytical reactions of, 237 

anhydrochromate, 238 

antidotes, 238 

arsenate, 184, 237 

arsenite, 184 

bromide, 237, 257 

chloride, 234, 255 

chromate. 169, 238 

citrate, 310 

coinage, 234 

cyanide, 237, 

derivation of 268 



INDEX. 



743 



Silver, determination of, by cupel- | 
lation, 659 

dichromate, 169 

extraction of, 233 

fulminating, Berthollet's, 236 
ordinary, 237 

German, 132, 143 

iodate, 280 

iodide, 237, 260. 280 

metaphospliate, 333 

monopersulptiate, 296 

nickel, 143 

nitrate, impure, 234 
mitigated, 236 
moulded, 235 
pure, 235 
volumetric solution of, 624 

oxalate, 304 

oxide, 236, 237 

phosphate, 237, 316 

pure, 235 

pyrophosphate, 336 

quantitative determination of, 
658 

sodium thiosulphate, 295 

standard solution of nitrate, 
624 

sulphate, 234 

sulphide, 234, 237, 287 
native, 234 

sulphite, 290 

tartrate, 307 

tree, 238 
Sinalbin, 427 
Sinapis alba, 427 

nigra, 427 
Sinapin acid sulphate, 427 
Sinigrin, 427 
Sinistrin, 505 
Siphon, 116 
Size, 547 
Skullcap, 507 
Slag, blast-furnace, 149 
Slaked lime, 114 
Slate, 146 
Smalt, 141, 553 
Smelting, copper, 205 
Smilacin, 505 
Snake-root, black, 507 
Virginia, 527 
Soap, ammonium, 441 

-bark, 505 

calcium, 441 

Castile, 441 

curd, 441 

for Hindoos, 441 

Mahommedaus, 441 

green, 441 

hard, 441 



Soap, marine, 443 

Marseilles, 441 

mottled, 441 

potassium, 440 

resin, 442 

sodium, 441 

soft, 441 

-stone, 555 

-wort, 505 

yellow, 442 
Socaloin, 413 
Socotrine, aloes, 413 
Soda, 86 

acetate "j 

arsenate 

benzoate 

bicarbonate 

carbonate 

citro- tartrate 

hypophosphite Old names 

nitrate for sodium 

phenolsulpho- salts, which 

nate 

phosphate, 

salicylate 

sulphate 

sulphite 

thiosulphate 

valerate • J 

-ash, 90 

caustic, 86 

-lime, 371 

solution of chlorinated, 91 

washing, 86, 90 

water, 299 
Sodamide, 510 
Sodii acetas, 87 

arsenas, 176 

exsiccatus, 176 

bensoas, 322 

bicarbonas, 87 

hisulphis, 289 

boras, 318 

bromidum, 91 

chloras, 92, 279 

chloriduni, 86 

citras, 92 

hydroxidum, 87 

hypophosphis, 329 

iodlihun, 91 

nitris, 334 

2)he)iolsHl2)honas, 435 

phosphas, 118 

effi'rvescois. 92 
cxsiccafiifi, 92 

pyrophofiphas, 336 

sdlicylas, 457 

sulphas, 253 

sulphis, 289 



744 



INDEX. 



Sodii thiosulphas, 294 
Sodio-feiTous citrate, 161 

hydroxycitrate, 161 
Sodium, 86 

acetate, 87, 281 

test solutiou, 87 
acid carbonate, see Bicarbonate, 

sulphate, 253 
amalgam, 94 

ammouium hydrogen phos- 
phate, 356 
analytical reactions of, 92 
and aluminium, double chlo- 
ride, 146 
and cobalt nitrite, see Cobalti- 

nitrite. 
and platinum chloride, see Chlo- 

roplatinate. 
arsenate, 176 

exsiccated, 176 
arsenite, 174 

benzene- meta-disulphonate, 436 
benzoate, 322, 620 
biborate, 318 
bicarbonate, 87 

chemically pure, 614 

lozenges, 89 

manufacture by the am- 
monia process, 89 
. bisulphite, 289 
bromide, 91, 257 
cacodylate, 323 
carbolate, 457 
carbonate, 86, 89 

chemically pure, 614 

decah yd rated, 90, 91 

manufacture of, 89, 254 

monohydrated, 90 

volumetric determination, 
of, 618 
chlorate, 92, 279 
chloraurate, 198 
chloride, 86 
chloroplatinate, 200 
citrate, 92 
cobaltic nitrite test solution, 

85 
derivation of word, 39 
dihydrogen phosphate, 119 
ethvlate, 423 
flame, 92. 106 
glyoocholate, 550 
gold thiosulphate, 295 
gravimetric determination, 643 
hydrogen carbonate, 87 

sulphate, 252, 253 
hydrosulphide, 287 
hydroxide, 86 

standard solution of, 621 



Sodium hydroxide, volumetric de- 
termination of, 618 
hypochlorite, 91 
hypophosphite, 329 
iodide, 91 
manganate, 139 
meta-bisulphite, 289 
metantimonate, 189 
metantimonite, 189 
metarsenite, 174 
meta-thiantimonite, 189 
methyl arsenate, 323 
nitrate, 86, 271 

crude, 258 
nitrite, 334 
occurrence, 86 
oleate, 439 

ortho-thiantimonite, 190 
oxalate, 303 
permanganate, 139 
peroxide, 23, 92 
persulphate, 296 
phenol, 457 
phenolsulphouate, 434 
phenyl carbonate, 457 
phosphate, 91. 118 

effervescent, 92 

how prepared from calcium 
phosphate, 118 

test solution, 119 
potassium, lithium, and am- 
monium, separation of, 
106, 107 

tartrate, 79, 305, 306 
preparation of. 86 
pyroavseuate, 176 
pyroborate, 318 
pyrophosphate, 336 
quantitative determination of, 

644 
salicylaldehyde, 458 
salicylate, 457 

salts, analogy of, to potassium 
salts, 92 

sources of, 86 
silicate, 339 

silver thiosulphate, 295 
stannate, 195 
sulphate, 253, 291 
sulphide, 287 
sulphite, 289 
taurocholate, 550 
tetraborate, 318 
tetrathionate, 295 
thiantimonate, 189 
thiosulphate, 294 
urate, 346 
valerate, 346 
zincate, 137 



INDEX. 



745 



Soft soap, 441 
S.)ils, analysis of, 681 
Sjlauidine, 538 
Sjlauine, 538, 541 
Solanum dulcamara, 538 
tuberosum, 538 

starch of, 490 (fig.) 
Solazzi juice, 500 
Solder, 193, 222, 228 
Solid caustic potash, 72 

fats, 442 
Solids, to take the specific gravity 
of, 601, et seq. 
lighter than water, to take the 

specific gravity of, 604 
soluble in water, to take the 
specific gravity of, 603 
Solubility of carbonic anhydride in 
water, 298 
of gases in water, 23 
or insolubility of salts in water, 
table of, 351 
Soluble cream of tartar, 319 
ferments, 421 
glass, 339 
saccharin, 429 
starch, 492 
Solution of ammonia, 95 
ammonium acetate, 95 
citrate, 98 
sulphide, 100 
arsenic, acid, 174 
alkaline, 174 
calcium chloride, 112 

sulphate, 122 
caustic potash, 72 
chlorine compound, 254 
De Valangin's, 174. 
Donovan's, 173 
ferric chloride, 156 
nitrate, 162 
sulphate, 157, 159 
ferrous sulphate, 151 
Fowler's. 174 
formaldehyde, 448 
fractional, 90, 362 
hydrogen sulphide, 101 
iodine, 259- 
lead subacetate, 223 
lime, 114 
litmus, 99, 620 

magnesium ammonium sul- 
phate, 667 
citrate, 126 
nitroglycerin, 438 
normal chromate, 167 
phosphoric acid, 313 
potash, 72 
])()tassinm permanganate, 139 



Solution of sodium arsenate, 176 

of solids, 357-361 

theory of, 363 

zinc chloride, 134 
Sonnenschein's process for poison- 
ous alkaloids, 569 
Soot, 36, 297 
Sophora tomentosa, 534 
Sophorine, 534 
Sorbinose, 483 
Sorbite, 445 
Sorrel, salt of, 303 

wood-, 303 
Soymida fehrifuga, 507 
Soymidse corlex, 507 
Sozoiodol, 429 
Sozolic acid, 429 
Spanish licorice, 500 
Spar, fluor, 112, 327 

heavy, 109, 290 
Sparteine, 539 
Sparteinse sulphas, 539 
Spathic iron -ore, 149 
Spearmint-oil, 469 
Specific gravities, 47 
Specific gravity, 599, et seq 
bottles, 599 
of gases, 48, 604 
of liquids, 47, 599 
of official liquids, 600 
of oxygen, 29 
of powders, 603 
of solids, 47, 601, et seq. 

lighter than water, 604 
of soluble substances, 603 

heat, relation to atomic weight, 
58 
Spectroscope, 250, 559 
Spectrum, 559 

analysis, 250, 559 
Specular iron-ore, 149 
Speculum metal, 193 
Speiss, 143 
Spermaceti, 426 
Spermatozoa in urine, 589 
Sperm-oil, 426 
Sphacelinic acid, 476 
Spinelle, 146 
f^pinra nlmaria, 458. 503 
Spirit, methylated, 415 

of cami)hor, 473 

of French wine, 422 

of myrcia, 422 

of nitrous ether, 401 

of turpentine. 415 

petroleum, 406 

proof, 423 

pyroxylic, 418 

rectified, 131 



746 



INDEX. 



Spirit, wood-, 418 
Spirits, 422, 592 
Spiritas xtheris, 432 

compositiis, 432 
nitrosi, 334, 402 
ammonix, 95 

aromaticus, 97 

volumeti-ic determin- 
ation of, 617 
amygdalse amarse, 465 
anisi, 465 
camphorse, 473 
^mnamomi, 465 
frumenti, 422 
gaultherise, 465 
glycerylis nitratis, 438 
juniperi, 465 
lavandidse, 465 
menthse piperitse, 465 

viridis, 465 
?iiiri didcis, 403 
ri)ii gallici, 422 
Spodumene, 103 
Spogel seeds, 495 
Sponge, 258, 546 
Spongine, 546 
Spongy platinum, 201 
Spontaneous ignition, 163 
Spotted cranesbill, 343 
Spruce fir, 476 
Spurge laurel, 476 
Squahis carcharias, 444 
Squill, 495 
-bulb, 505 
vinegar of, 282 
Standard pressure, 47 
Standard solution of iodine, 628 

potassium dichromate, 631 

permanganate, 633 
silver nitrate, 624 
sodium hydroxide, 621 

thiosulphate, 635 
sulphuric acid, 614 
temperature, 47 
Stannate, sodium, 195 
Stannates, 194 
Stannic acid, 194, 196 
anhydride, 194 
chloride, 194 
oxide, 193, 194 
sulphide, 196 

anhydrous, 196 
Stannous chloride, 194 
solid, 194 
test solution, 194 
hydroxide, 196 
oxide, 196 
sulphide, 195 
Stannum, 39 



Staphisagria, 534 
Star-anise oil, 466 
Starch, 487, 555 

action of diastase upon, 490, 492 
of dilute acids upon, 493 

animal, 491 

barlev, 488 

blue, 487 

bromide, 258 

cellulose, 489 

granules, composition of, 487, 
489 

iodide, 80, 260, 488 

maize, 487 

mucilage of, 488 

potato, 487 

quantitative determination of, 
677 

rice, 488 

soluble, 493 

wheat, 488 

white, 494 
Starches, microscopy of, 489 
Stas's process for poisonous alka- 
loids, 568 
State of concentration, 251 
Stavesacre, 534 

seeds, 534 
Steapsin, 549 
Stearic acid, 437, 439, 453 
Stearine, 439 
Stearoptens, 464 
Steatite, 555 
Steatolvtic enzvme, 549 
Steel, 150 

wine, 161 
Stereochemical theory, 481 
Stibines, 509 
Stibium, 37, 186 
Stibnite, 186 
Slick lac, 553 

licorice, 500 
Still, 130 
StiUingia, 539 

sylvatica, 539 
Stillingine, 539 
Stone-coal. 193 

red, 552 

ware, 338 
Storax, 323, 461, 474 
Stout, 422 
Stranionixim, 535 
Strasburg turpentine, 415 
Strawberry, sugar in, 482 
Stream-tin, 193 
"Strength " of acids, 251 
Strontianite, 111 
Strontii bromidum, 111 

iodidum. 111 






INDEX. 



747 



Strontii salicylas, 111 
Strontium, 111 

analytical reactions of, 111 

carbonate, 111 

chromate, 112 

derivation of word, 39 

flame, 112 

liydroxide, 111 

nitrate, 111 

salicylate, 111 

sulphate, 111 

sulphide. 111 
Strophanthidin, 506 
Strophanthin, 506 
Strophanthinum, 506 
Strophanthiis, 506 

Kombe, 506 
Structure of flame, 28 

of molecules, 374, et seq. 

of organic compounds, 374 
Structural formulae, 375 
Strychnina, 524 
Stryclminse nitras, 524 

sulphas, 524 
Strychnine or strychnia, 523, 541 

analytical reactions of, 524 

citrate, 524 

hydrochloride, 524 

in organic mixtures, detection 
of, 565 

nitrate, 524 

physiological test, 525 

sulphate, 524 
Strychnos Ignatius, 523 

nux vomica, 502, 523 
Styracin, 460 
Styrax, 461, 474 
Styrol, 460 
Styrone, 460 
Subacetate, copper, see Oxyacetate. 

lead, 223 
Subcarbonate, iron, 153 

bismuth, 230 
Subchloride, mercuiy, see Mercu- 

rous chloride. 
Suberate, ethyl, 405 
Sublimate, 96 

corrosive, 213 
Sublimation, 96, 214 
Sublimed sulphur, 284 
Subnitrate, bismutli, 228 
Substances readily oxidized, quanti- 
tative determination of , 628 

reduced, quantitative determi- 
nation of, 634 
Substitution, 179, 395, 410 

products, 395 
Succinate, ammonium, 332 

barium, 340 



Succinate, ferric, 340 

potassium hydrogen, 340 
Succinates, 339 
Succinic acid, 339, 461 
Succinum, 339 
Succus limonis, 310 
Sucrate, iron, 152 
Sucrose, 420, 484 
Suet, 442 

prepared, 442 
Suffioni, 318 

Sugar, action of alkali upon, 485 
amount in various fruits, 482 
barley, 485 
beet root, 481, 484 
brown, 484 
burnt, 485 
candy, 484 
-cane, 482, 484 
cube, 484 

detection of, in urine, 576 
from caoutchouc, 484 
eucalyptus, 486 
fish, 484 
larch, 486 
milk, 483 
mountain ash, 483 
muscles, 483 
starch, 483 
Turkish manna, 486 
fruit, 482 
grape-, 482 
inverted, 482 
lichen, 445 
loaf, 484 
lump, 484 
-maple, 484 
milk-, 486 
moist, 484 
of gelatin, 550 
of lead, 223 
patent, 483 
quantitative determination of, 

676 
test for, 482 
-sand, 486 
sj^rup, 484 
Suint, 440 

Sulphamido-benzoatcs, 429 
Sulphanilic acid, 335 
Sulphate, acid potassium, 272, 291 
sodium, 253 
aluminium, 147 
ammonium, 94 
ferrous, 152 
ferric, 147 
barium. 109. 290, 293 
boborino, 529 
bismuth, 229 



•48 



INDEX. 



Sulphate, calcium, 112, 122, 290 
cliromic, 166, 168 
cinchouidiue, 521 
cobalt, 142 
codeine, 516 
copper, 206 

anhydrous, 206 
cupric, 206 

ammonium, 207 
ethyl hydrogen, 392 
ferrous, 151 

solution of, 152 
hydrogen, 293 
indigo, 276 
iron (ferric) and ammonium, 

147 
iron (ferrous) and ammonium, 

152 
lead, 226 

magnesium, 123, 290 
manganese, 138, 254 
mercuric, 212, 213 
mercurous, 212, 213 
morphine, 514 
nickel, 143 
potassium, 78, 272 

hydrogen, 272 
quinine, 519 
silver, 234 
sodium, 254, 291 

hydrogen, 252 
strontium. 111 
strychnine, 523 
zinc, 133 
Sulphates, 290, et seq. 

analytical reactions of, 293 
quantitative determination of, 
664 
Sulphations, 363 
Sulphide, allyl propyl, 427 
antimony, 186, 189, 190 
arsenic, 173, 183 

native, 173 
barium, 109 
bismuth, 227, 230 
cadmium, 232, 233 
calcium, 120 
cobalt. 142 
copper, 206 

and iron, 205 
cupric, 206, 287 
hydrogen, 100, 164, 287 
iron, 37, 154. 164, 165 
lead, 222, 225 

native, 222 
manganese, 140 
mercury, 219 

native, 209 
molybdenum, 316 



Sulphide, nickel, 143 

platinum, 200 

potassium, 73, 287 

silver, 233, 237, 287 
native, 233 

sodium, 287 

stronium, 111 

tin, 195, 196 

zinc, 131, 136 
native, 131 
Sulphides, 284 

analytical reactions of, 287 

detection of, in presence of sul- 
phites and sulphates, 290 

quantitative determination of, 
663 
Sulphite, barium, 291 

calcium, 290 

silver, 290 

sodium, 289 

zinc, 136 
Sulphites, 288 

acid, of organic radicals, 428 

analytical reactions of, 289 

detection of, in presence of sul- 
phides and sulphates, 290 

quantitative determination of, 
664 
Sulphocarbolates, 434 
Sulphocarbolic acid, 434 
Sulphocarbonates, 302 
Sulphocarbonic anhydride, 302 
Sulphocyanates, see Thiocyanates. 
Sulphocyanides, see Thiocyanates. 
Sulphonal, 428 
Sulphonic acids, 428 
Sulphonethylmethane, 428 
Sidphonethylmethanum, 428 
Sulphonmethane, 428 
SaJph on meth a n n m , 428 
Sulphostannates. see Thiostannates. 
Sulphovinic acid, 293, 392 
Sulphur, 36, 284 

adulteration of, 286 

alcohols, 428 

allotropic forms of, 285 

amorphous, 285 

arsenic sulphide in, 183, 285 

black, 285 

bromide, 287 

calcareous precipitated, 286 

chloride, 286 

derivation of word, 39 

determination of, 663 

ethers, 432 

flowers of, 284 

hvpochloride, 2S7 

iodide, 259, 287 

liver of, 73 



INDEX. 



749 



Sulphur, milk of, 285 

molecular formula of, 285 
octahedral, 285 
oxyacids, 296 
plastic, 285 
precipitated, 285 
prismatic, 285 
roll, 284 
sublimed, 284 
washed, 285 
Sulphur lotum, 285 
prsecipitatHin, 285 
sublimatum, 284 
vivum nigrum, 285 
Sulphurated antimony, 189 
lime, 120 
potash, 73 
Sulphurets, see Sulphides. 
Sulphuretted hydrogen, see Hydro- 
gen sulphide. 
Sulphuric acid, 290, et. seq. 
antidotes to, 294 
aromatic, 293 

determination of, in vine- 
gar, 664 
diluted, 293 
fuming, 293 
impurities in, 292 
manufacture of, 291 
nitrous acid in, 334 
Nordhausen, 293 
organic mixtures, detec- 
tion of, in, 563 
purlflcation of, 292 
standard solution of, 614 
volumetric determination 
of, 623 
anhydride, 292, 293 
Stilphiiris iodidum, 259, 287 
Sulphurous acid, 288 

volumetric determination 
of, 628 
anhydride, 36, 213, 288 
Sulphydrate ammonium, solution 
of, see Ammonium hydrosul- 
phide. 
Sulphydric acid, 284 
Sumac or sumach, 343 
Sumatra benzoin, 321 

camphor, 472 
Sumbul, 478 
radix, 478 
root, 478 
Sumbulic acid, 478 
Sumbuolic acid, 478 
Supori)h<)spiiate, 315 
Sui)i)ortcrs of combustion, 28 
Suppositories, 592 
Surface, unit of, 41 



Surgery, 18 

Swamp sassafras, 507 

Sweet birch, oil of, 458, 466 

flag, oil, 470 

spirit of nitre, 403 
Sweetbread, 549 
Swertia chirayita, 335 
Sylvestrene, 415 
Sylvic acid, 441, 474 
Symbol, function of a, 58 
Symbol, atomic, 69 

of elements, 59, 682 

illustration of chemical action 
by means of, 59, et. seq. 
Symmetrical compounds, 410 
Sympathetic inks, 143 
Synaptase, 497 
Synthesis, 50 
Syrup, golden, 485 
Syrups, 592 

specific gravities of, 601 
Syrnpus, 484 

acidi citrici, 309 
hydriodici, 260 

aurantii florum, 467 

calcii lactophosphatis, 331 

calcis, 114 

ferri iodidi, 37, 155 

hypophospJiitum, 329 
compositns, 330 

tolutamis, 460 

Tables, various, see Appendix, 

Tacks, tin, 193 

Talc, 146, 555 

Talcum, 555 

Tallow, 442 

Tamarindus, 308 

Tampico jalap, 502 

Tannate. antimony, 342 

ferric, 165, 341 

gelatin, 341 
Tannic acid, or tannin, 340, 459 

test solution, 341 
Tanning, 341 
Tantalum, 683 
Tapioca, 488 

starch, 488, 490 (fig.) 
Tar, 416, 478 
Taraxacin, 507 
Taraxacum, 507 
Tartar, cream of, 71, 84, 305 

emetic, 188 

determiuation of antimony 
in. 630, (552 

meaning t>f. 305 

soluble croani of. 319 
Tartarated nntiuiouy, 188 
Tartaric acid, 305 



INDEX. 



Taiiiaric acid test solution, 306 

volumetric determinatiou 
of, 623 
series of acids, 462 
Tartarus boraxatus, 319 
Tartrantimouious acid, 188 
Tartrate, acid ammonium, 102 
potassium, 78, 83, 305 
antimonyand potassium, 160, 188 
calcium, "^305, 307 
ferrous, 161 
iron, 161 

and ammonium, 161, 308 
potassium, 159, 161, 308 
morphine, 514 
potassium, 78. 305 
acid, 78, 83, 305 
and sodium, 79, 305, 306 
antimonyl, 188 
silver, 307 
Tartrates, 305 

analytical reactions of, 307 
volumetric determination of, 
619 
Tartronic acid, 463 
Taurine, 510, 550 
Taurocholates, 550 
Taxine, 539 
Tea, 539 
Tea-oil, 444 
Telini fly, 473 
Tellurium, 683 
Temperature, absolute, 46 

correction of volume of gas for, 

46, 605 
measurement of, 43, 593 
standard, 47 
Temporary hardness in water, 301 
Terebenthene, 415 
Terebene, 416 
Terebenum, 416 
Terebinthina, 415 

canadensis, 415, 478 
Terephthalic acid, 462 
Terminalia chebula, 340 
Terpene series of hydrocarbons, 415 
Terpeneless oils, 465 
Terpenes, 415 
Terpin hydrate, 416 
Terpinene, 415 
Terpineol, 467 
Terpini hydras, 416 
Terpinol, 416 
Terpin olene, 415 
Terra di sienna, 552 

Japonica, 342 
Tertiary, alcohols, 417 
amines, 508 
amyl alcohol, 425 



Test-papers, 99 

-tube, 20 
Tests, 83 

chemistry of, 83 
Tetano-cannabin, 475 
Tetanine, 511 
Tetrabasic acids, 463 
Tetraborate, sodium, 318 
Tetrachloride, carbon, 396 
Tetrachloromethane, 396 
Tetra-iodo-pyrrol, 511 
Tetrahydric alcohols, 445 
Tetramethylthiouine hj'drochlo- 

ride, 556 
Tetrathionate, sodium, 295 
Tetrathionic acid, 296 
Tetrethyl-ammonium iodide, 508 
Tetronal, 428 
Texas serpentaria, 527 
Tfol, 338 

Thalleioquin, 519 
Thalline, 523 
Thallium, 683 
Thebaine, 517, 541 
Theine, see Caffeine. 
Thenard's-blue, 553 
Theobroma-cacao. 442, 539 

-oil, 442 
Theobromine, 539 

relation of to caffeine, 539 
Theophylline, 539 
Theory of solution, 363 
Therapeutics, definition and deriva- 
tion of, 18 
Thermometers, 43, 593 

Centigrade, 44 

Fahrenheit, 44 
Thermometric scales, conversion of 

degrees of, 44 
Thiantimonate, sodium, 189 
Thio-alcohols, 428 
Thio-antimony compounds, 189,190 
Thio-arsenic compounds, 183 
Thiocarbonates, 302 
Thiocarbonic anhydride, 302 
Thiocyanatc, ammonium, 269 

ferric, 165, 269, 344 

mercuric, 345 

potassium, 344 
Thiocyanates, 344 

distinction of, from acetates 
and meconates, 332, 344, 345 
Thiocyanic acid, 344 
Thiocyanogen, 345 
Thio-ethers, 432 
, Thionic acids, 297 
Thiostannates, 196 
Thiosulphate, calcium, 286 

sodium, 289, 294 



INDEX. 



7ol 



. • ..-ulpbate, sodium gold, 295 
V) reparation of, 294 

iver, 295 
standard solution of, 635 
Tl' .aulphates, 294 

tests for, 295 
i hiosulphuric acid, 294 
Thio-tiu compounds, 196 
Thorium, 683 
Thorn-apple, 535 
Thoroughwort, 507 
Thrombosin, 544 
Thujone, 470 
Thusmasculmn, 479 
Thyme, 470 

oil of, 470 
Thymene, 470 
Thymol, 466, 470 

iodide, 471 
Thymolis iodidum, 471 
Thymus vulgaris, 470 
Tiglic acid, 444 
Tiles, 338 
Tin, 193, 683 

amalgam, 193 

analytical reactions of, 195 

and antimony, separation of, 
197 

antidotes to, 197 

arsenic and antimony, analyti- 
cal separation, of, 202, et seq. 

block, 193 

chlorides, 194 

derivation of word, 39 

dropped, or grain, 193 

foil, 193 

granulated, 193 

oxides, 194 

perchloride, see Stannic chlo- 
ride. 

plate, 193 

powdered, 193 

prepare-liquor, 195 

-stone, 193 

tacks, 193 

-white cobalt, 141 
Tincal, 318 
Tinctura cautharidis, 473 

ferri chloridi, 156 

hydrastis, 530 

iodi, 259 

physostigmatis, 537 

strophanthi, 506 
Tincture of phenol-pthalcin, 624 
Tinctures, 592 
Tinospora cordifolia, 507 
Tinosporie radix et caales, 507 
Titanium, 683 
Tobacco. 536 



Toddalia, 507 

aciileata, 507 
Toddaliie radix, 507 
Tolene, 460 
Tolu, balsam, 323, 460 

syrup, 460 
Toluene, 406, 408 

-sulphonic acid, 428, 429 
amide, 429, 
chloride, 429 
Toluidine, 408 
Toluol, 408 
Tolyl alcohol, 435 
Tonka bean, 461 
Tourmalines, 337 
Toxicodendric acid, 343 
Toxicology, 559 
Tragacanth, 121, 494 
TragacantKa, 121 
Tragauthin, 494 
Treacle, 285 
Tree, lead, 227 

silver, 238 
Tri-acid bases, 66 
Triamines, 509 
Triangle, wire, 103 
Triatomic alcohols, 437 
Tribasic acids, 66, 251, 462 
Tribromomethane, 400 
Tribromophenol, 434 
Tricarballylic acid, 462 
Trichloracetal, 450 
Trichloracetic acid, 451 
Trichloraldehyde, 449 
Trichlorbutylidene glycol, 453 ^ 
Trichlorethylidene ethyl ether, 13;.' 

glycol, 450 
Trichlorobeuzene, 410 
Trichloromethane, 396 
Trichloromethylbenzene, 322 
Trichloro-tertiary-butyl alcohol. 

424 
Trichlorotoluene, 322, 409 
Triethylamine, 508 
TriethjM -ammonia, 508 

ammonium- iodi do, 508 
Trigonella fcvnum-qra'cnm, 540 
Trigonelline, 540 " 
Trihydric alcohols, 437 
Trihydroxybenzene, 445 
Trihydroxy-benzoic acid. 459 
Trihydroxyl derivatives of hyc 

carbons, 437 
Tri-iodomctl\ano, 401 
Trimethyl beiizono, 406 

methane, 386 
Trimethylamine, 508 
Trimothylxanthine, 539 
Trini trine, 438 ~* 



752 



INDEX. 



Trinitrocellulin, 495 
Triuitio-phenol, 435 

tertiary-butyl-toluene, 547 
Trioual, 428 
T.'ioses, 481 
T. iphane, 103 
T i pie phosphate, 584 
f poll powder, 337 
U ithiouic acid, 296 
'J'riiicum, 507 

repens, 507 

starch, fig. of, 490 
T;i valence, 63 
"^ . valent radicals, 63 
7 rochisci acidi tannici, 341 

potassii chloratis, 278 

sodii bicarbonatis, 89 
i'vopate, tropiue, 528 
'ivijpeines, 528 
Piopic acid, 528 
Tropidine, 528 
" • pine, 528 

esters, 528 

•psin, 549 
. )es for collecting gases, 21, 22, 
23 

funnel, 25 

glass, see Glass tubes. 
T igsten, 683 
1 .licin, 496 
T. rbad, 502 
l^ii-bid, 502 
Turmeric, 471, 551 

oil, 471 

paper, 99 
Tiiiaerol, 471 

jurnbuH's blue, 164, 327, 554 
Turnsole, 554 
Turpentine, 415 

American, 415 

Bordeaux, 415 

Canadian, 415 

Chian, 415 

crude, 415 

French, 415 

rectified oil of, 4l5 

Russian, 416 

spirit of, 415 

Strasburg. 415 

Venice, 415 
Turpentines, 478 
Turpeth mineral, 213 

vegetable, 213, 502 
Turpethin, 502 
Tepethum, 502 
Turps, 415 

T'l'ophora asthmatica, 535 
''vlopliorine, 535 
. ",vpe-mt't;il, 186, 222,228 



Tyrosine, 510, 583 
Tyrotoxicon, 511, 571 

Ulexine, 534 
Ultimate analysis, 670 
Ultramarine blue, 554 

green, 554 
Ultraquinine, 523 
Umbelliferone, 479 
Umber, 555 

Ungiientum acidi tannici, 341 
belladonnx, 529 
hydrargyri, 210, 440 
ammoniati, 218 
dilutum, 210 
nitratis, 212 
oxidi flavi, 216 
rubri, 216 
iodi, 259 
paraffini, 388 
veratrinse, 540 
zinci oxidi, 135 
Units of length, surface, capacity, 

and mass, 40, 41 
Univalence, 63 
Univalent radicals, 63 
Unsaturated compounds, 389 
Unsymmetrical compounds, 410 
Uranium, 683 
Urari, 525 
Urate, lithium, 104 
Urates, 345 

Urcoola olasiie.a, 471 
Urea, 324, 455, 510, 573 
artificial, 324, 573 
determination of, in urine, 578 

et seq. 
nitrate, 574 

test for excess of, in urine, 578 
tests for, 573 
Ureometer, Doremus, 579 
Urethane, 455 

Uric acid, 345, 539, 577, 581, 584, 
589-591 
rough determination of, in 
urine, 578 
Urinary calculi, 572 

examination of, 589 
sediments, 581 

microscopical examination 
of, 583 
Urine, 345, 572 

average composition of solids, 

572^ 573 
color of, 581 
diabetic, 577 
determination of sugar in, 678 

of urea in, 578 
morbid, examination of, 575 



INDEX, 



753 



Urine, proteids iu, 575 
Uriuometer, 577, 601 
Urobilin, 574 
Urochrome, 574 
Uroerythrin, 574, 582 
Urostealitb, 589 
Uvpe tirsi, 342 



Valency, 62 

variatiou iu, 150, 151,327 
Valerate, aruyl, 347, 405 

cupric, 348 

ferric, 347 

sodium, 346 

zinc, 136, 347 
Valerates, 346 
Valerian oil, 471 
Valeriana, All 

officinalis, 471 

WalHchii, 471 
Valeric, or valerianic acid, 346, 425, 

453 
Valerone, 464 
Valonia, 341 
Vanadates, 318 
Vanadinite, 318 
Vanadium, 317, 683 

relationship to nitrogen, phos- 
phorus, and arsenic, 317 
Vanilla, 459 

planifolia, 459 
Vanillin, 459 
VaniUiiinm, 459 
Vapor-density. 48. 605 

determination, Dumas' 
method, 606 
Gay Lussac's method, 

606 
Meyer's method, 606 
Variolaria, 554 
Vasaka, 540 
Vaseline, 388 
Vasicine, 540 
Vegetable albumin, 546 

alkaloids, 510 

and animal life, relation of oxy- 
gen to. 24 

casein, 546 

crocus, 551 

fibrin, 545 

gelatin, 494 

green, 554 

jellv, 494 

oil, 439 

rouge, 553 
Vegeto-animal alkaloids, 511 
Venetian rod, 158 
Venice turpentine, 415 

48 



" Venus, " the alchemical name for 

copper, 205 
Veratralbine, 536 
Veratridine, 540 
Veratrina, 540 
Veratrine, or Veratria, 536, 540, 541 

oleate of, 440 
Veratroidine, 536 
Veratrnm, 526 

album, 536 

officinale, 540 

viride, 536 
Verbena oil, 471 
Verdigris, 206 
Verjuice, 305 
Vermillion, 219, 552 
Vermouth, 422 
Veronica virginica, 307 
Viburnin, 507 
Viburnum opulus, 507 

prunifolinm, 507 
Vinegar, 281 

brewed, 282 

brown, 281 

determinatio] ■ of mineral acids 
in, 664 

malt, 282 

of opium, 282 

of squill, 282 

red-wine, 281 

white, 281 

white-wine, 281 

wood, 281 
Vinum antimonii, 189 

ferri, 161 

amarum, 161 

ipecacuanhx, 535 
Violet, 458 

Virginia snakeroot, 527 
Vitellins, 543 
Vitriol, blue, 152. 206 

green, 152, 292 

oil of, 292 

white. 133 
Volatile oils, 464 

concentrated. 465 
Volatility of ammonium salts, 103 
Volatilization. 103 
Volcanic an\nionia. 94 
Volume, combination by. 60 

of gas. corrections of, 47. 604. 
605 
Volumetric doterniination of: — 
acetic acid. (>22 
annnonia. solulitmsof, 615 
anuuoniuni bromide, 626 

carbonate, (517 
antimony. 630 
arsenic, 629 



754 



INDEX. 



Volumetric determination of :— 
borax, 617 

chlorine, solution of, 635 
citric acid, 623 
ferric salts, 637 

ferrous carbonate, saccharated, 
632 

iodide, 627 

sulphate, 632 
hydrochloric acid, 623 
hy^; '■-- acid, 625 

iodine, 63b 
iron iodide, 627 

magnetic oxide, 633 

saccharated carbonate, 632 

.sul])hate. 632 
lactic acid, 623 
load Hceiatt, 657 

sub-actt;ite, solution of, 657 
lin^e, r^i'Mrl'iated, 636 
'.liifion of, 636 

^^r.' '-■, ol7 

water, 617 
nitric ?.cid, 623 
oxalic acid, 634 
oxalates, 634 
potassium bicarbonate, 618 

bromide, 626 

carbonate, 618 

citrate, 619 

cyanide. 626 

hydroxide, 618 

iodide, 6-^7 

tartrate, 619 
Eochelle salt, 620 
saccharated ferrous carbonate, 632 
soda, chlorinated, solution of, 

636 
sodium, 618 

arsenate, 629 

benzoate, 620 

bicarbonate, 618 

carbonate, 618 

citrate, 619 

hj-droxide, 613 

iodide, 627 

tartrate, 619 

tbiosulphate, 632 
spiritus ammonix aromaticus, 617 
sulphuric acid, 623, 628 
sulphurous acid, 628 
tartaric acid, 623 
Volumetric quantitative analysis, 

611 
solutions, 614, 621, 624, 62S. 6:51. 

633, 635 
Vouacapoua araroba, 412 
Vulcanite, 471 
Vulcanized India-rubber, 471 



Wahoo bark, 507 

Wakhma, 527 

Warmth of animals, how kept up, 24 

Wash -bottle, 116 

hot- water, 116 
Washing precipitates, 116 

-soda, 86, 90 
Water, 26, 27, 129, see Aqua. 

aerated, 299 

ammonia, 94 

in potable, 616 

baryta, 109 

-bath, 115, 118 

bitter almond, 268 

boiling-point of, 594, 595 

chalybeate, 149 

chlorine, 34, 254 

chloroform, 400 

composition of, 27 

creosote, 434 

cubic inches of, in a gallon, 606 

deteimination of, 669 

distilled, 131 

formation of, 27 

-glass, 338 

Goulard, 224 

hardness of, 301 

-hemlock, oil of, 468 

lead in, 225 

lime, 114 

maximum density point of, 47 

nitrates in, 334 

of crystallization, 90 

quantitative determination 
of, 669 

-oyen, 640 

oxygenated. 109 

potash, 299 

purification of, 129, 130 

soda, 299 

weight of a cubic inch of, 606 
Wax, bees, 426, 

Carnauba. 426, 453 

paraffin, 387, 388 
Waxes, 426 
Wedgwood- ware. 338 
Wei shing- tubes, 639 
Weight, 598 

molecular, 53, et seq. 

of air, 605 

of hydrogen. 606 

of water, 606 
Weights, 598 

and measures, 40, et seq. 

and measures of the metric sys- 
tem, 40, 43 

atomic, 52, 55 

molecular, 54 
Weld, 552 



INDEX. 



755 



Welding, 150 
Wbeaten flour, 488 
Wheat-starch, 488, 490 (fig.). 
Whey, 486, 544 
Whisky. 422 
White acid, 328 

arsenic, 173, 174 

Castile soap, 441 

hellebore, 536 

American, 536 

indigo, 553 

lead, 223, 555, 657 

marble, 112 

mustard, 427 

pepper, 538 

petrolatum, 388 

pigments, 555 

poppy, 513 

precipitate, 218, 255 
fusible, 218 
infusible, 218 

resin, 474 

vitriol, 133 

wax, 426 
Whiting, 117, 555 
Whortleberry, sugar in, 482 
Wild black cherry, 498 

indigo, 529 
Willow-bark, 503 
Wine, 422 

antimonial, 189 

apple, 422 

heavy oil of. 432 

ipecacuanha, 534 

iron, 161 

bitter, 161 

oil of, 432 

orange, 422 

pear, 422 

quinine, 519 

sherry, 422 

steel, 161 

vinegar, 281 
Wines, 422, 592 
Winter-green, oil of, 458 
Wire-gauze, 35 

triangle, 103 
Witch-hazel, 507 
Witherite, 109 
Wood, charcoal, 298 

creosote, 434 

-naphtha, 419 

sorrel, 302 

specific gravity of, 604 

-oil, 477 

-spirit, 418 

-tar, 416, 478 

vinegar, 281 
Woody night-sliadc, 538 



Wool fat, 440 

hydrous, 440 
Woorara, 525 
Wormseed, 471 

American 471 

oil, 471 
Wormwood, 340, 498 
Wourali, 525 
Writing-ink, 341 
Wrought iron, 150 

Xanthine, 539 

calculus, 589, 591 
Xanthocreatinine, 510 
Xanthorrhiza apiifolia, 530 
Xayithoxylon fraxineum, 530 
Xenon, ,32, 33 
Xylene, 406 
Xylenes, 436 
Xyloidin, 488 
Xylonite, 496 

Yeast, 420 
Yelk of egg, 543 
Yellow, chrome, 226, 551 

cinchona bark, 519 

coloring matters, 551 

dock, 412 

jasmine, 535 

mercuric iodide, 211 
oxide, 216 

ochre, 551 

parilla, 530 

prussiate of potash, 266, 326 

sienna, 551 

soap, 442 

wax, 426 

wood, 551 
Yolk of egg, 543 
Ytterbium, 683 
Yttrium, 683 

Zaffre, 141 
Zea Mays^, 487 
Zinc, 131 

acetate, 135 

analytical reactions of, 136 

antidotes to, 137 

arsenate, 185 

In-omido, 134 

carbonate, 131, 134, 137 

chloride, 133 

derivation of word, 39 

detection of. in presence of man- 
ganese, nickel, and cobalt, 
145 

ferrocvanide. 137 

granubted, 25 

hvdroxido, 137 



'56 



INDEX. 






Zinc, hydroxycarbonate,134,135,137 

in organic mixtures, detection 
of, 561 

iodide, 134 

methide, 385 

molecular formula of, 132 

oleate, 440 

oxide, 134 

plienolsulphonate, 136, 435 

quantitative determination of, 
648 

stearate, 136 

sulphate, 132 

sulphide, 136 
native, 131 

i>;. ohite, 136 

\h: ..te, 136, 347 

wiiiLc. 134, 555 
Zincate, potassium, 137 



' Zincate, sodium, 137 ^ 

Zinci acetas, 135 

carbonas prxcipitatus, 134 

chloridi liquor. 134 

chloridnm, 133 

oxid'i nnguetdnm, 135 

oxidum, 135 

phenohidphonas, 136, 435 

steams, 136 

sulphas, 132 

valeras, 136, 347 
Zincum, 132 
Zingiber, 471 
Zirconium, 683 
Zymase, 420 
Zymolysis, 421 
Zymosis, 421 
Zymotic alkaloids, 511 



'2X3^ 



